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101 102<link rel="https://api.w.org/" href="https://eequalspi.com/index.php/wp-json/" /><link rel="EditURI" type="application/rsd+xml" title="RSD" href="https://eequalspi.com/xmlrpc.php?rsd" /> 103<meta name="generator" content="WordPress 7.0.7" /> 104<style>.recentcomments a{display:inline !important;padding:0 !important;margin:0 !important;}</style><style>img.zoooom,.zoooom img{padding:0!important;}</style><link rel="icon" href="https://eequalspi.com/wp-content/uploads/2017/02/cropped-eequalspi_header-32x32.png" sizes="32x32" /> 105<link rel="icon" href="https://eequalspi.com/wp-content/uploads/2017/02/cropped-eequalspi_header-192x192.png" sizes="192x192" /> 106<link rel="apple-touch-icon" href="https://eequalspi.com/wp-content/uploads/2017/02/cropped-eequalspi_header-180x180.png" /> 107<meta name="msapplication-TileImage" content="https://eequalspi.com/wp-content/uploads/2017/02/cropped-eequalspi_header-270x270.png" /> 108<link rel='stylesheet' id='mediaelement-css' href='https://eequalspi.com/wp-includes/js/mediaelement/mediaelementplayer-legacy.min.css?ver=4.2.17' media='all' /> 109<link rel='stylesheet' id='wp-mediaelement-css' href='https://eequalspi.com/wp-includes/js/mediaelement/wp-mediaelement.min.css?ver=7.0.7' media='all' /> 110 111</head> 112 113<body class="home blog wp-embed-responsive wp-theme-twentysixteen hfeed"> 114<div id="page" class="site"> 115 <div class="site-inner"> 116 <a class="skip-link screen-reader-text" href="#content">Skip to content</a> 117 118 <header id="masthead" class="site-header" role="banner"> 119 <div class="site-header-main"> 120 <div class="site-branding"> 121 122 <h1 class="site-title"><a href="https://eequalspi.com/" rel="home">e â Ï</a></h1> 123 <p class="site-description">Electronics, Hacking, Stupid Ideas</p> 124 </div><!-- .site-branding --> 125 126 </div><!-- .site-header-main --> 127 128 <div class="header-image"> 129 <a href="https://eequalspi.com/" rel="home"> 130 <img src="https://eequalspi.com/wp-content/uploads/2017/02/cropped-2013-05-02-21.46.07.jpg" srcset="https://eequalspi.com/wp-content/uploads/2017/02/cropped-2013-05-02-21.46.07-300x70.jpg 300w, https://eequalspi.com/wp-content/uploads/2017/02/cropped-2013-05-02-21.46.07-768x179.jpg 768w, https://eequalspi.com/wp-content/uploads/2017/02/cropped-2013-05-02-21.46.07-1024x239.jpg 1024w, https://eequalspi.com/wp-content/uploads/2017/02/cropped-2013-05-02-21.46.07.jpg 1200w" sizes="(max-width: 709px) 85vw, (max-width: 909px) 81vw, (max-width: 1362px) 88vw, 1200px" width="1200" height="280" alt="e â Ï"> 131 </a> 132 </div><!-- .header-image --> 133 </header><!-- .site-header --> 134 135 <div id="content" class="site-content"> 136 137 <div id="primary" class="content-area"> 138 <main id="main" class="site-main" role="main"> 139 140 141 142 143<article id="post-347" class="post-347 post type-post status-publish format-standard hentry category-uncategorized"> 144 <header class="entry-header"> 145 146 <h2 class="entry-title"><a href="https://eequalspi.com/index.php/2022/07/14/pyle-pp444/" rel="bookmark">Pyle PP444</a></h2> </header><!-- .entry-header --> 147 148 149 150 <div class="entry-content"> 151 152<p class="wp-block-paragraph">A few weeks ago, I was looking to hook my turntable up to a new receiver. Previously, it had been hooked up to a 70’s classic, the <a href="https://classicreceivers.com/kenwood-kr-2090">Kenwood KR-2090</a>. As much as the linked review rags on it, this receiver has served me really well, and it’s built in phono preamp sounded really nice to my ear.</p> 153 154 155 156<p class="wp-block-paragraph">My new receiver is a 90’s era, low end Sony unit. Being from the 90’s, it lacks any phono preamp. As such, I needed to get a discrete unit. I don’t consider myself an audiophile, so after reading the customer reviews, I decided to go with a cheapo model, the <a href="https://www.amazon.com/gp/product/B004HJ1TTQ/">Pyle PP444</a> (don’t worry, I stripped the affiliate links, so I don’t get a commission or anything). At first listen, I was happy that it ‘worked’ — the gain was about right and it sounded vaguely OK. The more I listened to records, the more it sounded ‘off’ to me, however. I’m not an audiophile, however, and I can’t claim to have a golden ear (I have a tin one, really).</p> 157 158 159 160<p class="wp-block-paragraph">Anyway, this was an excuse to see if I was right, and better yet, an excuse to use my <a href="https://www.thinksrs.com/products/sr780.html">SR780</a>. </p> 161 162 163 164<figure class="wp-block-image size-large is-resized"><img fetchpriority="high" decoding="async" src="http://eequalspi.com/w
164p-content/uploads/2022/07/Image_20220713_104219-1024x768.jpeg" alt="" class="wp-image-348" width="532" height="398" srcset="https://eequalspi.com/wp-content/uploads/2022/07/Image_20220713_104219-1024x768.jpeg 1024w, https://eequalspi.com/wp-content/uploads/2022/07/Image_20220713_104219-300x225.jpeg 300w, https://eequalspi.com/wp-content/uploads/2022/07/Image_20220713_104219-768x576.jpeg 768w, https://eequalspi.com/wp-content/uploads/2022/07/Image_20220713_104219-1536x1152.jpeg 1536w, https://eequalspi.com/wp-content/uploads/2022/07/Image_20220713_104219-2048x1536.jpeg 2048w, https://eequalspi.com/wp-content/uploads/2022/07/Image_20220713_104219-1200x900.jpeg 1200w, http://eequalspi.com/wp-content/uploads/2022/07/Image_20220713_104219-scaled.jpeg 2560w" sizes="(max-width: 532px) 85vw, 532px" /></figure> 165 166 167 168<p class="wp-block-paragraph">I decided to do a comparison. Using a 10mV input signal and a 20Hz to 20kHz log-spaced sweep, I generated the responses for both the Kenwood and the Pyle PP444 (seen below, compared to the reference RIAA equalization curve). I’ve normalized all three responses to 0dB at 20Hz to simplify comparison.</p> 169 170 171 172<figure class="wp-block-image size-large is-style-zoooom"><img decoding="async" width="1024" height="305" src="http://eequalspi.com/wp-content/uploads/2022/07/Response_Curves_Simplified-1024x305.png" alt="" class="wp-image-349" srcset="https://eequalspi.com/wp-content/uploads/2022/07/Response_Curves_Simplified-1024x305.png 1024w, https://eequalspi.com/wp-content/uploads/2022/07/Response_Curves_Simplified-300x89.png 300w, https://eequalspi.com/wp-content/uploads/2022/07/Response_Curves_Simplified-768x229.png 768w, https://eequalspi.com/wp-content/uploads/2022/07/Response_Curves_Simplified-1536x458.png 1536w, https://eequalspi.com/wp-content/uploads/2022/07/Response_Curves_Simplified-2048x610.png 2048w, https://eequalspi.com/wp-content/uploads/2022/07/Response_Curves_Simplified-1200x358.png 1200w, http://eequalspi.com/wp-content/uploads/2022/07/Response_Curves_Simplified.png 2154w" sizes="(max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px" /></figure> 173 174 175 176<p class="wp-block-paragraph">Sure enough, the Kenwood (blue line) perfectly follows the official RIAA curve (yellow line), while the Pyle (orange line) rolls off way more slowly. Even at 1kHz, the Pyle is about 12dB louder relative to 20Hz deep bass than it should be. No wonder things sound tinny!</p> 177 178 179 180<p class="wp-block-paragraph">I guess the summary is that I shouldn’t have expected much from a $13.20 (at press time) preamp, but nonetheless, I feel like I don’t have a good way to be sure if I’m getting one that actually delivers the response I want at any pricepoint.</p> 181 182 183 184<p class="wp-block-paragraph">I guess the summary is, if you care about sound quality, avoid the PP444. If you just want something that will ‘work’, I guess it’s fine.</p> 185 </div><!-- .entry-content --> 186 187 <footer class="entry-footer"> 188 <span class="byline"><span class="author vcard"><img alt='' src='https://secure.gravatar.com/avatar/e9a139e10fb91ac23ce9e30dc5c5f06e0ebeed3ce543b00735e0a3ad11f638f8?s=49&d=mm&r=g' srcset='https://secure.gravatar.com/avatar/e9a139e10fb91ac23ce9e30dc5c5f06e0ebeed3ce543b00735e0a3ad11f638f8?s=98&d=mm&r=g 2x' class='avatar avatar-49 photo' height='49' width='49' decoding='async'/><span class="screen-reader-text">Author </span> <a class="url fn n" href="https://eequalspi.com/index.php/author/thejbw/">thejbw</a></span></span><span class="posted-on"><span class="screen-reader-text">Posted on </span><a href="https://eequalspi.com/index.php/2022/07/14/pyle-pp444/" rel="bookmark"><time class="entry-date published" datetime="2022-07-14T21:43:17-07:00">July 14, 2022</time><time class="updated" datetime="2022-07-14T21:48:37-07:00">July 14, 2022</time></a></span><span class="cat-links"><span class="screen-reader-text">Categories </span><a href="https://eequalspi.com/index.php/category/uncategorized/" rel="category tag">Uncategorized</a></span> </footer><!-- .entry-footer --> 189</article><!-- #post-347 --> 190 191<article id="post-342" class="post-342 post type-post status-publish format-standard hentry category-uncategorized"> 192 <header class="entry-header"> 193 194 <h2 class="entry-title"><a href="https://eequalspi.com/index.php/2021/03/13/pivideomusic/" rel="bookmark">PiVideoMusic</a></h2> </header><!-- .entry-header --> 195 196 197 198 <div class="entry-content"> 199 200<figure class="wp-block-image size-large"><img decoding="async" src="https://i.imgur.com/Stqb5ZV.png" alt=""/><figcaption>Still shot</figcaption></figure> 201 202 203 204<figure class="wp-block-embed is-type-rich is-provider-embed-handler wp-block-embed-embed-handler"><div class="wp-block-embed__wrapper"> 205<div style="width: 640px;" class="wp-video"><video class="wp-video-shortcode" id="video-342-1" width="640" height="360" preload="metadata" controls="controls"><source type="video/mp4" src="https://i.imgur.com/NZDQjBa.mp4?_=1" /><a href="https://i.imgur.com/NZDQjBa.mp4">https://i.imgur.com/NZDQjBa.mp4</a></video></div> 206</div><figcaption>Silent clip of the PVM in action. Youtube linked below.</figcaption></figure> 207 208 209 210<p class="wp-block-paragraph">Years and years ago, I heard about the AtariVideoMusic. A short lived music visualization device created by Atari in the late 70’s. It would hook up to your home hi-fi and living room TV and show off the music. <a href="https://www.youtube.com/watch?v=wle0eqBwtL8">Techmoan did a good introduction to it here</a>, but imagine a very primitive version of <a href="https://en.wikipedia.org/wiki/MilkDrop">MilkDrop</a>.</p> 211 212 213 214<p class="wp-block-paragraph">Anyway, since before the time Techmoan did his review, I have been thinking about creating my own, modern-retro take on the idea. Music visualizers seem to have dropped off the face of the earth in the last few years, but I’ve always loved them.</p> 215 216 217 218<p class="wp-block-paragraph">Anyway, long story short, a couple of years ago I started making my own. I realized that the Raspberry Pi was the perfect tool for the job. It could easily do all the music visualization I wanted it to, and be built into the stereo component style box with an integrated, tiny, CRT that I envisioned at the time. Fate would have it that my old academic advisor had a tiny portable color television that he gave to me, gratis, and in the course of developing the code, I decided that the TV itself was perfect, so I just put the Raspberry Pi out of sight behind the TV and called
218it a day.</p> 219 220 221 222<h2 class="wp-block-heading">Video Tour</h2> 223 224 225 226<figure class="wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio"><div class="wp-block-embed__wrapper"> 227<iframe loading="lazy" title="PiVideoMusic" width="840" height="473" src="https://www.youtube.com/embed/Tn089Cl4c8I?feature=oembed" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe> 228</div></figure> 229 230 231 232<h2 class="wp-block-heading">Software</h2> 233 234 235 236<p class="wp-block-paragraph">The software is all written in python, and can be <a href="https://github.com/wespo/RaspberryVideoMusic">found here</a>.</p> 237 238 239 240<p class="wp-block-paragraph">There are two files, <code>RaspberryVideoMusicSupervisor.py</code> and <code>RaspberryVideoMusic.py</code>. The former simply makes sure the latter is running as a process. It allows me to automatically recover from the occasional crash and I have set up my Pi to simply launch that script on boot.</p> 241 242 243 244<p class="wp-block-paragraph"><code>RaspberryVideoMusic.py</code> is the main script. It relies on Pygame and Pyaudio. The basic loop is simple. Pyaudio captures audio frames and raises a flag when there’s new data. </p> 245 246 247 248<p class="wp-block-paragraph">There are some basic data ‘services’ available at all times, updated when new data is available. These include things like the audio frame, an FFT of the audio, and a detected signal envelope.</p> 249 250 251 252<p class="wp-block-paragraph">The main loop updates the Pygame display when new data is available. Every few seconds it randomly selects a different foreground and background visualization as well as randomly selected color schemes for each.</p> 253 254 255 256<h2 class="wp-block-heading">
256Hardware</h2> 257 258 259 260<p class="wp-block-paragraph">The hardware is extremely simple. The display is a portable color CRT TV with a composite input. The audio input is a cheap USB sound card. The only trick is that the Raspberry Pi composite output tends to inject audible display noise into the audio. I fixed that by adding a USB isolator between the Pi and the USB sound card.</p> 261 262 263 264<p class="wp-block-paragraph">Additionally, because the sound card input is a mono mic input, it shorts the left and right channels together, creating a mono signal. That’s fine for the visualizer (it could pretty easily be hacked to handle stereo input), but it means that there should be a headphone amp between your signal source and the mic input to prevent the Pi from distorting your sound and making it mono.</p> 265 </div><!-- .entry-content --> 266 267 <footer class="entry-footer"> 268 <span class="byline"><span class="author vcard"><img alt='' src='https://secure.gravatar.com/avatar/e9a139e10fb91ac23ce9e30dc5c5f06e0ebeed3ce543b00735e0a3ad11f638f8?s=49&d=mm&r=g' srcset='https://secure.gravatar.com/avatar/e9a139e10fb91ac23ce9e30dc5c5f06e0ebeed3ce543b00735e0a3ad11f638f8?s=98&d=mm&r=g 2x' class='avatar avatar-49 photo' height='49' width='49' loading='lazy' decoding='async'/><span class="screen-reader-text">Author </span> <a class="url fn n" href="https://eequalspi.com/index.php/author/thejbw/">thejbw</a></span></span><span class="posted-on"><span class="screen-reader-text">Posted on </span><a href="https://eequalspi.com/index.php/2021/03/13/pivideomusic/" rel="bookmark"><time class="entry-date published updated" datetime="2021-03-13T18:19:36-08:00">March 13, 2021</time></a></span><span class="cat-links"><span class="screen-reader-text">Categories </span><a href="https://eequalspi.com/index.php/category/uncategorized/" rel="category tag">Uncategorized</a></span> </footer><!-- .entry-footer --> 269</article><!-- #post-342 --> 270 271<article id="post-333" class="post-333 post type-post status-publish format-standard hentry category-uncategorized"> 272 <header class="entry-header"> 273 274 <h2 class="entry-title"><a href="https://eequalspi.com/index.php/2020/07/26/classic-led-displays/" rel="bookmark">Classic LED Displays</a></h2> </header><!-- .entry-header --> 275 276 277 278 <div class="entry-content"> 279 280<figure class="wp-block-image"><img decoding="async" src="https://i.imgur.com/uS4sAbL.jpg" alt=""/><figcaption>Four LED Displays that we’re about to tour.</figcaption></figure> 281 282 283 284<p class="wp-block-paragraph">Recently on the electronics subreddits, there was a series of posts by people showing off their collections of unique old display modules. I realized that I had quite a few sitting in boxes. Unlike a lot of the posts on Reddit, I am also able to power them on to show off the goods. Enjoy!</p> 285 286 287 288<figure class="wp-block-embed-imgur wp-block-embed is-type-rich is-provider-imgur"><div class="wp-block-embed__wrapper"> 289<blockquote class="imgur-embed-pub" lang="en" data-id="a/xiJaOSs"><a href="https://imgur.com/a/xiJaOSs">My Interesting LED Displays</a></blockquote>
289<script async src="//s.imgur.com/min/embed.js" charset="utf-8"></script>
289 290</div></figure> 291 </div><!-- .entry-content --> 292 293 <footer class="entry-footer"> 294 <span class="byline"><span class="author vcard"><img alt='' src='https://secure.gravatar.com/avatar/e9a139e10fb91ac23ce9e30dc5c5f06e0ebeed3ce543b00735e0a3ad11f638f8?s=49&d=mm&r=g' srcset='https://secure.gravatar.com/avatar/e9a139e10fb91ac23ce9e30dc5c5f06e0ebeed3ce543b00735e0a3ad11f638f8?s=98&d=mm&r=g 2x' class='avatar avatar-49 photo' height='49' width='49' loading='lazy' decoding='async'/><span class="screen-reader-text">Author </span> <a class="url fn n" href="https://eequalspi.com/index.php/author/thejbw/">thejbw</a></span></span><span class="posted-on"><span class="screen-reader-text">Posted on </span><a href="https://eequalspi.com/index.php/2020/07/26/classic-led-displays/" rel="bookmark"><time class="entry-date published updated" datetime="2020-07-26T17:00:21-07:00">July 26, 2020</time></a></span><span class="cat-links"><span class="screen-reader-text">Categories </span><a href="https://eequalspi.com/index.php/category/uncategorized/" rel="category tag">Uncategorized</a></span> </footer><!-- .entry-footer --> 295</article><!-- #post-333 --> 296 297<article id="post-308" class="post-308 post type-post status-publish format-standard hentry category-clocks category-code category-nixie category-python category-uncategorized category-uniac tag-nixie tag-python tag-raspberrypi tag-raspotify tag-spotify tag-spotipy tag-uniac"> 298 <header class="entry-header"> 299 300 <h2 class="entry-title"><a href="https://eequalspi.com/index.php/2020/05/30/making-a-raspberry-pi-boombox-aka-uniac-software-in-detail/" rel="bookmark">Making a Raspberry Pi Boombox (AKA UNIAC Software In Detail)</a></h2> </header><!-- .entry-header --> 301 302 303 304 <div class="entry-content"> 305 306<figure class="wp-block-image size-large"><img loading="lazy" decoding="async" width="1024" height="439" src="http://eequalspi.com/wp-content/uploads/2020/04/image-1-1024x439.png" alt="" class="wp-image-282" srcset="https://eequalspi.com/wp-content/uploads/2020/04/image-1-1024x439.png 1024w, https://eequalspi.com/wp-content/uploads/2020/04/image-1-300x128.png 300w, https://eequalspi.com/wp-content/uploads/2020/04/image-1-768x329.png 768w, https://eequalspi.com/wp-content/uploads/2020/04/image-1-1536x658.png 1536w, https://eequalspi.com/wp-content/uploads/2020/04/image-1-2048x877.png 2048w, https://eequalspi.com/wp-content/uploads/2020/04/image-1-1200x514.png 1200w, http://eequalspi.com/wp-content/uploads/2020/04/image-1.png 3302w" sizes="auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px" /></figure> 307 308 309 310<h2 class="wp-block-heading">Introduction</h2> 311 312 313 314<p class="wp-block-paragraph">Most of you who see this post will have seen the <a href="http://eequalspi.com/index.php/2020/04/04/uniac-the-ultimate-nixie-internet-alarm-clock/">original UNIAC post </a>before this, and hopefully some will have seen the <a href="http://eequalspi.com/index.php/2020/05/16/uniac-hardware-in-detail/">post detailing the hardware</a>. For those who haven’t, UNIAC is a Raspberry Pi based Spotify playing boombox that is controlled with buttons on the front and displays status using Nixie tubes. This post will cover the software used to make UNIAC work — both tools developed by others and the software I wrote myself.</p> 315 316 317 318<p class="wp-block-paragraph"><strong>While I am writing this from the perspective of documenting UNIAC, the software could be pretty easily recycled to work with any display and buttons, you’d just have to rewrite the display and button event functions to support your hardware.</strong></p> 319 320 321 322<p class="wp-block-paragraph">Also note that I did a <a href="http://eequalspi.com/index.php/2020/04/18/refactoring-the-uniac-playback-code/">major ripup of the UNIAC software</a> after the original post, so this version does not use Mopidy, MPD, or Mopidy-Spotify. And if any of you have used those tools before, you’ll understand that’s a good thing.</p> 323 324 325 326<p class="wp-block-paragraph">I will start with a disclaimer however: I am an electrical engineer, not a software engineer, so this design will probably make softw
326are guys sick to their stomach. Sorry in advance…</p> 327 328 329 330<h2 class="wp-block-heading">Third Party Software</h2> 331 332 333 334<p class="wp-block-paragraph">The first thing to understand about the architecture used in UNIAC is that control and playback of music are two separate processes. <a href="https://github.com/dtcooper/raspotify">Raspotify</a> is a software package that connects to Spotify and makes your RPi act as a Spotify endpoint. Essentially a dedicated speaker. There are a couple of similar packages that can give you a Spotify client on a RPi, but Raspotify has a trivial installation process:</p> 335 336 337 338<pre class="wp-block-code"><code>curl -sL https://dtcooper.github.io/raspotify/install.sh | sh</code></pre> 339 340 341 342<p class="wp-block-paragraph">The second part, <a href="https://spotipy.readthedocs.io/en/2.12.0/">Spotipy</a>, is a Python library that you give permissions on your (paid) Spotify account. It allows you to see current playback status, and control playback on your Spotify devices (computers, speakers, etc). By combining these two, you can have a full Spotify instance running on your device with programmable control.</p> 343 344 345 346<p class="wp-block-paragraph">The two pieces are connected by the UNIAC Python script. UNIAC sets up a spotipy connection and then controls what device the playback occurs on. Since the name of the UNIAC Raspotify instance is constant, it simply has to tell Spotify to playback there, and music will play on the UNIAC hardware. This has the added benefit that I can ‘cast’ whatever I’m currently listening to over to UNIAC and it will just continue to play.</p> 347 348 349 350<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/05/image-10-1024x393.png" alt="" class="wp-image-329" width="622" height="238" srcset="https://eequalspi.com/wp-content/uploads/2020/05/image-10-1024x393.png 1024w, https://eequalspi.com/wp-content/uploads/2020/05/image-10-300x115.png 300w, https://eequalspi.com/wp-content/uploads/2020/05/image-10-768x294.png 768w, https://eequalspi.com/wp-content/uploads/2020/05/image-10-1536x589.png 1536w, https://eequalspi.com/wp-content/uploads/2020/05/image-10-2048x785.png 2048w, https://eequalspi.com/wp-content/uploads/2020/05/image-10-1200x460.png 1200w, http://eequalspi.com/wp-content/uploads/2020/05/image-10.png 2345w" sizes="auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 984px) 61vw, (max-width: 1362px) 45vw, 600px" /><figcaption>UNIAC / Spotify control.</figcaption></figure> 351 352 353 354<p class="wp-block-paragraph">The last piece worth mentioning is <a href="http://espeak.sourceforge.net/">eSpeak</a>, a relatively primitive speech synthesizer that takes strings from the command line and announces them. This lends UNIAC its characteristic robot voice when announcing settings information and playlist names.</p> 355 356 357 358<h2 class="wp-block-heading">
358Hardware Libraries</h2> 359 360 361 362<div class="wp-block-image"><figure class="aligncenter size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/05/image-11-1024x677.png" alt="" class="wp-image-330" width="360" height="237" srcset="https://eequalspi.com/wp-content/uploads/2020/05/image-11-1024x677.png 1024w, https://eequalspi.com/wp-content/uploads/2020/05/image-11-300x198.png 300w, https://eequalspi.com/wp-content/uploads/2020/05/image-11-768x508.png 768w, https://eequalspi.com/wp-content/uploads/2020/05/image-11-1200x794.png 1200w, https://eequalspi.com/wp-content/uploads/2020/05/image-11.png 1240w" sizes="auto, (max-width: 360px) 85vw, 360px" /><figcaption>Path between the controls, the Display, and UNIAC.</figcaption></figure></div> 363 364 365 366<p class="wp-block-paragraph">The hardware interfaces are pretty straightforward, mostly. The buttons are controlled by an i2c GPIO expander, and Adafruit has the <a href="https://learn.adafruit.com/mcp230xx-gpio-expander-on-the-raspberry-pi/using-the-library">MCP230XX library</a> to support it. For other GPIO, I use <a href="https://pypi.org/project/RPi.GPIO/">RPi.GPIO</a>.</p> 367 368 369 370<p class="wp-block-paragraph">The last, and most unique library is the NixieDisplay library. It is a <a href="https://github.com/wespo/NixieDisplay">custom library that I developed</a> to communicate with my Teensy 3.2 based multiplexing, crossfading Nixie display. In the first prototype, I used Taylor Edge SmartNixie modules instead of my custom display, so <a href="https://github.com/wespo/SmartNixie">I also wrote a library supporting them</a> on the RPi, though I’m not using it on the finished version.</p> 371 372 373 374<p class="wp-block-paragraph">These libraries are pretty straightforward. You print numbers to the tubes to display and forget about it.</p> 375 376 377 378<p class="wp-block-paragraph">The VU-Meter only has an audio input, so it doesn’t have any software control and doesn’t appear on any of these block diagrams.</p> 379 380 381 382<h2 class="wp-block-heading">UNIAC Software Architecture</h2> 383 384 385 386<p class="wp-block-paragraph"><a href="https://github.com/wespo/UNIAC">The UNIAC software</a> is essentially an interrupt driven button handler. There is a master ‘Menu’ class in <a href="https://github.com/wespo/UNIAC/blob/master/Menu.py">Menu.py</a> to which arbitrary ‘Modes’ are attached. An attached mode must provide a function handler for each physical button as well as a display update handler (and a few other helper functions).</p> 387 388 389 390<p class="wp-block-paragraph">When a button is pressed, the Menu object calls the current Mode’s handler for that button.</p> 391 392 393 394<div class="wp-block-image"><figure class="aligncenter size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/05/image-4.png" alt="" class="wp-image-318" width="222" height="152" srcset="https://eequalspi.com/wp-content/uploads/2020/05/image-4.png 812w, https://eequalspi.com/wp-content/uploads/2020/05/image-4-300x206.png 300w, https://eequalspi.com/wp-content/uploads/2020/05/image-4-768x528.png 768w" sizes="auto, (max-width: 222px) 85vw, 222px" /><figcaption>Button Press Event</figcaption></figure></div> 395 396 397 398<p class="wp-block-paragraph">The <a href="https://github.com/wespo/UNIAC/blob/master/UNIAC.py">UNIAC.py</a> script creates a Menu instance and attaches the modes defined in that script. The modes (currently) are: clock, track time, date, alarm clock, change playlist, and options. </p> 399 400 401 402<div class="wp-block-image"><figure class="aligncenter size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/05/image-5-1024x366.png" alt="" class="wp-image-319" width="411" height="146" srcset="https://eequalspi.com/wp-content/uploads/2020/05/image-5-1024x366.png 1024w, https://eequalspi.com/wp-content/uploads/2020/05/image-5-300x107.png 300w, https://eequalspi.com/wp-content/uploads/2020/05/image-5-768x275.png 768w, https://eequalspi.com/wp-content/uploads/2020/05/image-5-1200x429.png 1200w, https://eequalspi.com/w
402p-content/uploads/2020/05/image-5.png 1494w" sizes="auto, (max-width: 411px) 85vw, 411px" /><figcaption>Modes attached to Menu in UNIAC.py</figcaption></figure></div> 403 404 405 406<p class="wp-block-paragraph">For instance, when the ‘Plus’ button is pressed in the track time mode, the menu object will use Spotipy to progress to the next track, but when ‘Plus’ is pressed in the alarm mode, it will advance the alarm time by one.</p> 407 408 409 410<p class="wp-block-paragraph">The ‘Mode’ button is a special case that does not call an attached handler function but instead changes the selected mode in the Menu object.</p> 411 412 413 414<p class="wp-block-paragraph">The Menu object also requires that each mode have a display update handler. This handler is called by the master UNIAC.py script in an infinte loop to update the display every 100 ms.</p> 415 416 417 418<div class="wp-block-image"><figure class="aligncenter size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/05/image-3.png" alt="" class="wp-image-317" width="296" height="62" srcset="https://eequalspi.com/wp-content/uploads/2020/05/image-3.png 818w, https://eequalspi.com/wp-content/uploads/2020/05/image-3-300x64.png 300w, https://eequalspi.com/wp-content/uploads/2020/05/image-3-768x163.png 768w" sizes="auto, (max-width: 296px) 85vw, 296px" /><figcaption>Display Updater</figcaption></figure></div> 419 420 421 422<p class="wp-block-paragraph">This code was actually based off of another (unfinished) project of mine which used two buttons and a character LCD. By changing the displayUpdate function and the button handlers, this script could be used for virtually any menu interface with multiple ‘pages’.</p> 423 424 425 426<h2 class="wp-block-heading">Interfacing with Spotipy</h2> 427 428 429 430<p class="wp-block-paragraph">As discussed in the preceeding section, UNIAC is controlled through a series of button handlers. To interface with Spotipy, most of the modes used in UNIAC inherit from the mpdGeneral class.</p> 431 432 433 434<div class="wp-block-image"><figure class="aligncenter size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/05/image-6-1024x507.png" alt="" class="wp-image-320" width="402" height="198" srcset="https://eequalspi.com/wp-content/uploads/2020/05/image-6-1024x507.png 1024w, https://eequalspi.com/wp-content/uploads/2020/05/image-6-300x148.png 300w, https://eequalspi.com/wp-content/uploads/2020/05/image-6-768x380.png 768w, https://eequalspi.com/wp-content/uploads/2020/05/image-6.png 1184w" sizes="auto, (max-width: 402px) 85vw, 402px" /><figcaption>mpdGeneral class definition</figcaption></figure></div> 435 436 437 438<p class="wp-block-paragraph">This class has a few static variables and references the globally available spotipyLogin.sp object, which is an instance of the bare Spotipy API created by the spotipyLogin.py script. It includes things like track status, play, pause, loading a defined playlist from URI, listing available playlists, et cetera.</p> 439 440 441 442<p class="wp-block-paragraph">The UNIACConfig class allows settings like alarm time, current playlist, and settings to be pickled to a config file and loaded on restart. The other classes (including the option menu mode) use this class to handle i/o to the settings file, ‘UNIAC.conf’.</p> 443 444 445 446<div class="wp-block-image"><figure class="aligncenter size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/05/image-7-1024x977.png" alt="" class="wp-image-321" width="349" height="332" srcset="https://eequalspi.com/wp-content/uploads/2020/05/image-7-1024x977.png 1024w, https://eequalspi.com/wp-content/uploads/2020/05/image-7-300x286.png 300w, https://eequalspi.com/wp-content/uploads/2020/05/image-7-768x733.png 768w, https://eequalspi.com/wp-content/uploads/2020/05/image-7.png 1130w" sizes="auto, (max-width: 349px) 85vw, 349px" /><figcaption>UNIACConfig class.</figcaption></figure></div> 447 448 449 450<p class="wp-block-paragraph">The remainder of the classes are more or less straightforward implementations of their self explanatory modes and hook the various parts and pieces together.</p> 451 452 453 454<p class="wp-block-paragraph">The last piece of secret sauce, <strong>which is not on git,</strong> because it is in m gitignore is spotipyLogin.py, a simple script which holds my Spotify login credentials and makes a logged in Spotipy object available.</p> 455 456 457 458<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/w
458p-content/uploads/2020/05/image-8-1024x900.png" alt="" class="wp-image-322" width="468" height="411" srcset="https://eequalspi.com/wp-content/uploads/2020/05/image-8-1024x900.png 1024w, https://eequalspi.com/wp-content/uploads/2020/05/image-8-300x264.png 300w, https://eequalspi.com/wp-content/uploads/2020/05/image-8-768x675.png 768w, https://eequalspi.com/wp-content/uploads/2020/05/image-8-1536x1351.png 1536w, https://eequalspi.com/wp-content/uploads/2020/05/image-8-2048x1801.png 2048w, https://eequalspi.com/wp-content/uploads/2020/05/image-8-1200x1055.png 1200w, http://eequalspi.com/wp-content/uploads/2020/05/image-8.png 2104w" sizes="auto, (max-width: 468px) 85vw, 468px" /><figcaption>The redacted version of spotipyLogin.py</figcaption></figure> 459 460 461 462<h2 class="wp-block-heading">UNIAC Supervisor</h2> 463 464 465 466<p class="wp-block-paragraph">Finally, there is a UNIAC supervisor script. This is an independent Python process which checks if the UNIAC script is running and if not launches it. It also checks that only one instance of the script is running, and if a second copy has started somehow, kills all but the first process. It’s not strictly necessary, but is a nice-to-have feature. I ran without it for years, with only occasional failures.</p> 467 468 469 470<div class="wp-block-image"><figure class="aligncenter size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/05/image-9-1024x376.png" alt="" class="wp-image-323" width="506" height="185" srcset="https://eequalspi.com/wp-content/uploads/2020/05/image-9-1024x376.png 1024w, https://eequalspi.com/wp-content/uploads/2020/05/image-9-300x110.png 300w, https://eequalspi.com/wp-content/uploads/2020/05/image-9-768x282.png 768w, https://eequalspi.com/wp-content/uploads/2020/05/image-9-1536x564.png 1536w, https://eequalspi.com/wp-content/uploads/2020/05/image-9-2048x752.png 2048w, https://eequalspi.com/wp-content/uploads/2020/05/image-9-1200x440.png 1200w, http://eequalspi.com/wp-content/uploads/2020/05/image-9.png 2708w" sizes="auto, (max-width: 506px) 85vw, 506px" /><figcaption>UNIAC supervisor script.</figcaption></figure></div> 471 472 473 474<h2 class="wp-block-heading">Conclusion</h2> 475 476 477 478<p class="wp-block-paragraph">The UNIAC software is a combination of several bits and pieces of code which allows a button driven paged menu system to control the Spotify web API and stream music for plaback locally on the RPi, as if it were a commercial product. The interface is ideally suited to a ‘Nixie Boombox’ but could be used with any oddball display you wanted with a little modification.</p> 479 480 481 482<p class="wp-block-paragraph">Thanks for reading.</p> 483 </div><!-- .entry-content --> 484 485 <footer class="entry-footer"> 486 <span class="byline"><span class="author vcard"><img alt='' src='https://secure.gravatar.com/avatar/e9a139e10fb91ac23ce9e30dc5c5f06e0ebeed3ce543b00735e0a3ad11f638f8?s=49&d=mm&r=g' srcset='https://secure.gravatar.com/avatar/e9a139e10fb91ac23ce9e30dc5c5f06e0ebeed3ce543b00735e0a3ad11f638f8?s=98&d=mm&r=g 2x' class='avatar avatar-49 photo' height='49' width='49' loading='lazy' decoding='async'/><span class="screen-reader-text">Author </span> <a class="url fn n" href="https://eequalspi.com/index.php/author/thejbw/">thejbw</a></span></span><span class="posted-on"><span class="screen-reader-text">Posted on </span><a href="https://eequalspi.com/index.php/2020/05/30/making-a-raspberry-pi-boombox-aka-uniac-software-in-detail/" rel="bookmark"><time class="entry-date published updated" datetime="2020-05-30T15:47:37-07:00">May 30, 2020</time></a></span><span class="cat-links"><span class="screen-reader-text">Categories </span><a href="https://eequalspi.com/index.php/category/clocks/" rel="category tag">Clocks</a>, <a href="https://eequalspi.com/index.php/category/code/" rel="category tag">Code</a>, <a href="https://eequalspi.com/index.php/category/nixie/" rel="category tag">Nixie</a>, <a href="https://eequalspi.com/index.php/category/python/" rel="category tag">Python</a>, <a href="https://eequalspi.com/index.php/category/uncategorized/" rel="category tag">Uncategorized</a>, <a href="https://eequalspi.com/index.php/category/uniac/" rel="category tag">UNIAC</a></span><span class="tags-links"><span class="screen-reader-text">Tags </span><a href="https://eequalspi.com/index.php/tag/nixie/" rel="tag">Nixie</a>, <a href="https://eequalspi.com/index.php/tag/python/" rel="tag">Python</a>, <a href="https://eequalspi.com/index.php/tag/raspberrypi/" rel="tag">RaspberryPi</a>, <a href="https://eequalspi.com/index.php/tag/raspotify/" rel="tag">Raspotify</a>, <a href="https://eequalspi.com/index.php/tag/spotify/" rel="tag">Spotify</a>, <a href="https://eequalspi.com/index.php/tag/spotipy/" rel="tag">Spotipy</a>, <a href="https://eequalspi.com/index.php/tag/uniac/" rel="tag">UNIAC</a></span> </footer><!-- .entry-footer --> 487</article><!-- #post-308 --> 488 489<article id="post-288" class="post-288 post type-post status-publish format-standard hentry category-clocks category-nixie category-uncategorized category-uniac tag-nixie tag-raspberrypi tag-rpi tag-spotify tag-uniac"> 490 <header class="entry-header"> 491 492 <h2 class="entry-title"><a href="https://eequalspi.com/index.php/2020/05/16/uniac-hardware-in-detail/" rel="bookmark">UNIAC Hardware In Detail</a></h2> </header><!-- .entry-header --> 493 494 495 496 <div class="entry-content"> 497 498<p class="wp-block-paragraph">After sharing my last post on Reddit and Hackaday, I’ve gotten lots of kind feedback — and I deeply, deeply appreciate it all. More than anything else, it makes me regret not sharing this project with you sooner.</p> 499 500 501 502<p class="wp-block-paragraph">That said, the biggest ask has been for a detailed build guide. Unfortuantely, I didn’t document the build process in enough detail to write up a step by step guide, and I
502just don’t have the energy to build an entire new copy right now.</p> 503 504 505 506<p class="wp-block-paragraph">What I <em>can</em> do, however, is share discuss the design choices I made and share the build files. This post will focus on the hardware design of UNIAC, and I will follow it with a post detailing the software in greater detail.</p> 507 508 509 510<h2 class="wp-block-heading">Schematics</h2> 511 512 513 514<p class="wp-block-paragraph">The schematic capture and layout was done in Eagle, and broken out into pages. It’s not perfect, by any means, but it’s clean enough.</p> 515 516 517 518<p class="wp-block-paragraph">Anyway, let’s go through the sections.</p> 519 520 521 522<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/04/FoxitReader_2020-04-28_21-55-16-1024x459.png" alt="" class="wp-image-290" width="624" height="279" srcset="https://eequalspi.com/wp-content/uploads/2020/04/FoxitReader_2020-04-28_21-55-16-1024x459.png 1024w, https://eequalspi.com/wp-content/uploads/2020/04/FoxitReader_2020-04-28_21-55-16-300x134.png 300w, https://eequalspi.com/wp-content/uploads/2020/04/FoxitReader_2020-04-28_21-55-16-768x344.png 768w, https://eequalspi.com/wp-content/uploads/2020/04/FoxitReader_2020-04-28_21-55-16-1536x688.png 1536w, https://eequalspi.com/wp-content/uploads/2020/04/FoxitReader_2020-04-28_21-55-16-2048x917.png 2048w, https://eequalspi.com/wp-content/uploads/2020/04/FoxitReader_2020-04-28_21-55-16-1200x538.png 1200w, http://eequalspi.com/wp-content/uploads/2020/04/FoxitReader_2020-04-28_21-55-16.png 2547w" sizes="auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 984px) 61vw, (max-width: 1362px) 45vw, 600px" /><figcaption>Raspberry Pi, Buttons, Sound Card, Amplifier</figcaption></figure> 523 524 525 526<p class="wp-block-paragraph">This section has:</p> 527 528 529 530<p class="wp-block-paragraph">The Raspberry Pi itself — note that the footprint says “Raspberry Pi Model B+”, but is actually sized for the Pi Zero W. I recycled an existing symbol because the header pinout is the same across both versions of the Pi, and simply forgot to rename it in Eagle. It also specifies a 7805 5V regulator to power the Pi off the input 12V bus. In practice I used a <a href="https://www.digikey.com/product-detail/en/murata-power-solutions-inc/7805SRH-C/811-2644-ND/3438627">drop in switch mode replacement</a> for the 7805 from Murata.</p> 531 532 533 534<p class="wp-block-paragraph">The button interfaces — supports two options to connect buttons. The first one, Buttons A, is for directly connecting to the motherboard. I used this option in the first two prototypes and decided to keep the option open here in case the button breakout board had problems, since I had the board space. The button connections here include a provision for +12V to illuminate the buttons, a shared switched ground line to control button illumination, resistors to pull up the buttons and caps for debounce.</p> 535 536 537 538<p class="wp-block-paragraph">Buttons B is a header for the button board, shown later. It breaks out the I2C bus connected to the RPI as well as a 3.3V rail for powering an offboard IC and a 12V rail for powering button illumination. Finally it has an interrupt pin so that the Pi can detect when the button board needs to be polled.</p> 539 540 541 542<p class="wp-block-paragraph">Finally it has footprints for <a href="https://www.amazon.com/gp/product/B07Q9K5MT8">I2S DAC (sound card)</a> and <a href="https://www.adafruit.com/product/1752">Adafruit class-D amplifier</a>. Not too much to see there. </p> 543 544 545 546<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/04/FoxitReader_2020-04-28_21-44-03-1024x495.png" alt="" class="wp-image-293" width="625" height="302" srcset="https://eequalspi.com/wp-content/uploads/2020/04/FoxitReader_2020-04-28_21-44-03-1024x495.png 1024w, https://eequalspi.com/wp-content/uploads/2020/04/FoxitReader_2020-04-28_21-44-03-300x145.png 300w, https://eequalspi.com/wp-content/uploads/2020/04/FoxitReader_2020-04-28_21-44-03-768x371.png 768w, https://eequalspi.com/w
546p-content/uploads/2020/04/FoxitReader_2020-04-28_21-44-03-1536x743.png 1536w, https://eequalspi.com/wp-content/uploads/2020/04/FoxitReader_2020-04-28_21-44-03-2048x990.png 2048w, https://eequalspi.com/wp-content/uploads/2020/04/FoxitReader_2020-04-28_21-44-03-1200x580.png 1200w, http://eequalspi.com/wp-content/uploads/2020/04/FoxitReader_2020-04-28_21-44-03.png 2453w" sizes="auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 984px) 61vw, (max-width: 1362px) 45vw, 600px" /><figcaption>VU-meter section</figcaption></figure> 547 548 549 550<p class="wp-block-paragraph">The next page of the schematic is a direct copy of my <a href="http://eequalspi.com/index.php/category/in-13-vumeter/">IN-13 VU Meter circuit</a>. I won’t go into a full description of the theory, but it uses a quad rail to rail op-amp to save parts (I usually populate with an LMC660), and MPSA42 high voltage small signal transistors to drive the IN-13s. There is also an ATTINY85 micro <a href="https://github.com/wespo/Nixie_VU_Meter_R02">running this code</a> to make it act as a log converter. This saves parts and board area vs an analog implementation as well as allowing the VU meter to go to sleep if there’s been no audio for a couple of minutes.</p> 551 552 553 554<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/04/eagle_2020-04-28_22-45-48-1024x375.png" alt="" class="wp-image-294" width="627" height="229" srcset="https://eequalspi.com/wp-content/uploads/2020/04/eagle_2020-04-28_22-45-48-1024x375.png 1024w, https://eequalspi.com/wp-content/uploads/2020/04/eagle_2020-04-28_22-45-48-300x110.png 300w, https://eequalspi.com/wp-content/uploads/2020/04/eagle_2020-04-28_22-45-48-768x281.png 768w, https://eequalspi.com/wp-content/uploads/2020/04/eagle_2020-04-28_22-45-48-1536x562.png 1536w, https://eequalspi.com/wp-content/uploads/2020/04/eagle_2020-04-28_22-45-48-2048x749.png 2048w, https://eequalspi.com/wp-content/uploads/2020/04/eagle_2020-04-28_22-45-48-1200x439.png 1200w, http://eequalspi.com/wp-content/uploads/2020/04/eagle_2020-04-28_22-45-48.png 3195w" sizes="auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 984px) 61vw, (max-width: 1362px) 45vw, 600px" /><figcaption>Nixie display section</figcaption></figure> 555 556 557 558<p class="wp-block-paragraph">The third page of the schematic covers the Nixie display. This design was inspired by Dave Jones’ (of EEVBlog) <a href="https://www.youtube.com/watch?v=7uogKucrPks">Nixie tube driver design</a>, which attempts to save transistors by using multi transistor ICs. Ultimately, I’m not very happy with that part of the design as there seems to be enough leakage that minor ghosting is visible on the tubes. I’ll definitely revisit it for my next Nixie project. </p> 559 560 561 562<p class="wp-block-paragraph">The controller for the display is a Teensy 3.2 which accepts commands to display values on the Nixies and INS-1 neon lamps via I2C and supports crossfading between digits.</p> 563 564 565 566<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/04/eagle_2020-04-28_21-59-47-1024x496.png" alt="" class="wp-image-292" width="632" height="306" srcset="https://eequalspi.com/wp-content/uploads/2020/04/eagle_2020-04-28_21-59-47-1024x496.png 1024w, https://eequalspi.com/wp-content/uploads/2020/04/eagle_2020-04-28_21-59-47-300x145.png 300w, https://eequalspi.com/wp-content/uploads/2020/04/eagle_2020-04-28_21-59-47-768x372.png 768w, https://eequalspi.com/wp-content/uploads/2020/04/eagle_2020-04-28_21-59-47-1536x744.png 1536w, https://eequalspi.com/wp-content/uploads/2020/04/eagle_2020-04-28_21-59-47-2048x992.png 2048w, https://eequalspi.com/wp-content/uploads/2020/04/eagle_2020-04-28_21-59-47-1200x581.png 1200w, http://eequalspi.com/wp-content/uploads/2020/04/eagle_2020-04-28_21-59-47.png 2480w" sizes="auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 984px) 61vw, (max-width: 1362px) 45vw, 600px" /><figcaption>Button breakout board</figcaption></figure> 567 568 569 570<p class="wp-block-paragraph">Finally, The button board uses an <a href="https://www.adafruit.com/product/593">I2C GPIO expander IC</a> to provide the same functionality as the individual button headers shown earlier, but without having nearly as many wires. The downside is that it requires an extra IC to do the job, and once the buttons are in the case, they’re soldered to the PCB and are pretty much stuck for good.</p> 571 572 573 574<h2 class="wp-block-heading">Layouts</h2> 575 576 577 578<p class="wp-block-paragraph">The UNIAC mainboard layout is pretty compact. There’s not too much to talk about. Most of the size was defined by the need to have the Nixies at the top, bargraph tubes in the middle, and buttons at the bottom. Except for the routing around the Nixies themselves, there were no space constrained areas. I did choose to put the Teensy and RPi near the edges, so that their USB ports were practically accessible, however.</p> 579 580 581 582<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/w
582p-content/uploads/2020/05/image-1-1024x625.png" alt="" class="wp-image-302" width="482" height="293" srcset="https://eequalspi.com/wp-content/uploads/2020/05/image-1-1024x625.png 1024w, https://eequalspi.com/wp-content/uploads/2020/05/image-1-300x183.png 300w, https://eequalspi.com/wp-content/uploads/2020/05/image-1-768x469.png 768w, https://eequalspi.com/wp-content/uploads/2020/05/image-1-1536x938.png 1536w, https://eequalspi.com/wp-content/uploads/2020/05/image-1-2048x1250.png 2048w, https://eequalspi.com/wp-content/uploads/2020/05/image-1-1200x733.png 1200w, http://eequalspi.com/wp-content/uploads/2020/05/image-1.png 2850w" sizes="auto, (max-width: 482px) 85vw, 482px" /><figcaption>UNIAC Mainboard.</figcaption></figure> 583 584 585 586<p class="wp-block-paragraph">I went to great lengths to calculate minimum creepage distances and trace widths, which I used as design rules to ensure the Nixie display would be safe while being as small as I could make it. When routing my HV traces, I assumed 200 V DC and used a <a href="http://www.creepage.com/">calculator like this one</a>. I ended up using approximately 16mil or 0.4mm as my minimum trace clearance.</p> 587 588 589 590<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/05/image-1024x986.png" alt="" class="wp-image-301" width="529" height="508" srcset="https://eequalspi.com/wp-content/uploads/2020/05/image-1024x986.png 1024w, https://eequalspi.com/wp-content/uploads/2020/05/image-300x289.png 300w, http://eequalspi.com/wp-content/uploads/2020/05/image.png 1034w" sizes="auto, (max-width: 529px) 85vw, 529px" /><figcaption>Closeup of the HV nets for the Nixies.</figcaption></figure> 591 592 593 594<p class="wp-block-paragraph">For trace width, I used <a href="https://www.4pcb.com/trace-width-calculator.html">4PCB’s calculator</a>, and found that even 600 mA would only cause a 10ËC rise for a 6 mil (0.15 mm) wide trace, way more than any of my HV traces were going to carry.vI also chose to keep the ground plane far away from the HV areas for added safety. Given that the Nixies are multiplexed and connect to ground only at a few points, it made sense and decluttered the design.</p> 595 596 597 598<p class="wp-block-paragraph">Finally, we go to the ‘Button Board’. The front panel control buttons are mounted to the front of the case and then soldered to this PCB. It’s a fairly simple design, but it has a couple of notches to clear the standoffs that mount the mainboard and speakers to the case.</p> 599 600 601 602<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/05/image-2-1024x154.png" alt="" class="wp-image-303" width="457" height="69" srcset="https://eequalspi.com/wp-content/uploads/2020/05/image-2-1024x154.png 1024w, https://eequalspi.com/wp-content/uploads/2020/05/image-2-300x45.png 300w, https://eequalspi.com/wp-content/uploads/2020/05/image-2-768x115.png 768w, https://eequalspi.com/wp-content/uploads/2020/05/image-2-1536x231.png 1536w, https://eequalspi.com/wp-content/uploads/2020/05/image-2-2048x308.png 2048w, https://eequalspi.com/wp-content/uploads/2020/05/image-2-1200x180.png 1200w, http://eequalspi.com/wp-content/uploads/2020/05/image-2.png 3182w" sizes="auto, (max-width: 457px) 85vw, 457px" /><figcaption>Button board.</figcaption></figure> 603 604 605 606<p class="wp-block-paragraph">The biggest pain about this board was getting it fabricated. The buttons have wide pins that need to be fabricated as small slots. This is because the pins are so wide and closely spaced that large enough circular holes actually <em>overlap </em>each other. </p> 607 608 609 610<p class="wp-block-paragraph">It took three tries to get the boards fabricated. I had to make sure that the slots were on the correct layer in the footprint and had to specifically reach out to the PCB vendor in advance to ask them to send checkplots to confirm that the board would get fabbed correctly. </p> 611 612 613 614<p class="wp-block-paragraph">The first order was from AllPCB without asking in advance and they simply milled the small circular holes instead of slots. The second time, they promised that they would send me checkplots, but just fabbed the board without doing so. They also ignored my customer complaint.</p> 615 616 617 618<p class="wp-block-paragraph">It was at that point that I switched to PCBWay, who provided checkplots as requested, but they actually had the slots correct on the first try, resulting in great boards. My only regret is that their matte black soldermask is slightly shinier than AllPCB’s so the boards don’t <em>quite</em> match the mainboard.</p> 619 620 621 622<p class="wp-block-paragraph"><a href="http://eequalspi.com/attachments/UNIAC%20Boards.zip">The Eagle files for the switch board and main board can be found here.</a></p> 623 624 625 626<h2 class="wp-block-heading">BOM</h2> 627 628 629 630<p class="wp-block-paragraph">The bill of materials, that is, the list of all the components used, is fairly long. It lists all the components that go on the main board, as well as the button board, and all of the off board components that I could think of. Since it’s a big, ugly table, I’m just going to attach it as a csv. The major parts themselves are detailed in the <a href="http://eequalspi.com/index.php/2020/04/04/uniac-the-ultimate-nixie-internet-alarm-clock/?preview_id=219&preview_nonce=04a20b4cb6&preview=true">first UNIAC post</a>.</p> 631 632 633 634<p class="wp-block-paragraph"><a href="http://eequalspi.com/attachments/BOM.xlsx">Anyway, the full BOM can be found here.</a></p> 635 636 637 638<h2 class="wp-block-heading">Enclosure</h2> 639 640 641 642<p class="wp-block-paragraph">Making the enclosure was a blast. My workflow is terrible and costs me several pieces of plastic on each new design I come up with, to be honest. I design the acrylic pieces as 2D Inkscape images and handle the ‘3D Modeling’ in my head. It’s even lower rent than DaveCAD!</p> 643 644 645 646<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/w
646p-content/uploads/2020/05/Enclosure_Reference_Front.png" alt="" class="wp-image-305" width="499" height="325" srcset="https://eequalspi.com/wp-content/uploads/2020/05/Enclosure_Reference_Front.png 853w, https://eequalspi.com/wp-content/uploads/2020/05/Enclosure_Reference_Front-300x196.png 300w, https://eequalspi.com/wp-content/uploads/2020/05/Enclosure_Reference_Front-768x501.png 768w" sizes="auto, (max-width: 499px) 85vw, 499px" /><figcaption>Front Panel. Bent along the red horizontal lines which are not visible in finished enclosure.</figcaption></figure> 647 648 649 650<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/05/Enclosure_Reference_Back.png" alt="" class="wp-image-306" width="504" height="127" srcset="https://eequalspi.com/wp-content/uploads/2020/05/Enclosure_Reference_Back.png 1020w, https://eequalspi.com/wp-content/uploads/2020/05/Enclosure_Reference_Back-300x76.png 300w, https://eequalspi.com/wp-content/uploads/2020/05/Enclosure_Reference_Back-768x194.png 768w" sizes="auto, (max-width: 504px) 85vw, 504px" /><figcaption>Rear Panel. Bent along (Faint) dotted red vertical lines, which are not visible in the final enclosure.</figcaption></figure> 651 652 653 654<p class="wp-block-paragraph"><a href="http://eequalspi.com/attachments/Nixie%20Clock%20Enclosure%20R7.svg">A raw, laser-cut friendly Inkscape SVG file can be found here</a>, with the front and back on various layers.</p> 655 656 657 658<h2 class="wp-block-heading">Conclusion</h2> 659 660 661 662<p class="wp-block-paragraph">Well folks, that’
662s the hardware in a nutshell. The software will be another post.</p> 663 </div><!-- .entry-content --> 664 665 <footer class="entry-footer"> 666 <span class="byline"><span class="author vcard"><img alt='' src='https://secure.gravatar.com/avatar/e9a139e10fb91ac23ce9e30dc5c5f06e0ebeed3ce543b00735e0a3ad11f638f8?s=49&d=mm&r=g' srcset='https://secure.gravatar.com/avatar/e9a139e10fb91ac23ce9e30dc5c5f06e0ebeed3ce543b00735e0a3ad11f638f8?s=98&d=mm&r=g 2x' class='avatar avatar-49 photo' height='49' width='49' loading='lazy' decoding='async'/><span class="screen-reader-text">Author </span> <a class="url fn n" href="https://eequalspi.com/index.php/author/thejbw/">thejbw</a></span></span><span class="posted-on"><span class="screen-reader-text">Posted on </span><a href="https://eequalspi.com/index.php/2020/05/16/uniac-hardware-in-detail/" rel="bookmark"><time class="entry-date published" datetime="2020-05-16T15:16:39-07:00">May 16, 2020</time><time class="updated" datetime="2020-05-16T15:37:11-07:00">May 16, 2020</time></a></span><span class="cat-links"><span class="screen-reader-text">Categories </span><a href="https://eequalspi.com/index.php/category/clocks/" rel="category tag">Clocks</a>, <a href="https://eequalspi.com/index.php/category/nixie/" rel="category tag">Nixie</a>, <a href="https://eequalspi.com/index.php/category/uncategorized/" rel="category tag">Uncategorized</a>, <a href="https://eequalspi.com/index.php/category/uniac/" rel="category tag">UNIAC</a></span><span class="tags-links"><span class="screen-reader-text">Tags </span><a href="https://eequalspi.com/index.php/tag/nixie/" rel="tag">Nixie</a>, <a href="https://eequalspi.com/index.php/tag/raspberrypi/" rel="tag">RaspberryPi</a>, <a href="https://eequalspi.com/index.php/tag/rpi/" rel="tag">RPi</a>, <a href="https://eequalspi.com/index.php/tag/spotify/" rel="tag">Spotify</a>, <a href="https://eequalspi.com/index.php/tag/uniac/" rel="tag">UNIAC</a></span><span class="comments-link"><a href="https://eequalspi.com/index.php/2020/05/16/uniac-hardware-in-detail/#comments">2 Comments<span class="screen-reader-text"> on UNIAC Hardware In Detail</span></a></span> </footer><!-- .entry-footer --> 667</article><!-- #post-288 --> 668 669<article id="post-277" class="post-277 post type-post status-publish format-standard hentry category-code tag-python tag-raspberrypi tag-raspotify tag-spotify tag-spotipy tag-uniac"> 670 <header class="entry-header"> 671 672 <h2 class="entry-title"><a href="https://eequalspi.com/index.php/2020/04/18/refactoring-the-uniac-playback-code/" rel="bookmark">Refactoring The UNIAC Playback Code</a></h2> </header><!-- .entry-header --> 673 674 675 676 <div class="entry-content"> 677 678<p class="wp-block-paragraph">One of the most problematic parts of the UNIAC project has been the music playback software. The original software used the Mopidy music player for command line playback. Mopidy-spotify provided Spotify connectivity to the software. The mpd python library then allowed me to control playback programmatically. </p> 679 680 681 682<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/04/image-1024x453.png" alt="" class="wp-image-281" width="531" height="234" srcset="https://eequalspi.com/wp-content/uploads/2020/04/image-1024x453.png 1024w, https://eequalspi.com/wp-content/uploads/2020/04/image-300x133.png 300w, https://eequalspi.com/wp-content/uploads/2020/04/image-768x339.png 768w, https://eequalspi.com/wp-content/uploads/2020/04/image-1536x679.png 1536w, https://eequalspi.com/wp-content/uploads/2020/04/image-2048x905.png 2048w, https://eequalspi.com/wp-content/uploads/2020/04/image-1200x530.png 1200w, http://eequalspi.com/wp-content/uploads/2020/04/image.png 3326w" sizes="auto, (max-width: 531px) 85vw, 531px" /><figcaption>Old Mopidy + MPD based flow</figcaption></figure> 683 684 685 686<p class="wp-block-paragraph">This had several problems.</p> 687 688 689 690<ol class="wp-block-list"><li>Mopidy-spotify is partially broken. Spotify themselves no longer support this interface, and haven’t since 2016. To get it working at all requires a hacked fork of Mopidy-spotify which might break forever at any time.</li><li>Response between Python and Mopidy can be really laggy and requires a continuous ping (every 30 seconds) to keep the connection alive.</li><li>Loading a new playlist in Mopidy requires significant caching and can have tens of seconds of lag, making the whole system unreasonably slow.</li></ol> 691 692 693 694<p class="wp-block-paragraph">
694This was all a legacy of the fact that I had designed the software for UNIAC in 2015 and the Mopidy workflow was the only one I could find for getting Spotify playback on a Raspberry Pi. In early 2020, after hearing about Spotifyd from <a href="https://www.dinofizzotti.com/blog/2020-02-05-diskplayer-using-3.5-floppy-disks-to-play-albums-on-spotify/">the Diskplayer project</a>, I was awoken to more modern alternatives.</p> 695 696 697 698<p class="wp-block-paragraph">After some rework, I ripped out Mopidy and mpd, and replaced it with <a href="https://github.com/dtcooper/raspotify">raspotify</a> as a player and <a href="https://spotipy.readthedocs.io/en/2.11.1/">Spotipy</a> to interface with Spotify.</p> 699 700 701 702<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/04/image-1-1024x439.png" alt="" class="wp-image-282" width="521" height="223" srcset="https://eequalspi.com/wp-content/uploads/2020/04/image-1-1024x439.png 1024w, https://eequalspi.com/wp-content/uploads/2020/04/image-1-300x128.png 300w, https://eequalspi.com/wp-content/uploads/2020/04/image-1-768x329.png 768w, https://eequalspi.com/wp-content/uploads/2020/04/image-1-1536x658.png 1536w, https://eequalspi.com/wp-content/uploads/2020/04/image-1-2048x877.png 2048w, https://eequalspi.com/wp-content/uploads/2020/04/image-1-1200x514.png 1200w, http://eequalspi.com/wp-content/uploads/2020/04/image-1.png 3302w" sizes="auto, (max-width: 521px) 85vw, 521px" /><figcaption>New Raspotify + Spotipy based flow</figcaption></figure> 703 704 705 706<p class="wp-block-paragraph">This has several advantages.</p> 707 708 709 710<ol class="wp-block-list"><li>The control API that Spotipy uses is actively supported by Spotify</li><li>Raspotify makes the Pi show up as a Spotify speaker, meaning active playback can be bounced between devices.</li><li>Spotipy is controlling my Spotify state, not Mopidy, so it can actually control playback of other devices that are actively playing music.</li><li>By the same token, pausing and unpausing on other clients (phone, laptop, etc.) works seamlessly.</li><li>Music is streamed, not buffered. This means that loading a new playlist is as instant as it is on the desktop client.</li></ol> 711 712 713 714<p class="wp-block-paragraph">All in all, this means that the switch resulted in a much more pleasant user experience. On top of that, the system is generally more stable than it was before.</p> 715 716 717 718<p class="wp-block-paragraph">Plus, setting up Raspotify was orders of magnitude less difficult than Mopidy. Raspotify managed to work automagically after apt-get installing it and setting it up as a service. This was unlike Mopidy, which took forever to point at the right sound card and get working. </p> 719 720 721 722<p class="wp-block-paragraph">There were some hiccups in figuring out how to connect to Spotify with Spotifyd, but the biggest tricks were:</p> 723 724 725 726<ol class="wp-block-list"><li>Learning that the credential saving path should be a full filename, not a path to a directory.</li><li>Realizing that the redirect URI could be “http://localhost”. To make that work, all you have to do is run the login script from the command line on your Pi and then copy the URL it feeds you to a browser on a desktop machine. Once you accept the terms, all you have to do is copy the ‘broken’ URL that it takes you to back into your Pi command line and hit enter. Things should work from there.</li></ol> 727 728 729 730<p class="wp-block-paragraph">If you’re looking to build a Raspberry Pi / Spotify player, avoid MPD and go for a Spotipy / Raspotify combo!</p> 731 732 733 734<p class="wp-block-paragraph"><a href="https://github.com/wespo/UNIAC/tree/spotifyd">The revised code can be found here.</a></p> 735 </div><!-- .entry-content --> 736 737 <footer class="entry-footer"> 738 <span class="byline"><span class="author vcard"><img alt='' src='https://secure.gravatar.com/avatar/e9a139e10fb91ac23ce9e30dc5c5f06e0ebeed3ce543b00735e0a3ad11f638f8?s=49&d=mm&r=g' srcset='https://secure.gravatar.com/avatar/e9a139e10fb91ac23ce9e30dc5c5f06e0ebeed3ce543b00735e0a3ad11f638f8?s=98&d=mm&r=g 2x' class='avatar avatar-49 photo' height='49' width='49' loading='lazy' decoding='async'/><span class="screen-reader-text">Author </span> <a class="url fn n" href="https://eequalspi.com/index.php/author/thejbw/">thejbw</a></span></span><span class="posted-on"><span class="screen-reader-text">Posted on </span><a href="https://eequalspi.com/index.php/2020/04/18/refactoring-the-uniac-playback-code/" rel="bookmark"><time class="entry-date published" datetime="2020-04-18T16:39:24-07:00">April 18, 2020</time><time class="updated" datetime="2020-04-18T16:44:45-07:00">April 18, 2020</time></a></span><span class="cat-links"><span class="screen-reader-text">Categories </span><a href="https://eequalspi.com/index.php/category/code/" rel="category tag">
738Code</a></span><span class="tags-links"><span class="screen-reader-text">Tags </span><a href="https://eequalspi.com/index.php/tag/python/" rel="tag">Python</a>, <a href="https://eequalspi.com/index.php/tag/raspberrypi/" rel="tag">RaspberryPi</a>, <a href="https://eequalspi.com/index.php/tag/raspotify/" rel="tag">Raspotify</a>, <a href="https://eequalspi.com/index.php/tag/spotify/" rel="tag">Spotify</a>, <a href="https://eequalspi.com/index.php/tag/spotipy/" rel="tag">Spotipy</a>, <a href="https://eequalspi.com/index.php/tag/uniac/" rel="tag">UNIAC</a></span> </footer><!-- .entry-footer --> 739</article><!-- #post-277 --> 740 741<article id="post-273" class="post-273 post type-post status-publish format-standard hentry category-code tag-python tag-spotify tag-spotipy"> 742 <header class="entry-header"> 743 744 <h2 class="entry-title"><a href="https://eequalspi.com/index.php/2020/04/11/spotipyd-configuration/" rel="bookmark">Spotipy-configuration</a></h2> </header><!-- .entry-header --> 745 746 747 748 <div class="entry-content"> 749 750<p class="wp-block-paragraph">If you are trying to set up <a href="https://spotipy.readthedocs.io/en/2.11.1/">Spotipy</a>, like me, and you want to cache your credentials but are getting the following error, </p> 751 752 753 754<pre class="wp-block-preformatted">warning:couldn't write token cache to /home/pi/spotipy_credentials</pre> 755 756 757 758<p class="wp-block-paragraph">and have to auth on every run, it’s likely because in your call to</p> 759 760 761 762<pre class="wp-block-preformatted">spotipy.Spotify(client_credentials_manager=SpotifyOAuth(...)</pre> 763 764 765 766<p class="wp-block-paragraph">you specified cache_path as something like:</p> 767 768 769 770<pre class="wp-block-preformatted">cache_path='/home/pi/spotipy_credentials/'</pre> 771 772 773 774<p class="wp-block-paragraph">Because, naturally, that’s a path. In fact, cache_path is a full file path (i.e. it contains a writable filename). I did this instead:</p> 775 776 777 778<pre class="wp-block-preformatted">cache_path='/home/pi/spotipy_credentials/.cache-' + username,</pre> 779 780 781 782<p class="wp-block-paragraph">where username was a variable I wrote. As far as I know, you could just write make the filename ‘credentials.txt’ if you wanted…</p> 783 784 785 786<p class="wp-block-paragraph">Anyway, hope that helps someone else.</p> 787 </div><!-- .entry-content --> 788 789 <footer class="entry-footer"> 790 <span class="byline"><span class="author vcard"><img alt='' src='https://secure.gravatar.com/avatar/e9a139e10fb91ac23ce9e30dc5c5f06e0ebeed3ce543b00735e0a3ad11f638f8?s=49&d=mm&r=g' srcset='https://secure.gravatar.com/avatar/e9a139e10fb91ac23ce9e30dc5c5f06e0ebeed3ce543b00735e0a3ad11f638f8?s=98&d=mm&r=g 2x' class='avatar avatar-49 photo' height='49' width='49' loading='lazy' decoding='async'/><span class="screen-reader-text">Author </span> <a class="url fn n" href="https://eequalspi.com/index.php/author/thejbw/">thejbw</a></span></span><span class="posted-on"><span class="screen-reader-text">Posted on </span><a href="https://eequalspi.com/index.php/2020/04/11/spotipyd-configuration/" rel="bookmark"><time class="entry-date published" datetime="2020-04-11T17:05:50-07:00">April 11, 2020</time><time class="updated" datetime="2020-04-18T13:46:52-07:00">April 18, 2020</time></a></span><span class="cat-links"><span class="screen-reader-text">Categories </span><a href="https://eequalspi.com/index.php/category/code/" rel="category tag">Code</a></span><span class="tags-links"><span class="screen-reader-text">Tags </span><a href="https://eequalspi.com/index.php/tag/python/" rel="tag">Python</a>, <a href="https://eequalspi.com/index.php/tag/spotify/" rel="tag">Spotify</a>, <a href="https://eequalspi.com/index.php/tag/spotipy/" rel="tag">Spotipy</a></span> </footer><!-- .entry-footer --> 791</article><!-- #post-273 --> 792 793<article id="post-219" class="post-219 post type-post status-publish format-standard hentry category-clocks category-nixie category-uniac tag-nixie tag-python tag-spotify tag-uniac"> 794 <header class="entry-header"> 795 796 <h2 class="entry-title"><a href="https://eequalspi.com/index.php/2020/04/04/uniac-the-ultimate-nixie-internet-alarm-clock/" rel="bookmark">UNIAC: The Ultimate Nixie Internet Alarm Clock.</a></h2> </header><!-- .entry-header --> 797 798 799 800 <div class="entry-content"> 801 802<figure class="wp-block-image size-large"><img loading="lazy" decoding="async" width="640" height="479" src="http://eequalspi.com/w
802p-content/uploads/2020/01/IMG_5816.gif" alt="" class="wp-image-234"/><figcaption>UNIAC. The non-portable 2015 UNIAC prototype is lurking in the background…waiting.</figcaption></figure> 803 804 805 806<h2 class="wp-block-heading">Introduction</h2> 807 808 809 810<p class="wp-block-paragraph">What is UNIAC? It is the <strong>U</strong>ltimate <strong>N</strong>ixie <strong>I</strong>nternet <strong>A</strong>larm <strong>C</strong>lock. <br>It’s a Nixie alarm clock / boombox.</p> 811 812 813 814<ul class="wp-block-list"><li>It uses a Raspberry Pi to stream music from Spotify. </li><li>It has integral IN-13 VU meters to visualize the music. </li><li>It’s got a robot voice to relay information that the Nixies cannot. </li><li>It’s got clickety light-up buttons on the front. </li><li>It’s got a translucent clamshell case made of smoked acrylic.</li></ul> 815 816 817 818<p class="wp-block-paragraph">It’s a piece of the future that never was. In short, it’s <em>cool</em>. </p> 819 820 821 822<h2 class="wp-block-heading">Motivation and Background</h2> 823 824 825 826<div class="wp-block-image"><figure class="alignright size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/01/IMG_0403.jpg" alt="" class="wp-image-217" width="248" height="186" srcset="https://eequalspi.com/wp-content/uploads/2020/01/IMG_0403.jpg 800w, https://eequalspi.com/wp-content/uploads/2020/01/IMG_0403-300x225.jpg 300w, https://eequalspi.com/wp-content/uploads/2020/01/IMG_0403-768x576.jpg 768w" sizes="auto, (max-width: 248px) 85vw, 248px" /><figcaption>My First Nixie Display</figcaption></figure></div> 827 828 829 830<p class="wp-block-paragraph">I built my first Nixie Clock in 2006, which worked, but I was never satisfied with the design. I soon began fantasizing about what my dream Nixie clock would look like. It would replace my dusty old RadioShack alarm clock. </p> 831 832 833 834<p class="wp-block-paragraph">Unfortunately, life got in the way. The project got shelved, and grad school came along, but the idea hung in the back of my mind. By 2015, the technology landscape had changed and my hands on electronics skills had grown. I had new options, and came up with a new plan using a RaspberryPi. The ultimate Nixie clock would have:</p> 835 836 837 838<div class="wp-block-image"><figure class="alignright is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2019/07/Screen-Shot-2019-07-09-at-10.29.47-PM.png" alt="" class="wp-image-172" width="267" height="142" srcset="https://eequalspi.com/wp-content/uploads/2019/07/Screen-Shot-2019-07-09-at-10.29.47-PM.png 876w, https://eequalspi.com/wp-content/uploads/2019/07/Screen-Shot-2019-07-09-at-10.29.47-PM-300x159.png 300w, https://eequalspi.com/wp-content/uploads/2019/07/Screen-Shot-2019-07-09-at-10.29.47-PM-768x407.png 768w" sizes="auto, (max-width: 267px) 85vw, 267px" /><figcaption>The cheap LED alarm clock that motivated me.</figcaption></figure></div> 839 840 841 842<ul class="wp-block-list"><li>Clock</li><li>Alarm</li><li>Calendar</li><li>Spotify as the music/alarm source</li></ul> 843 844 845 846<p class="wp-block-paragraph">To tackle this relatively complex project, I decided to break it into parts. After tackling each subsystem individually, I had a reliable, tested circuit and was able then to integrate them into a unified system.</p> 847 848 849 850<h2 class="wp-block-heading">Two Builds</h2> 851 852 853 854<p class="wp-block-paragraph">The first version was built in late 2015. It was a cube of laser cut acrylic sheets with the various subsystems mounted to an internal backplane with standoffs. The internal structure was built from square 3/8″ dowels which held the sides together. This version has served well on my electronics bench since it was put together, but it always bothered me that it was extremely cumbersome to open up and service. Additionally, the acrylic backplane was just inelegant.</p> 855 856 857 858<div class="wp-block-group"><div class="wp-block-group__inner-container is-layout-flow wp-block-group-is-layout-flow"> 859<figure class="wp-block-image is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/w
859p-content/uploads/2020/03/IMG_1337-1024x575.jpg" alt="" class="wp-image-247" width="565" height="317" srcset="https://eequalspi.com/wp-content/uploads/2020/03/IMG_1337-1024x575.jpg 1024w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_1337-300x169.jpg 300w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_1337-768x432.jpg 768w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_1337-1536x863.jpg 1536w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_1337-2048x1151.jpg 2048w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_1337-1200x674.jpg 1200w, http://eequalspi.com/wp-content/uploads/2020/03/IMG_1337-scaled.jpg 2560w" sizes="auto, (max-width: 565px) 85vw, 565px" /><figcaption>UNIAC 2015: Front view</figcaption></figure> 860 861 862 863<figure class="wp-block-image is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/03/IMG_1339-1024x575.jpg" alt="" class="wp-image-248" width="564" height="317" srcset="https://eequalspi.com/wp-content/uploads/2020/03/IMG_1339-1024x575.jpg 1024w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_1339-300x169.jpg 300w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_1339-768x432.jpg 768w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_1339-1536x863.jpg 1536w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_1339-2048x1151.jpg 2048w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_1339-1200x674.jpg 1200w, http://eequalspi.com/wp-content/uploads/2020/03/IMG_1339-scaled.jpg 2560w" sizes="auto, (max-width: 564px) 85vw, 564px" /><figcaption>UNIAC 2015: Rear view. I never got around to fabricating the back panel.</figcaption></figure> 864 865 866 867<figure class="wp-block-image is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/03/IMG_1342-1024x575.jpg" alt="" class="wp-image-250" width="558" height="313" srcset="https://eequalspi.com/wp-content/uploads/2020/03/IMG_1342-1024x575.jpg 1024w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_1342-300x169.jpg 300w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_1342-768x432.jpg 768w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_1342-1536x863.jpg 1536w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_1342-2048x1151.jpg 2048w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_1342-1200x674.jpg 1200w, http://eequalspi.com/wp-content/uploads/2020/03/IMG_1342-scaled.jpg 2560w" sizes="auto, (max-width: 558px) 85vw, 558px" /><figcaption>UNIAC 2015: Top view with the lid off. Inside can be seen the backplane and the rails it slides into.</figcaption></figure> 868</div></div> 869 870 871 872<p class="wp-block-paragraph">In 2019, with this in mind I decided I could do better. I integrated all of the components (except the front panel buttons and speakers) onto a motherboard. With a single board, I decided on a boombox form factor. This version isn’t really a good fit for a bedside alarm clock, but it is extremely satisfying.</p> 873 874 875 876<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/03/IMG_5285-1024x768.png" alt="" class="wp-image-252" width="597" height="448" srcset="https://eequalspi.com/wp-content/uploads/2020/03/IMG_5285-1024x768.png 1024w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5285-300x225.png 300w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5285-768x576.png 768w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5285-1200x900.png 1200w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5285.png 1280w" sizes="auto, (max-width: 597px) 85vw, 597px" /><figcaption>UNIAC 2019, in the boombox style clamshell case.</figcaption></figure> 877 878 879 880<p class="wp-block-paragraph">To enable this, I built an acrylic bending jig, and designed a clamshell case to hold it all. The case was made from two pieces of laser cut acrylic. The back panel is solid black to keep ambient light out. The front is smoked grey and hides the electronics but lets the Nixie goodness shine through. </p> 881 882 883 884<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/w
884p-content/uploads/2020/03/IMG_5038-768x1024.png" alt="" class="wp-image-254" width="594" height="792" srcset="https://eequalspi.com/wp-content/uploads/2020/03/IMG_5038-768x1024.png 768w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5038-225x300.png 225w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5038-1152x1536.png 1152w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5038-1536x2048.png 1536w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5038-1200x1600.png 1200w, http://eequalspi.com/wp-content/uploads/2020/03/IMG_5038.png 3024w" sizes="auto, (max-width: 594px) 85vw, 594px" /><figcaption>Acrylic bender on the bench with a piece of test plastic (and the rev of UNIAC 2019 mobo in the background).</figcaption></figure> 885 886 887 888<p class="wp-block-paragraph">Getting the acrylic bent at the right spot took a few tries — the first test (using cheaper clear plastic) put the bend too close to the button cutouts. This caused the holes to deform and become teardrop shaped. I still think the clear case has a cool 90’s feel to it, but that doesn’t fit my general design tastes, so I stuck with the plan to go to a smoked front panel.</p> 889 890 891 892<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/03/IMG_5040-1024x768.png" alt="" class="wp-image-255" width="598" height="449" srcset="https://eequalspi.com/wp-content/uploads/2020/03/IMG_5040-1024x768.png 1024w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5040-300x225.png 300w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5040-768x576.png 768w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5040-1536x1152.png 1536w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5040-2048x1536.png 2048w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5040-1200x900.png 1200w, http://eequalspi.com/wp-content/uploads/2020/03/IMG_5040.png 4032w" sizes="auto, (max-width: 598px) 85vw, 598px" /><figcaption>UNIAC 2019: First test enclosure.</figcaption></figure> 893 894 895 896<p class="wp-block-paragraph">After a couple of revisions, the final two piece enclosure came together nicely. I was worried that lifting the unit by the handle would cause the acrylic to flex, but it’s actually reasonably sturdy. I might consider some additional brackets to more firmly attack the front to the back in the future. For now, I think mounting the two haves together through motherboard standoffs is sufficient.</p> 897 898 899 900<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/03/IMG_5287-1024x768.png" alt="" class="wp-image-253" width="599" height="449" srcset="https://eequalspi.com/wp-content/uploads/2020/03/IMG_5287-1024x768.png 1024w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5287-300x225.png 300w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5287-768x576.png 768w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5287-1200x900.png 1200w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5287.png 1280w" sizes="auto, (max-width: 599px) 85vw, 599px" /><figcaption><br>UNIAC 2019 showing the clamshell case open, with the motherboard and button board.</figcaption></figure> 901 902 903 904<h2 class="wp-block-heading">The VU-Meter</h2> 905 906 907 908<div class="wp-block-image"><figure class="alignright size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2017/02/vumeter1.png" alt="" class="wp-image-18" width="355" height="125" srcset="https://eequalspi.com/wp-content/uploads/2017/02/vumeter1.png 898w, https://eequalspi.com/wp-content/uploads/2017/02/vumeter1-300x106.png 300w, https://eequalspi.com/wp-content/uploads/2017/02/vumeter1-768x270.png 768w" sizes="auto, (max-width: 355px) 85vw, 355px" /><figcaption>The IN-13 Vu-Meter as a standalone module.</figcaption></figure></div> 909 910 911 912<p class="wp-block-paragraph">When audio is playing from UNIAC, it really needed to show some “activity” — something like an oscilloscope would work, but in keeping with the Nixie theme, I decided to use the IN-13 bargraph tubes to display the sound levels on the left and right channels. No digital trickery here, the module takes analog line-level audio as a passthrough and displays the amplitude level of the audio channels on its IN-13 bargraph tubes. I’ve seen lots of mono IN-13 VU-meters, and I’ve seen a few standalone modules, but I’
912ve never seen them combined with normal Nixies before. </p> 913 914 915 916<p class="wp-block-paragraph">While I originally designed the VU-meter module intending to use it as a drop in component in UNIAC, the circuit has seen more service hours as a standalone module in my hi-fi (it’s been in near-constant use since late 2015). Nonetheless, it looks great in its intended role as a component of UNIAC.</p> 917 918 919 920<p class="wp-block-paragraph">I described the design of this component in detail <a href="http://eequalspi.com/index.php/2017/02/13/in-13-stereo-vu-meter/">in a series of previous posts</a>, which includes some theory, design decisions, and schematics. </p> 921 922 923 924<h2 class="wp-block-heading">The Nixie Display</h2> 925 926 927 928<p class="wp-block-paragraph">Because UNIAC is a media player, it needed a general purpose addressable Nixie display, not just a Nixie clock module. This part of the project was actually the first I began to tackle, back in 2009. I had nearly finished a display module using an 8051 and written in assembly, but stopped work when I went back to school. With cross-fading and all sorts of neat features, it was more or less what I wanted, but it had minor ghosting issues that I was unwilling to tolerate. Therefore, version one (2015) used <a href="https://www.shop-tes.com/smartnixie/display-module/">Smart Nixie modules from Taylor Edge</a> with a modified backplane. </p> 929 930 931 932<div class="wp-block-image"><figure class="alignright size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/03/low-res-Apple-Devices-SD.gif" alt="" class="wp-image-261" width="229" height="134"/><figcaption>Nixie display using a Teensy 3.2 developed for another project.</figcaption></figure></div> 933 934 935 936<p class="wp-block-paragraph">For the final version (2019), I based the design off a four tube Nixie display module using a Teensy 3.2 I had built for another project. When I finish that project, I will describe it in detail in a post. Until then, you can see the prototype at the right. The chief advantages to this design are a reduction in cost versus six Smart Nixie sockets, and the ability to integrate it onto the new motherboard without using risers. The UNIAC version of the display supports six tubes and uses IN12As, but is otherwise broadly the same design. </p> 937 938 939 940<p class="wp-block-paragraph">Input is via USB serial, TTL serial or i2c inputs and supports both dimming and crossfading.</p> 941 942 943 944<p class="wp-block-paragraph">Admittedly, multiplexing by 6x instead of 4x leads to a slightly dimmer display than the previous Smart Nixie approach, but it’s good enough. If there’s a future build, I’ll likely split it up into two banks of three tubes to increase the brightness (at the cost of board area and complexity).</p> 945 946 947 948<h2 class="wp-block-heading">The Motherboard</h2> 949 950 951 952<p class="wp-block-paragraph">With the Nixie display circuit and the vu-meter circuit validated, it was time to build a full system. </p> 953 954 955 956<p class="wp-block-paragraph">Version 1, built in 2015 prototype was a ‘wired together modules’ build. Using a laser cut backplane, the various modules were mounted to both sides with standoffs. The backplane then slotted into a cube made with an internal wooden frame covered with laser cut panels. This design worked well, but the rats nest of wires made it an absolute nightmare to open up and work on. </p> 957 958 959 960<p class="wp-block-paragraph">For the final version, I decided I had to replace the backplane board with a PCB. The new motherboard would have an integrated copy of the Nixie display and vu-meter circuitry. A footprint The Raspberry Pi, audio DAC, and amplifier would be on board as well. It would take 12V in, and the only off board connections would be the speakers and to the front panel buttons. Because all my peripherals used serial interfaces, the actual board design was actually pretty sparse, and most of the work was in routing the traces for the Nixie display in a way that maintained sufficient creepage.</p> 961 962 963 964<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/w
964p-content/uploads/2020/03/IMG_5286-1024x768.png" alt="" class="wp-image-257" width="599" height="449" srcset="https://eequalspi.com/wp-content/uploads/2020/03/IMG_5286-1024x768.png 1024w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5286-300x225.png 300w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5286-768x576.png 768w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5286-1200x900.png 1200w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5286.png 1280w" sizes="auto, (max-width: 599px) 85vw, 599px" /><figcaption>UNIAC 2019 motherboard front view.</figcaption></figure> 965 966 967 968<p class="wp-block-paragraph">Taking a look at the front side of the motherboard (above), it’s primarily the cosmetic components. We see the six IN-12A tubes, eight INS-1 neon bulbs, two IN-13 tubes. Also of note are the unpopulated pads along the bottom for connecting the buttons directly to the RaspberryPi, which are unused in this build in favor of the i2c button board (described in the next section).</p> 969 970 971 972<h2 class="wp-block-heading">A Tour of the Motherboard</h2> 973 974 975 976<p class="wp-block-paragraph">On the back side of the board, we can see a ton of components. </p> 977 978 979 980<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" src="http://eequalspi.com/wp-content/uploads/2020/03/IMG_5289-1024x768.png" alt="" class="wp-image-256" width="599" height="449" srcset="https://eequalspi.com/wp-content/uploads/2020/03/IMG_5289-1024x768.png 1024w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5289-300x225.png 300w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5289-768x576.png 768w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5289-1200x900.png 1200w, https://eequalspi.com/wp-content/uploads/2020/03/IMG_5289.png 1280w" sizes="auto, (max-width: 599px) 85vw, 599px" /><figcaption>UNIAC 2019: Motherboard back view.</figcaption></figure> 981 982 983 984<p class="wp-block-paragraph">Next, in green with a raspberry symbol, is the main CPU, a RaspberryPi Zero W (hereafter RPi), which is the core of the system.</p> 985 986 987 988<p class="wp-block-paragraph">To the right of that is a rainbow ribbon cable going off to the button board.</p> 989 990 991 992<p class="wp-block-paragraph">Next, at the right is a TES-1364H boost module. This provides HV for the IN-13s. It is twinned with another -1364 at the top right, which provides HV for the numbers. I chose to keep the two supplies separate not because I was sure I was out of current, but because the two sets of tubes call for different striking voltages, and I didn’t feel like adjusting the values of the two display circuits to compensate. In a future revision, I’ll absolutely address that.</p> 993 994 995 996<p class="wp-block-paragraph">The group of components just right of center are the components for the IN-13 display, which are described in more detail in the IN-13 VUMeter posts, but the two DIP ICs are a quad op-amp and an ATTINY85. </p> 997 998 999 1000<p class="wp-block-paragraph">The two tiny green three-pin boards are <a href="https://power.murata.com/pub/data/power/oki-78sr.pdf">Mu-rata OKI-78SR</a> modules. These are more efficient drop in replacements for the classic LM7805. </p> 1001 1002 1003 1004<p class="wp-block-paragraph">Directly above the RPi is a purple board. <a href="http://eequalspi.com/index.php/2019/08/25/mopidy-and-multiple-audio-streams-from-the-command-line-on-raspberry-pi/">This is the i2s sound card using the PCM5102A ic</a>.</p> 1005 1006 1007 1008<p class="wp-block-paragraph">Connected to the sound card is a blue <a href="https://www.adafruit.com/product/1752">Adafruit class-d amplifier board</a> at the bottom left. It was chosen because it is relatively low-noise, has a mute pin, and can use an external pot for volume control — here you can see the wire for the pot running off to the knob on the side of the rear panel.</p> 1009 1010 1011 1012<p class="wp-block-paragraph">Finally at the top left is a <a href="https://www.pjrc.com/teensy/index.html">Teensy 3.2</a>, the CPU for the Nixie display module. This is gross overkill to drive a display, but it was convenient to code up quickly, and I was able to set it up as an i2c slave, simplifying communication with the RPi.</p> 1013 1014 1015 1016<h2 class="wp-block-heading">The Button Board</h2> 1017 1018 1019 1020<div class="wp-block-image"><figure class="alignright is-resized"><img loading="lazy" decoding="async" src="https://i.ebayimg.com/images/g/2KsAAOSwjwpc1GDi/s-l1600.jpg" alt="https://i.ebayimg.com/images/g/2KsAAOSwjwpc1GDi/s-l1600.jpg" width="240" height="159"/><figcaption>Clicky momentary 12V buttons, sourced from eBay</figcaption></figure></div> 1021 1022 1023 1024<p class="wp-block-paragraph">For the control panel interface I chose some clicky 12V illuminated momentary buttons that were intended for industrial applications. Very satisfying. They were about $1.30 per each, so not cheap, however. Given that the buttons are the main user interface, having something that satisfies the retro vibe satisfactorily was worth it.</p> 1025 1026 1027 1028<p class="wp-block-paragraph">The 2015 version used a single GPIO pin on the raspberry pi for each button, and used a single GPIO (through a FET, obviously) to
1028switch the lighting on them all on together. This, again, led to a tedious amount of manual wiring, so I designed a button board using a MCP23017 GPIO expander to connect to the buttons. The board itself is very simple, although I had the first boards manufactured by AllPCB, and they failed to route the slots, despite saying they’d confirm the slots with checkplots in an email discussion beforehand. This triggered my switch to PCBWay who correctly provided checkplots and produced the right board. I have been using them since, and who have treated me well — no they aren’t sponsoring me, I’m just pissed off enough at AllPCB to mention it, since they ignored my customer complaint that I filed after the fact.</p> 1029 1030 1031 1032<h2 class="wp-block-heading">The Battery Problem</h2> 1033 1034 1035 1036<p class="wp-block-paragraph">Okay, it’s time for full disclosure, I’ve been calling this project portable, but throughout the build process I treated a battery as “something I would figure out later” — It turns out the BMSs are no joke, and there wasn’t much out there that would suit my needs. The fundamental problem is that there’s a large burst of current on power up, despite the fact that the overall system only draws a few hundred mA when fully up and running. I tried a few low cost boost converters and they all browned out before the system booted. As I wanted to share the portable UNIAC with my friends at PAX 2019, I ended up punting last minute and <a href="https://www.amazon.com/gp/product/B00ME3ZH7C/">taping a 12V battery pack from Amazon</a> to the back of the unit.</p> 1037 1038 1039 1040<h2 class="wp-block-heading">Music Playback</h2> 1041 1042 1043 1044<p class="wp-block-paragraph">To play music, I am using the command line media player Mopidy and its Spotify plugin, Mopidy-Spotify. This requires a premium Spotify account to work, and is brittle. The API Mopidy-Spotify uses is not supported anymore. I’ve found that the repo fails to load my playlists unless I use the fork mentioned in <a href="https://github.com/BlackLight/mopidy-spotify/tree/fix/incompatible_playlists">this thread</a>. </p> 1045 1046 1047 1048<p class="wp-block-paragraph">Getting the audio itself to work was also a massive pain, as the various Linux audio subsystems like to fight as is, and the I2S audio card I was using made things more difficult. I could go into more detail here, but I think it merits its own post…</p> 1049 1050 1051 1052<p class="wp-block-paragraph"><a href="http://eequalspi.com/index.php/2019/08/25/mopidy-and-multiple-audio-streams-from-the-command-line-on-raspberry-pi/">So I wrote a full post about it!</a></p> 1053 1054 1055 1056<h2 class="wp-block-heading">Display Library</h2> 1057 1058 1059 1060<p class="wp-block-paragraph">For the first version of the UNIAC with TES SmartNixie modules, I whipped up a quick python library to interface with them. It might come in handy for someone else, so I have <a href="https://github.com/wespo/SmartNixie">published it here</a>.</p> 1061 1062 1063 1064<p class="wp-block-paragraph">For the final version, I was using my own i2c display module, so I wrote a (nearly) drop-in replacement library for the SmartNixie library, so I could minimally modify the main UNIAC application to support the new display. It is <a href="https://github.com/wespo/NixieDisplay">published here</a>.</p> 1065 1066 1067 1068<p class="wp-block-paragraph">It supports some fun features like dimming, cross-fading, blanking, and blinking.</p> 1069 1070 1071 1072<h2 class="wp-block-heading">The UNIAC Application</h2> 1073 1074 1075 1076<p class="wp-block-paragraph">The main UNIAC application is a python script. The main loop probes the interface buttons and then calls a python god object, which maintains various states, drives the displays and voice, and sends audio commands to Mopidy. There’s a lot to this application, but that’s an entire post in and of itself. Until I get around to a full writeup for it, you can find it <a href="https://github.com/wespo/UNIAC">published here.</a></p> 1077 1078 1079 1080<h2 class="wp-block-heading">Conclusion</h2> 1081 1082 1083 1084<p class="wp-block-paragraph">At the end of the project, UNIAC is probably the most satisfying hobby project I have yet made. Due to the brittle nature of the Mopidy-spotify, my next task is to move the Spotify interface to spotifyd, which I discovered due to reading <a href="https://www.dinofizzotti.com/blog/2020-02-05-diskplayer-using-3.5-floppy-disks-to-play-albums-on-spotify/">Dino Fizotti’s excellent Diskplayer writeup.</a> The other glaringly obvious improvement is adding a proper, internal battery system.</p> 1085 1086 1087 1088<p class="wp-block-paragraph">Longer term, I’d like to try to integrate it with a voice assistant to really supercharge interface, but that is more software work than I’m willing to take on in the immediate future.</p> 1089 1090 1091 1092<p class="wp-block-paragraph">The sad irony however, is that I’ve spent so long listening to the crappy buzzer of my Radio Shack alarm clock that I actually don’t want to give it up now. I’m conditioned to wake up to it quickly, and it takes up little space on my nightstand. Oh well. Maybe the next project will be a UNIAC Mini with an alarm buzzer feature.</p> 1093 1094 1095 1096<p class="wp-block-paragraph">I know this has been a long post. Thanks for sticking with me! </p> 1097 1098 1099 1100<p class="wp-block-paragraph">o/</p> 1101 </div><!-- .entry-content --> 1102 1103 <footer class="entry-footer"> 1104 <span class="byline"><span class="author vcard"><img alt='' src='https://secure.gravatar.com/avatar/e9a139e10fb91ac23ce9e30dc5c5f06e0ebeed3ce543b00735e0a3ad11f638f8?s=49&d=mm&r=g' srcset='https://secure.gravatar.com/avatar/e9a139e10fb91ac23ce9e30dc5c5f06e0ebeed3ce543b00735e0a3ad11f638f8?s=98&d=mm&r=g 2x' class='avatar avatar-49 photo' height='49' width='49' loading='lazy' decoding='async'/><span class="screen-reader-text">Author </span> <a class="url fn n" href="https://eequalspi.com/index.php/author/thejbw/">thejbw</a></span></span><span class="posted-on"><span class="screen-reader-text">Posted on </span><a href="https://eequalspi.com/index.php/2020/04/04/uniac-the-ultimate-nixie-internet-alarm-clock/" rel="bookmark"><time class="entry-date published" datetime="2020-04-04T17:47:30-07:00">April 4, 2020</time><time class="updated" datetime="2020-04-18T13:48:35-07:00">April 18, 2020</time></a></span><span class="cat-links"><span class="screen-reader-text">Categories </span><a href="https://eequalspi.com/index.php/category/clocks/" rel="category tag">Clocks</a>, <a href="https://eequalspi.com/index.php/category/nixie/" rel="category tag">Nixie</a>, <a href="https://eequalspi.com/index.php/category/uniac/" rel="category tag">UNIAC</a></span><span class="tags-links"><span class="screen-reader-text">Tags </span><a href="https://eequalspi.com/index.php/tag/nixie/" rel="tag">Nixie</a>, <a href="https://eequalspi.com/index.php/tag/python/" rel="tag">Python</a>, <a href="https://eequalspi.com/index.php/tag/spotify/" rel="tag">Spotify</a>, <a href="https://eequalspi.com/index.php/tag/uniac/" rel="tag">UNIAC</a></span><span class="comments-link"><a href="https://eequalspi.com/index.php/2020/04/04/uniac-the-ultimate-nixie-internet-alarm-clock/#comments">5 Comments<span class="screen-reader-text"> on UNIAC: The Ultimate Nixie Internet Alarm Clock.</span></a></span> </footer><!-- .entry-footer --> 1105</article><!-- #post-219 --> 1106 1107<article id="post-171" class="post-171 post type-post status-publish format-standard hentry category-uncategorized"> 1108 <header class="entry-header"> 1109 1110 <h2 class="entry-title"><a href="https://eequalspi.com/index.php/2020/01/01/displaying-mw-with-nixies/" rel="bookmark">Displaying MW with Nixies</a></h2> </header><!-- .entry-header --> 1111 1112 1113 1114 <div class="entry-content"> 1115 1116<p class="wp-block-paragraph">My fascination with <a href="https://en.wikipedia.org/wiki/Nixie_tube">Nixie tubes</a> began around 2006. These beautiful retro tubes make amazing displays and have been made into hundreds of well documented clocks. At that time I bought a handful of tubes and got permission to build a Nixie clock as project for a senior level undergrad EE lab course. I actually built it as two separate boards, a serially addressed Nixie display and a serial output clock module. </p> 1117 1118 1119 1120<p class="wp-block-paragraph">Both the display and the clock were built around an AT89C4051 microcontroller, with direct drive using one <a href="https://tubehobby.com/show_det.php?det=34">K155ID1</a> per chip. The high voltage supply was a switch mode module from <a href="https://www.ledsales.com.au/index.php?main_page=product_info&cPath=197_199&products_id=652&zenid=2jj8c25680l798b77uhaeo2920">LEDSales</a> (I have since moved on and all my more recent projects use the <a href="https://www.tayloredge.com/storefront/SmartNixie/DataSheets/Datasheet_1363-1364.pdf">Taylor Edge 1364</a>). The tubes themselves were Burroughs <a href="http://www.oddmix.com/tubes/b5750.html">B5750s</a>, which I got on pre-made break out cards with edge connectors, two tubes to a card.</p> 1121 1122 1123 1124<p class="wp-block-paragraph">The clock module also used an AT89C4051. The very simple timekeeping circuit took an AC input through a voltage divider and zener clamp and counted pulses. This is actually a surprisingly stable way of keeping time, as at least in the US, electric utilities will actually slow down or speed up frequency slightly overnight to make up for irregularities during the day. This means that while line frequency clocks are worse than cheap quartz clocks hour to hour, they are actually generally more accurate month-to-month.</p> 1125 1126 1127<p><br> 1128<!--StartFragment--></p> 1129 1130 1131<figure class="wp-block-image size-large"><img loading="lazy" decoding="async" width="1024" height="841" src="http://eequalspi.com/w
1131p-content/uploads/2020/01/EHiFqD7-1024x841.png" alt="" class="wp-image-224" srcset="https://eequalspi.com/wp-content/uploads/2020/01/EHiFqD7-1024x841.png 1024w, https://eequalspi.com/wp-content/uploads/2020/01/EHiFqD7-300x246.png 300w, https://eequalspi.com/wp-content/uploads/2020/01/EHiFqD7-768x631.png 768w, https://eequalspi.com/wp-content/uploads/2020/01/EHiFqD7-1200x986.png 1200w, https://eequalspi.com/wp-content/uploads/2020/01/EHiFqD7.png 1248w" sizes="auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px" /><figcaption>Clock PCB Schematic</figcaption></figure> 1132 1133 1134 1135<p class="wp-block-paragraph">For the display board, I didn’t have a saved copy of the routed PCB, and as it was one of the first boards I ever laid out, it wouldn’t have been good anyway, so I just re-downloaded PCB123 (again, I was a ‘young player’ as Dave Jones would say) and ran the autorouter to give you the just of the board. Each 40-pin header drove a dual Nixie card (god, the inefficiency!)</p> 1136 1137 1138 1139<figure class="wp-block-image size-large"><img loading="lazy" decoding="async" width="1024" height="624" src="http://eequalspi.com/wp-content/uploads/2020/01/s9Uf6kO-1024x624.png" alt="" class="wp-image-225" srcset="https://eequalspi.com/wp-content/uploads/2020/01/s9Uf6kO-1024x624.png 1024w, https://eequalspi.com/wp-content/uploads/2020/01/s9Uf6kO-300x183.png 300w, https://eequalspi.com/wp-content/uploads/2020/01/s9Uf6kO-768x468.png 768w, https://eequalspi.com/wp-content/uploads/2020/01/s9Uf6kO.png 1118w" sizes="auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px" /><figcaption>Nixie display board, takes serial input via DB-9 and displays the data on six nixies and 8 NE2 neons. </figcaption></figure> 1140 1141 1142 1143<p class="wp-block-paragraph">I was never really happy with the clock design, from a user perspective, so it got put away pretty quickly. The display module, on the other hand was really satisfying. It ended up at my first full time job. Because I worked at the local power company, and had access to real-time <a href="https://en.wikipedia.org/wiki/SCADA">SCADA</a> data for the grid, it was used to display the power consumption of the city we were in (in MW).</p> 1144 1145 1146 1147<figure class="wp-block-image size-large"><img loading="lazy" decoding="async" width="800" height="600" src="http://eequalspi.com/wp-content/uploads/2020/01/IMG_0403.jpg" alt="" class="wp-image-217" srcset="https://eequalspi.com/wp-content/uploads/2020/01/IMG_0403.jpg 800w, https://eequalspi.com/wp-content/uploads/2020/01/IMG_0403-300x225.jpg 300w, https://eequalspi.com/wp-content/uploads/2020/01/IMG_0403-768x576.jpg 768w" sizes="auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 984px) 61vw, (max-width: 1362px) 45vw, 600px" /><figcaption>My first ever Nixie display, showing 1294.87 MW of power consumption.</figcaption></figure> 1148 1149 1150 1151<p class="wp-block-paragraph">The code ran in Python and used a command line utility to extract the various datapoints, which it then drove to the display, updating every five seconds or so. The final version would rotate between showing power consumption for two cities that we served, and the temperature (ËF) in each of those places.</p> 1152 1153 1154 1155<figure class="wp-block-image size-large"><img loading="lazy" decoding="async" width="800" height="556" src="http://eequalspi.com/wp-content/uploads/2020/01/IMG_0401.jpg" alt="" class="wp-image-222" srcset="https://eequalspi.com/wp-content/uploads/2020/01/IMG_0401.jpg 800w, https://eequalspi.com/wp-content/uploads/2020/01/IMG_0401-300x209.jpg 300w, https://eequalspi.com/wp-content/uploads/2020/01/IMG_0401-768x534.jpg 768w" sizes="auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 984px) 61vw, (max-width: 1362px) 45vw, 600px" /><figcaption>Temperature in degrees Farenheit.</figcaption></figure> 1156 1157 1158 1159<p class="wp-block-paragraph">It definitely got a few looks over the years that I had it running, and I still have the display in a box somewhere, but I’ve moved on career wise, so I don’t have the cool data to display in real time anymore.</p> 1160 1161 1162 1163<p class="wp-block-paragraph">Oh well, not much of a story, but I thought I might as well document it and share.</p> 1164 </div><!-- .entry-content --> 1165 1166 <footer class="entry-footer"> 1167 <span class="byline"><span class="author vcard"><img alt='' src='https://secure.gravatar.com/avatar/e9a139e10fb91ac23ce9e30dc5c5f06e0ebeed3ce543b00735e0a3ad11f638f8?s=49&d=mm&r=g' srcset='https://secure.gravatar.com/avatar/e9a139e10fb91ac23ce9e30dc5c5f06e0ebeed3ce543b00735e0a3ad11f638f8?s=98&d=mm&r=g 2x' class='avatar avatar-49 photo' height='49' width='49' loading='lazy' decoding='async'/><span class="screen-reader-text">Author </span> <a class="url fn n" href="https://eequalspi.com/index.php/author/thejbw/">thejbw</a></span></span><span class="posted-on"><span class="screen-reader-text">Posted on </span><a href="https://eequalspi.com/index.php/2020/01/01/displaying-mw-with-nixies/" rel="bookmark"><time class="entry-date published" datetime="2020-01-01T20:17:51-08:00">January 1, 2020</time><time class="updated" datetime="2020-01-01T20:18:44-08:00">January 1, 2020</time></a></span><span class="cat-links"><span class="screen-reader-text">Categories </span><a href="https://eequalspi.com/index.php/category/uncategorized/" rel="category tag">Uncategorized</a></span> </footer><!-- .entry-footer --> 1168</article><!-- #post-171 --> 1169 1170<article id="post-203" class="post-203 post type-post status-publish format-standard hentry category-holiday category-low-power"> 1171 <header class="entry-header"> 1172 1173 <h2 class="entry-title"><a href="https://eequalspi.com/index.php/2019/12/30/christmas-ornaments-2019/" rel="bookmark">
1173Christmas Ornaments 2019</a></h2> </header><!-- .entry-header --> 1174 1175 1176 1177 <div class="entry-content"> 1178 1179<figure class="wp-block-video"><video controls src="http://eequalspi.com/wp-content/uploads/2019/12/7eOpldF.mp4"></video><figcaption>The Las Vegas Christmas Ornament</figcaption></figure> 1180 1181 1182 1183<h2 class="wp-block-heading">Background</h2> 1184 1185 1186 1187<p class="wp-block-paragraph">Every year I like to do some sort of artistic project as a gift. Historically they have been unique one-offs that I have yet to post here. This year however, I decided to do something a little more traditional — a Christmas ornament. I figured I could ‘mass produce’ them, and give one to everyone relevant, including sending them along with my annual holiday cards.</p> 1188 1189 1190 1191<p class="wp-block-paragraph">Given that I hail from Vegas, I decided that the way to go was to do a Christmas version of the famous <a href="https://en.wikipedia.org/wiki/Welcome_to_Fabulous_Las_Vegas_sign">‘Welcome to Fabulous Las Vegas Nevada’</a> sign.</p> 1192 1193 1194 1195<div class="wp-block-image"><figure class="aligncenter size-large"><img loading="lazy" decoding="async" width="946" height="720" src="http://eequalspi.com/wp-content/uploads/2019/12/946px-Welcome_to_Fabulous_Las_Vegas.jpg" alt="" class="wp-image-205" srcset="https://eequalspi.com/wp-content/uploads/2019/12/946px-Welcome_to_Fabulous_Las_Vegas.jpg 946w, https://eequalspi.com/wp-content/uploads/2019/12/946px-Welcome_to_Fabulous_Las_Vegas-300x228.jpg 300w, https://eequalspi.com/wp-content/uploads/2019/12/946px-Welcome_to_Fabulous_Las_Vegas-768x585.jpg 768w" sizes="auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px" /><figcaption>Image Credit: <a href="https://en.wikipedia.org/wiki/Welcome_to_Fabulous_Las_Vegas_sign#/media/File:Welcome_to_Fabulous_Las_Vegas.jpg">Wikipedia</a></figcaption></figure></div> 1196 1197 1198 1199<h2 class="wp-block-heading">Circuit Design</h2> 1200 1201 1202 1203<p class="wp-block-paragraph">The first challenge was coming up with a circuit. My primary requirement was that it should be able to last a whole season on a single coin cell (CR2032). Obviously, even with high efficiency LEDs, that would be nigh impossible, and giving up and going to 2AAs would have made the board too heavy to realistically hang on a tree.</p> 1204 1205 1206 1207<p class="wp-block-paragraph">I therefore decided that it would start to blink when triggered by a human somehow and would then shut off after a few seconds. I briefly considered using a <a href="https://learn.adafruit.com/pir-passive-infrared-proximity-motion-sensor/overview">passive infrared (PIR) motion sensor</a>, which would have been affordable from the usual Chinese suspects on ebay, and would have met my power requirements (they can be incredibly low power in standby) but they also are rather bulky compared to size and weight requirements of an ornament. </p> 1208 1209 1210 1211<p class="wp-block-paragraph">The second (and obvious fallback option) would be a simple <a href="https://www.google.com/search?q=tactile+switch&client=firefox-b-1-d&sxsrf=ACYBGNQnINCEOLCeF1kIBAzsZJIX618pjg:1577321061364&source=lnms&tbm=isch&sa=X&ved=2ahUKEwigtLzsitLmAhVSMH0KHUIyDTAQ_AUoAnoECBAQBA&biw=1680&bih=953&dpr=2">tactile switch</a>. This has several advantages:</p> 1212 1213 1214 1215<ul class="wp-block-list"><li>Cheap</li><li>Easy to implement</li><li>Low parts count</li></ul> 1216 1217 1218 1219<p class="wp-block-paragraph">Unfortunately, it has one fundamental flaw: To activate it requires a non-trivial amount of force. Not exactly a problem for most devices, but for an ornament dangling from a tree, it wouldn’t do, to require the user to grab and hold it (possibly with two hands) to make it do something. This left one more option: Touch switch.</p> 1220 1221 1222 1223<p class="wp-block-paragraph">The design is extremely simple — since I can afford to expose bare copper (well, tinned), I can float the base of a transistor to act as a switch when a touch to the exposed metal pulls the input to VCC </p> 1224 1225 1226 1227<div class="wp-block-image"><figure class="aligncenter size-large"><img loading="lazy" decoding="async" width="1024" height="617" src="http://eequalspi.com/w
1227p-content/uploads/2019/12/Screen-Shot-2019-12-30-at-5.37.25-PM-1024x617.png" alt="" class="wp-image-207" srcset="https://eequalspi.com/wp-content/uploads/2019/12/Screen-Shot-2019-12-30-at-5.37.25-PM-1024x617.png 1024w, https://eequalspi.com/wp-content/uploads/2019/12/Screen-Shot-2019-12-30-at-5.37.25-PM-300x181.png 300w, https://eequalspi.com/wp-content/uploads/2019/12/Screen-Shot-2019-12-30-at-5.37.25-PM-768x463.png 768w, https://eequalspi.com/wp-content/uploads/2019/12/Screen-Shot-2019-12-30-at-5.37.25-PM-1536x926.png 1536w, https://eequalspi.com/wp-content/uploads/2019/12/Screen-Shot-2019-12-30-at-5.37.25-PM-1200x723.png 1200w, https://eequalspi.com/wp-content/uploads/2019/12/Screen-Shot-2019-12-30-at-5.37.25-PM.png 1550w" sizes="auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px" /><figcaption>Darlington touch switch. Touch output is taken from the low side of the 3.3MΩ pull up.</figcaption></figure></div> 1228 1229 1230 1231<p class="wp-block-paragraph">For the metal plates, I designed a pair on interdigitated polygons, as below, with one side pulled to VCC and the other connected to the base of the transistor.</p> 1232 1233 1234 1235<div class="wp-block-image"><figure class="aligncenter"><img decoding="async" src="https://i.imgur.com/w7kiH1P.png" alt="https://i.imgur.com/w7kiH1P.png"/><figcaption>Touch area physical layout.</figcaption></figure></div> 1236 1237 1238 1239<p class="wp-block-paragraph">Note that this design would not work with even the thinnest of gloves, is prone to corrosion, and might not even work for someone with extremely dry skin. BUT, it is cheap, simple, and extremely low power â wasting less than 1 µA quiescent current.</p> 1240 1241 1242 1243<p class="wp-block-paragraph">For the main circuit, I started out with an all analog design. The touch switch would have triggered a mono-stable oscillator, which turned on a bi-stable block, which in turn would drive the LEDs through a buffer transistor. There were several problems with this approach however.</p> 1244 1245 1246 1247<ul class="wp-block-list"><li>A jellybean 556 cannot run down to 2V (the dropout voltage for my single lithium cell) reliably.</li><li>More sophisticated timer ICs are similarly priced (or more expensive) than a microcontroller.</li><li>The standby current would at least as high as what I could achieve with a microcontroller in deep sleep.</li></ul> 1248 1249 1250 1251<p class="wp-block-paragraph">Since I already had the tool chain set up to develop with the ATTINY85 microcontroller, I chose it â if I had more time to develop, I would likely have spun up the ATTINY10 (and indeed, I grabbed a handful of them) since they’re so low cost.</p> 1252 1253 1254 1255<p class="wp-block-paragraph"> I chose run the ATTINY on its internal 1MHz oscillator, for absolute minimum power consumption. I also chose a <a href="https://www.digikey.com/product-detail/en/microchip-technology/ATTINY85V-10SH/ATTINY85V-10SH-ND/2238296">variant</a> which could run down to 1.8V, which would let me run my single CR2032 pretty much dry.</p> 1256 1257 1258 1259<p class="wp-block-paragraph">The final design, shown below was criminally simple. I tested it on a breadboard while I developed code and was able to drop it onto the PCB with (essentially) no changes.</p> 1260 1261 1262 1263<div class="wp-block-image"><figure class="aligncenter"><img decoding="async" src="https://i.imgur.com/MVX2LAk.png" alt="https://i.imgur.com/MVX2LAk.png"/><figcaption>The resulting design. Twelve red LEDs, ten green LEDs, a micro and a pair of NPNs. The battery holder makes an appearance at top left.</figcaption></figure></div> 1264 1265 1266 1267<p class="wp-block-paragraph">I decided I was going for so low parts count that I even chose to omit the decoupling cap on the micro â I figured since it was the only active component, I could get away with saving the penny.</p> 1268 1269 1270 1271<p class="wp-block-paragraph">The biggest omission, however, was using only a single current limiting resistor for each color of LEDs. This is obviously bad practice and you should never, ever do this (TM), but given that my power supply is a high ESR lithium battery and the LEDs were grouped from a single batch on each board, I decided to take the risk. The reason for this is simple, it saved me 22 resistors and realistically, needing to find a way to handle a double sided load in the hobby reflow oven (or more realistically, soldering down by hand 4x as many components as I already was planning to, per board).</p> 1272 1273 1274 1275<h2 class="wp-block-heading">Code</h2> 1276 1277 1278 1279<p class="wp-block-paragraph">Writing code for the ATTINY85 is almost criminally easy given that it is supported by the Arduino environment. Programming can be done with my trusty <a href="https://www.sparkfun.com/products/11801">Sparkfun TinyAVR programmer</a>, which I used with an <a href="https://www.ebay.com/itm/SOIC8-SOP8-Flash-Chip-IC-Test-Clips-Socket-Adpter-BIOS-24-25-93-Programmer-MS/383036575885">SOIC adapter clip</a> to program the SOIC parts I used in-circuit.</p> 1280 1281 1282 1283<p class="wp-block-paragraph">The underlying code is, unsurprisingly simple, but I am pleased with the design. After boot, the system goes to deep sleep (SLEEP_MODE_PWR_DOWN) until awoken by an external GPIO interrupt. When triggered, turns on one phase of the LEDs (e.g. red), goes back to sleep, after setting the watchdog timer, which awakens it a half-ish second later. On wake, it toggles to the alternate LED phase (to green or back to red), and repeats until the requisite number of cycles has been completed. Then it goes back to deep sleep.</p> 1284 1285 1286 1287<figure class="wp-block-image size-large"><img loading="lazy" decoding="async" width="1024" height="347" src="http://eequalspi.com/w
1287p-content/uploads/2019/12/Code-Block-Diagram-1024x347.png" alt="" class="wp-image-210" srcset="https://eequalspi.com/wp-content/uploads/2019/12/Code-Block-Diagram-1024x347.png 1024w, https://eequalspi.com/wp-content/uploads/2019/12/Code-Block-Diagram-300x102.png 300w, https://eequalspi.com/wp-content/uploads/2019/12/Code-Block-Diagram-768x261.png 768w, https://eequalspi.com/wp-content/uploads/2019/12/Code-Block-Diagram-1536x521.png 1536w, https://eequalspi.com/wp-content/uploads/2019/12/Code-Block-Diagram-1200x407.png 1200w, https://eequalspi.com/wp-content/uploads/2019/12/Code-Block-Diagram.png 1804w" sizes="auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px" /><figcaption>Block diagram of LED Flasher code</figcaption></figure> 1288 1289 1290 1291<p class="wp-block-paragraph">The code can be found on GitHub <a href="https://github.com/wespo/ATTINY85_Ornament">here</a>.</p> 1292 1293 1294 1295<h2 class="wp-block-heading">Layout</h2> 1296 1297 1298 1299<p class="wp-block-paragraph">The layout is fairly straightforward. I laid out the board outline and silkscreen in inkscape, and then following various tutorials imported the outline and silkscreen into Eagle. Sizing the two correctly was a guess-and check experience. I didn’t take comprehensive notes on my import process, so unless someone asks for it, or I do it again next year, I’ll leave the details out of this post.</p> 1300 1301 1302 1303<p class="wp-block-paragraph">I am somewhat proud of removing all but a handful of visible vias and one trace on top of the board by hiding most of the vias underneath the LEDs.</p> 1304 1305 1306 1307<div class="wp-block-image"><figure class="aligncenter is-resized"><img loading="lazy" decoding="async" src="https://i.imgur.com/AbbmUH5.png" alt="https://i.imgur.com/AbbmUH5.png" width="600" height="537"/><figcaption>Final layout</figcaption></figure></div> 1308 1309 1310 1311<h2 class="wp-block-heading">Conclusion</h2> 1312 1313 1314 1315<p class="wp-block-paragraph">I did take some measurements, and the device draws about 5mA while blinking and about 2µA when off (Not that much worse than the self discharge rate of the CR2032), so I’d call the design a roaring success. It certainly was a hit at the holidays! </p> 1316 1317 1318 1319<p class="wp-block-paragraph">This was a fun, quick and dirty Christmas ornament project and I will be revisiting it in the future. Expect a 2020 Christmas project post.</p> 1320 </div><!-- .entry-content --> 1321 1322 <footer class="entry-footer"> 1323 <span class="byline"><span class="author vcard"><img alt='' src='https://secure.gravatar.com/avatar/e9a139e10fb91ac23ce9e30dc5c5f06e0ebeed3ce543b00735e0a3ad11f638f8?s=49&d=mm&r=g' srcset='https://secure.gravatar.com/avatar/e9a139e10fb91ac23ce9e30dc5c5f06e0ebeed3ce543b00735e0a3ad11f638f8?s=98&d=mm&r=g 2x' class='avatar avatar-49 photo' height='49' width='49' loading='lazy' decoding='async'/><span class="screen-reader-text">Author </span> <a class="url fn n" href="https://eequalspi.com/index.php/author/thejbw/">thejbw</a></span></span><span class="posted-on"><span class="screen-reader-text">Posted on </span><a href="https://eequalspi.com/index.php/2019/12/30/christmas-ornaments-2019/" rel="bookmark"><time class="entry-date published" datetime="2019-12-30T20:37:15-08:00">December 30, 2019</time><time class="updated" datetime="2020-01-01T15:06:27-08:00">January 1, 2020</time></a></span><span class="cat-links"><span class="screen-reader-text">Categories </span><a href="https://eequalspi.com/index.php/category/holiday/" rel="category tag">Holiday</a>, <a href="https://eequalspi.com/index.php/category/low-power/" rel="category tag">Low Power</a></span> </footer><!-- .entry-footer --> 1324</article><!-- #post-203 --> 1325 1326 <nav class="navigation pagination" aria-label="Posts pagination"> 1327 <h2 class="screen-reader-text">Posts pagination</h2> 1328 <div class="nav-links"><span aria-current="page" class="page-numbers current"><span class="meta-nav screen-reader-text">Page </span>1</span> 1329<a class="page-numbers" href="https://eequalspi.com/index.php/page/2/"><span class="meta-nav screen-reader-text">Page </span>2</a> 1330<a class="page-numbers" href="https://eequalspi.com/index.php/page/3/"><span class="meta-nav screen-reader-text">Page </span>3</a> 1331<a class="next page-numbers" href="https://eequalspi.com/index.php/page/2/">Next page</a></div> 1332 </nav>
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