E-ink digital photo frame

prusaprinters

<p>This is a small wifi powered photo frame that runs on battery (for a long time). For showing the photos, it uses a three color (black, white, red) 2.13" e-ink display with a resolution of 104x212 pixels.<br><br>The e-ink display only need power when updating the photo, which mean that the photo frame is running in deep sleep most of the time. It works as follows:<br>&nbsp;</p><ol><li>Wakes up every 3.1 hours, or when touching a small hidden touch pin on the side of the frame (can be seen in one of the photos).</li><li>Enables WiFi and connects to a local server that hosts the photo to show.</li><li>Downloads the photo (two bitmaps, one with the pixels that should be drawn with black, and one with pixels that should be drawn in red).</li><li>Draw the image (first black, then red).</li><li>Go back to deep sleep.<br>&nbsp;</li></ol><p>This is how a drawing looks like. Updating the display is quite slow which is a characteristics of the e-ink/ePaper display. You can see that it first draw black followed by red. This is in real time:&nbsp;</p><figure class="image"><img src="https://media.prusaprinters.org/media/prints/146942/rich_content/1a6116d2-f4f6-4583-8fdd-14828595471f/ezgifcom-gif-maker-5.gif#%7B%22uuid%22%3A%22c4488ffa-e5ac-4645-a9a1-bb76638e04ef%22%2C%22w%22%3A320%2C%22h%22%3A333%7D"></figure><p>Design wise, there is not much happening. The box is sized to fit the <a href="https://www.banggood.com/1_54-Inch-or-2_13-Inch-or-2_9-Inch-Flexible-Ink-Screen-LCD-Module-E-paper-Electronic-Paper-Display-Compatible-with-Arduino-or-STM32-or-Raspberry-p-1811238.html?utm_design=18&amp;utm_email=1630990225_2324&amp;utm_source=emarsys&amp;utm_medium=Shipoutinform190813&amp;utm_campaign=trigger-logistics&amp;utm_content=leander&amp;sc_src=email_2671705&amp;sc_eh=ecc7de549363680f1&amp;sc_llid=31297336&amp;sc_lid=104858042&amp;sc_uid=mXarTVDCqm&amp;cur_warehouse=CN&amp;ID=62904186302659">2.13" e-ink</a>, a LiPo 3.7V 3000mAh battery, the <a href="https://www.wemos.cc/en/latest/s2/s2_mini.html">ESP-32-S2 mini</a> and a <a href="https://www.pololu.com/product/2560">DC-DC step up converter</a>.</p><p>Server side, there is a bunch of stuff happening.<br>Parodically (a couple of times a month), a index of all my Google Photo are downloaded. Not the photos themselves, but just the index. When the photo frame is requesting a photo (using http), in short this is what is happening:</p><ol><li>A random photo is picked from the index, and downloaded.</li><li>The downloaded photo is resized and the colors are remapped to white, black and red (using that palette).</li><li>Then two different bitmaps are extracted, one for only the black pixels, and one for only the red ones. Step 2 and 3 are using <a href="https://imagemagick.org/index.php">imagemagick</a>.</li><li>Each bitmap is then converted into bitmap format that the <a href="https://github.com/ZinggJM/GxEPD">e-ink library</a> understands.</li><li>These are then packaged in one payload that the esp-32 receives.</li><li>The esp-32 draws each bitmap, first black then red, and then go back to sleep.</li></ol><p>&nbsp;</p><p>I will upload all the source code! There are a bunch of different things and scripts going on to make all of this work. I need to document and format them a bit first, so stay tuned.</p>