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| author | Sadeep Madurange <sadeep@asciimx.com> | 2025-10-25 16:23:39 +0800 |
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| committer | Sadeep Madurange <sadeep@asciimx.com> | 2025-10-25 16:23:39 +0800 |
| commit | c00ff9a3b56b6aa28367488f62afcc6f8185a91f (patch) | |
| tree | f4176d823dbe0a45cb817364f27eab938f6f85cc /_site/projects/etlas/index.html | |
| parent | 18aa7dd1057cd29cc087c4f45566394692f2f01d (diff) | |
| download | www-c00ff9a3b56b6aa28367488f62afcc6f8185a91f.tar.gz | |
Render rest of the project write ups.
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diff --git a/_site/projects/etlas/index.html b/_site/projects/etlas/index.html new file mode 100644 index 0000000..ebcc018 --- /dev/null +++ b/_site/projects/etlas/index.html @@ -0,0 +1,100 @@ +<!DOCTYPE html> +<html> + <head> + <meta charset="utf-8"> + <title>Etlas: e-paper display for news, stocks, and the weather</title> + <head> +<meta charset="utf-8"> + <title>Etlas: e-paper display for news, stocks, and the weather</title> + <link rel="stylesheet" href="/assets/css/main.css"> + <link rel="stylesheet" href="/assets/css/normalize.css"> + <link rel="stylesheet" href="/assets/css/skeleton.css"> +</head> + + + </head> + <body> + + <div class="container"> + <ul id="navlist" class="left"> + <li > + <a href="/">hme</a> + </li> + <li > + <a href="/projects/">tnk</a> + </li> + <li > + <a href="/about/">abt</a> + </li> + <li><a href="/feed.xml">rss</a></li> + </ul> +</div> + + + + <main> + <div class="container"> + <h2 class="brand center" id="title">ETLAS: E-PAPER DISPLAY FOR NEWS, STOCKS, AND THE WEATHER</h2> + + <h6 class="center">05 SEPTEMBER 2024</h5> + + <br> + + <div class="threecol justify"><p>Etlas is a news, stock market, and weather tracker powered by an ESP32 NodeMCU +D1, featuring a 7.5-inch Waveshare e-paper display and a DHT22 sensor module.</p> + +<table style="border: none;"> + <tr style="border: none;"> + <td style="border: none;"><img src="dash.jpg" alt="front" style="width: 100%" /></td> + <td style="border: none;"><img src="pcb.jpg" alt="back" style="width: 100%" /></td> + </tr> +</table> + +<p>The top left panel displays the end-of-day stock prices from the Polygon.io API, relayed through my own +FastCGI-wrapped Flask app hosted on a VPS. The stock symbols can be configured +through the Flask app’s application settings. The server.fcgi script enclosed +in the tarball at the end of the page contains the Flask app.</p> + +<p>The following diagram outlines this system architecture.</p> + +<p><img src="etlas_arch.png" alt="architecture" /></p> + +<p>Unlike my <a href="/projects/e-reader">e-reader</a>, which worked with raster images, +Etlas downloads time series data as CSV and computes the price curves on the +ESP32.</p> + +<p>The more prominent panel on the right of the e-paper display shows local +(Singapore) and world news from the Channel News Asia RSS feed. The MCU +downloads and parses XML data from the RSS feed directly before rendering it to +the display. Although I did it this way to avoid writing server code, it limits +the feeds from which Etlas can receive data. In a future version, I will relay +the RSS feed through a server (like the stock prices) to make it more flexible.</p> + +<p>The bottom panels (middle and right) display the temperature and relative +humidity from a DHT22 sensor. The DHT22 driver, arguably the most interesting +part of the software, reads real-time sensor data by comparing relative pulse +widths. The pulses themselves are too quick for the ESP32 to reliably measure +directly. I ported this +implementation for ESP8266 modules to my ESP32. All credit for the algorithm +belongs to them.</p> + +<p>Much of the heavy lifting of acquiring, interpreting, and rendering data from +different data sources is performed on the microcontroller using less than 512 +KB of memory. The embedded software that makes that possible is written in C +using the ESP-IDF v5.2.1. My e-paper display driver is a port of Waveshare examples for Arduino +and STM32 platforms.</p> + +<p>I’ve been using Etlas daily (for a couple of hours on weekdays and all day on +weekends) since August 2024. As of October 2025, it’s been running reliably for +over a year. If you are interested in an e-paper display like this, drop me an +email at the address on my home page.</p> + +<p>Files: <a href="source.tar.gz">source.tar.gz</a></p> +</div> + + <p class="right italics">by W. D. Sadeep Madurange</p> + </div> + </main> + + </body> +</html> |