Etlas: e-paper display for news, stocks, and the weather

ETLAS: E-PAPER DISPLAY FOR NEWS, STOCKS, AND THE WEATHER

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05 SEPTEMBER 2024

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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.

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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.

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The following diagram outlines this system architecture.

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architecture

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Unlike my e-reader, which worked with raster images, +Etlas downloads time series data as CSV and computes the price curves on the +ESP32.

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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.

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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.

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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.

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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.

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Files: source.tar.gz

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by W. D. Sadeep Madurange

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.

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.

Unlike my e-reader, which worked with raster images, -Etlas downloads time series data as CSV and computes the price curves on the -ESP32.

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.

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.

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.

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.