Photo frame built on an ESP32 with an E-Paper display. The picture shown in the frame can be changed from a smartphone over a WiFi web interface

Detailed explaination on my website.

For this project, I used only existing modules from Waveshare and some spare parts from my drawers.

• 7.5inch E-Paper (B) E-Ink from Waveshare
  • black/white/red colors
  • 480x800px resolution
• Universal e-Paper Raw Panel Driver Board from Waveshare too
  • ESP32 MCU from Espressif
  • 4MB ROM & 512kB RAM
  • WiFi and BLE capabilities
  • 3.3v or 5v power
  • E-Paper driving circuit included
• 3x AA battery handler
  • Provides 4.5v, enough to make it work
• Any 13x18cm photo frame you like

All the MCU software is written in C, based on the excellent ESP-IDF. To avoid all the IDF installation, I used a devcontainer on VSCode, thanks to this guy! On the Web side, I used the standard trio HTML5/CSS3/JavaSript.

The image taken from a camera is very different from the one an E-Paper display needs. My display needs a 480×800 pixels frame, with colors encoded on 2 bits (black/white and red/non-red). As the input image can be very large, it’s difficult to send it entirely to the ESP32 to process it. Then I decided to process the image in the browser, with some Javascript code.

First the image is rotated to landscape format if it’s higher than larger. The script crops it to a 5:3 ratio as on the display then downsizes it to a width of 800 pixels. Now that the image has the right size, the last step is to convert it to our very reduced colorspace. To do so, I used the Floyd-Steinberg dithering algorithm after the quantization process to have a nice result.

© BDeliers - 2023
Under Apache-2 License