Display an image onto e-paper. This repo expects a server to hold images that are sized to the paper and reports Last-Modified headers (as refreshes take a long time with 3-color paper). For a sample server, see https://github.com/sweeneyb/epaper-images.

The use-case is infrequently updating messages to passers-by, info tags for art, QR displays, etc. Once this works, I'll give the paper+esp32 pair a GUID, and pull images from the server by GUID to individually address them. This bypasses any difficulty in text/font rendering that the adafruit libraries address. Links to a test server to come later.

Hardware

https://www.aliexpress.us/item/3256805623572150.html The board I ordered seems to have been displaced by a cheaper option. https://www.aliexpress.us/item/2251832767050812.html. I can't attest that I've verified that board, though. https://www.aliexpress.us/item/3256804935498922.html

Image gen

Use golang's image tools, then a bit of custom processing to get into something like an xbm. It's really a bit-field (as XBM is a text format that embeds into C code). The greyscaling could also probably be better.

Mentions

https://github.com/lagunax/ESP32-upng - For a while, I wanted to decode on the embedded system. Turns out, I didn't have enough memory for 2 images. But I appreciate this library being available.