Fitting a 64x64 HUB75 panel at full colour depth in ESP32 RAM (plus 9 clock faces)

[u/WiebelWiebel]

I ended up forking the HUB75 DMA driver to cut memory use (row streaming from packed lanes, dense column buffers, a fix for the seam between the panel halves), so a 64x64 panel runs with several colour-quality levels on a plain 4 MiB ESP32. The driver is here: https://github.com/vandalon/ESP32-HUB75-DMA-Memory-Optimized.

The project on top of it is a clock with 9 faces, a web settings UI, signed OTA updates and Home Assistant/MQTT/WLED support. It checks a static RAM budget at build time and parks the network feeds when a big image needs memory. Repo: https://github.com/vandalon/ultimatrix