This project is based on my #reDOT project. Basically it is a 5x7 SMD LED Matrix an a microcontroller on one PCB. I started with 0201 LEDs (see first project log), but this was not reliable. So a two other Versions with 0402 followed. 0402 LEDs do have some benefits over 0201:
- bigger and you can solder them better
- more colors availible
The microcontroller (a low coast STM8) drives all LEDs directly with multiplexing. For controlling a i2c interface is available. On the back is a male pinheader which fits the SAO-standard.
The PCB needed to be 4 Layers to get this dense Parts population.