This project is based on my #reDOT
project. Basicly it is a 5x7 SMD LED Matrix an a microcontroller on one PCB. I started wirh 0201 LEDs (see first project log), but this was not reliable. So a second version with 0402 is in development. 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 UART interface is available. The dimensions are like a DIP-6 package. For easy connection of multiple PCBs, the pads are castellated. Also the supply rails are available on both sides. So multiple of these display can be soldered together to a bigger display without the need of additional wiring.
This is planed as chainable. Therefore connected pins for the supply rails are available on both sides. The idea is to solder them together like I did with #tiny7. The RX pin of the second display would be connected to the TX pin of the first one (the most left one). So the firmware must implement some kind of UART-shiftregister to control all displays with same firmware
MASTER DISPLAY #1 DISPLAY #2 +-----------------+ +--------+ +--------+ | UART-USB |---+5V--->|VCC--VCC|---+5V--->|VCC--VCC| | or other TX|----->----|RX TX|--------->|RX TX|-> | microcontroller |---GND--->|GND--GND|---GND--->|GND GND| +-----------------+ +--------+ +--------+ unneeded data flowing out at the end of the chain
Project is not yet ready. For prototyping specially for the software #reDOT and a cheap chinese development board with a STM8 will be used (see also there for a early version of the firmware)