47 SPI LED Matrix Driver
47 : SPI LED Matrix Driver
- Author: Daniel Theunissen
- Description: SPI device that drives a matrix (or strip) of WS2812B LEDs
- GitHub repository
- Open in 3D viewer
- Clock: 12000000 Hz
How it works
This project drives a WS2812B RGB LED matrix (or strip) using the SPI protocol. Each 3 byte SPI frame gets displayed on each sequential LED in the matrix. This allows for animations to be displayed given the color composition of each pixel on each frame. For an 8x8 matrix, the expected refresh rate is roughly 300hz.
The simple write-only SPI peripheral is designed for a CPHA (clock phase) and CPOL (clock polarity) of 0 and a baudrate of 1Mhz. Each frame should consist of pulling CS low, writing 3 bytes, and pulling CS high.
After a pixel's worth of data has been recieved into the SPI register, it is latched and the LED driver is signalled to start sending data.
How to test
Connect Wires:
-
Set up outputs:
- Connect
uo[0]to the input pin (DIN) of a WS2812B LED matrix - Optionally connect
uo[1]anduo[2]to status LEDs for debugging purposes
- Connect
-
Set up the SPI connection:
- Connect
SCKtoui[0] - Connect
SDI(orMOSI) toui[1] - Connect
CStoui[2]
- Connect
Display Data:
An example micropython script can be found here
Set up a SPI peripheral with CPHA = CPOL = 0 and a baudrate of 1Mhz. Send 3 bytes of data in GRB format. The correct color should show up on the first LED in the matrix.
External hardware
- WS2812B RGB LED matrix or strip
- Up to 64 LEDs have been tested, more may or may not work
- Some SPI master device
- Tested using a Pi Pico
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | SCK | DIN | |
| 1 | SDI | LED1 | |
| 2 | CS | LED2 | |
| 3 | |||
| 4 | |||
| 5 | |||
| 6 | |||
| 7 |