WS2812B SPI DMA example

Single-file-header for SPI-DMA to output WS2812B LEDs. By chunking the outputs using the center-interrupt, it is possible to double-buffer the WS2812B output data while only storing a few LEDs worth of data in memory at once.

This outputs the LED data on the MOSI (PC6) pin of the CH32V003.

Additionally, this demo only uses 6% CPU while it's outputting LEDs and free while not and it doesn't require precise interrupt timing, increasing or decreasing DMALEDS will adjust how lineant the timing is on LED catpures.

The timing on the SPI bus is not terribly variable, the best I was able to find was:

• Ton0 = 324ns
• Ton1 = 990ns
• Toff0 = 990ns
• Toff1 = 324ns
• Treset = 68us

Usage

If you are including this in main, simply

#define WS2812DMA_IMPLEMENTATION
#include "ws2812b_dma_spi_led_driver.h"

You will need to implement the following two functions, as callbacks from the ISR.

uint32_t CallbackWS2812BLED( int ledno );

You willalso need to call

InitWS2812DMA();

Then, whenyou want to update the LEDs, call:

WS2812BStart( int num_leds );

If you want to see if it's done sending, examine WS2812BLEDInUse.