bitbanging WS2812's with the CH32v203

[ReFil]

I'm trying to get the WS2812 on the Adafruit QT PY CH32V203 board working, but i cannot get the timings right. Looking at the delay code any sub 1us delay gets rounded up to 1us (

ch32-hal/src/delay/impl_qingke_v2_v4.rs

Line 65 in 4fde792

let us = ns / 1000 + if ns % 1000 == 0 { 0 } else { 1 };

) , which would explain why i'm having all sorts of gremlins making it actually work. Is this a known bug? Is there a reason that sub 1us delay is not permissible?

[holly-hacker]

A bit late, but if you have the SPI peripheral available you can (ab)use that. I did something similar in the past (also on a CH32V203) which you can find here: https://github.com/holly-hacker/RTN-Badge-2026NL/blob/main/src/hardware/ws2812b.rs

Hopefully the comments are are self-explanatory on why the specific timing was chosen.

[ReFil]

Yeah, I needed the spi peripheral to drive an spi device on this project so unfortunately I couldn't steal it for the LED.

[sysprogdev]

Consider one of these approaches to drive WS2812, SK6812 or SK6805

• DMA + PWM
• DMA + SPI (Note: bigger chips have a second SPI peripheral)
• DMA + USART
• DMA + GPIO PIN
• Alternative chip with PIOC; V205, X033, X035,

[ReFil]

I've already fixed the delays so they can be bit banged normally #224