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Allow for WS2812 PWM to work on DMAMUX-capable devices #9471

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Jul 16, 2020
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Allow for WS2812 PWM to work on DMAMUX-capable devices #9471

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3 changes: 2 additions & 1 deletion docs/ws2812_driver.md
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Original file line number Diff line number Diff line change
Expand Up @@ -92,6 +92,7 @@ Configure the hardware via your config.h:
#define WS2812_PWM_PAL_MODE 2 // Pin "alternate function", see the respective datasheet for the appropriate values for your MCU. default: 2
#define WS2812_DMA_STREAM STM32_DMA1_STREAM2 // DMA Stream for TIMx_UP, see the respective reference manual for the appropriate values for your MCU.
#define WS2812_DMA_CHANNEL 2 // DMA Channel for TIMx_UP, see the respective reference manual for the appropriate values for your MCU.
#define WS2812_DMAMUX_ID STM32_DMAMUX1_TIM2_UP // DMAMUX configuration for TIMx_UP -- only required if your MCU has a DMAMUX peripheral, see the respective reference manual for the appropriate values for your MCU.
```

You must also turn on the PWM feature in your halconf.h and mcuconf.h
Expand All @@ -117,5 +118,5 @@ Note: This only applies to STM32 boards.

To configure the `RGB_DI_PIN` to open drain configuration add this to your config.h file:
```c
#define WS2812_EXTERNAL_PULLUP
#define WS2812_EXTERNAL_PULLUP
```
8 changes: 8 additions & 0 deletions drivers/chibios/ws2812_pwm.c
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Expand Up @@ -23,6 +23,9 @@
#ifndef WS2812_DMA_CHANNEL
# define WS2812_DMA_CHANNEL 2 // DMA Channel for TIMx_UP
#endif
#if (STM32_DMA_SUPPORTS_DMAMUX == TRUE) && !defined(WS2812_DMAMUX_ID)
# error "please consult your MCU's datasheet and specify in your config.h: #define WS2812_DMAMUX_ID STM32_DMAMUX1_TIM?_UP"
#endif

// Push Pull or Open Drain Configuration
// Default Push Pull
Expand Down Expand Up @@ -184,6 +187,11 @@ void ws2812_init(void) {
dmaStreamSetMode(WS2812_DMA_STREAM, STM32_DMA_CR_CHSEL(WS2812_DMA_CHANNEL) | STM32_DMA_CR_DIR_M2P | STM32_DMA_CR_PSIZE_WORD | STM32_DMA_CR_MSIZE_WORD | STM32_DMA_CR_MINC | STM32_DMA_CR_CIRC | STM32_DMA_CR_PL(3));
// M2P: Memory 2 Periph; PL: Priority Level

#if (STM32_DMA_SUPPORTS_DMAMUX == TRUE)
// If the MCU has a DMAMUX we need to assign the correct resource
dmaSetRequestSource(WS2812_DMA_STREAM, WS2812_DMAMUX_ID);
#endif

// Start DMA
dmaStreamEnable(WS2812_DMA_STREAM);

Expand Down