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Add support for complementary outputs to the WS2812 PWM driver #11988

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Mar 3, 2021
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3 changes: 3 additions & 0 deletions docs/ws2812_driver.md
Original file line number Diff line number Diff line change
Expand Up @@ -102,11 +102,14 @@ Configure the hardware via your config.h:
#define WS2812_PWM_DRIVER PWMD2 // default: PWMD2
#define WS2812_PWM_CHANNEL 2 // default: 2
#define WS2812_PWM_PAL_MODE 2 // Pin "alternate function", see the respective datasheet for the appropriate values for your MCU. default: 2
//#define WS2812_PWM_COMPLEMENTARY_OUTPUT // Define for a complementary timer output (TIMx_CHyN); omit for a normal timer output (TIMx_CHy).
#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.
```

Note that using a complementary timer output (TIMx_CHyN) is possible only for advanced-control timers (TIM1, TIM8, TIM20 on STM32), and the `STM32_PWM_USE_ADVANCED` option in mcuconf.h must be set to `TRUE`. Complementary outputs of general-purpose timers are not supported due to ChibiOS limitations.

You must also turn on the PWM feature in your halconf.h and mcuconf.h

#### Testing Notes
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11 changes: 10 additions & 1 deletion drivers/chibios/ws2812_pwm.c
Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,15 @@
# error "please consult your MCU's datasheet and specify in your config.h: #define WS2812_DMAMUX_ID STM32_DMAMUX1_TIM?_UP"
#endif

#ifndef WS2812_PWM_COMPLEMENTARY_OUTPUT
# define WS2812_PWM_OUTPUT_MODE PWM_OUTPUT_ACTIVE_HIGH
#else
# if !STM32_PWM_USE_ADVANCED
# error "WS2812_PWM_COMPLEMENTARY_OUTPUT requires STM32_PWM_USE_ADVANCED == TRUE"
# endif
# define WS2812_PWM_OUTPUT_MODE PWM_COMPLEMENTARY_OUTPUT_ACTIVE_HIGH
#endif

// Push Pull or Open Drain Configuration
// Default Push Pull
#ifndef WS2812_EXTERNAL_PULLUP
Expand Down Expand Up @@ -247,7 +256,7 @@ void ws2812_init(void) {
.channels =
{
[0 ... 3] = {.mode = PWM_OUTPUT_DISABLED, .callback = NULL}, // Channels default to disabled
[WS2812_PWM_CHANNEL - 1] = {.mode = PWM_OUTPUT_ACTIVE_HIGH, .callback = NULL}, // Turn on the channel we care about
[WS2812_PWM_CHANNEL - 1] = {.mode = WS2812_PWM_OUTPUT_MODE, .callback = NULL}, // Turn on the channel we care about
},
.cr2 = 0,
.dier = TIM_DIER_UDE, // DMA on update event for next period
Expand Down