STM32 WS2812 Open Drain Configuration (qmk#9414)

* update docs stm32 only and applies to all 3 driver * cformat
akatrevorjay · Jun 19, 2020 · c785148 · c785148
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diff --git a/docs/ws2812_driver.md b/docs/ws2812_driver.md
@@ -99,3 +99,14 @@ While not an exhaustive list, the following table provides the scenarios that ha
 | f401/f411 | :heavy_check_mark: |
 
 *Other supported ChibiOS boards and/or pins may function, it will be highly chip and configuration dependent.*
+
+### Push Pull and Open Drain Configuration
+The default configuration is a push pull on the defined pin.
+This can be configured for bitbang, PWM and SPI.
+
+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 
+```
diff --git a/drivers/chibios/ws2812.c b/drivers/chibios/ws2812.c
@@ -14,6 +14,14 @@
 #    endif
 #endif
 
+// Push Pull or Open Drain Configuration
+// Default Push Pull
+#ifndef WS2812_EXTERNAL_PULLUP
+#    define WS2812_OUTPUT_MODE PAL_MODE_OUTPUT_PUSHPULL
+#else
+#    define WS2812_OUTPUT_MODE PAL_MODE_OUTPUT_OPENDRAIN
+#endif
+
 #define NUMBER_NOPS 6
 #define CYCLES_PER_SEC (STM32_SYSCLK / NUMBER_NOPS * NOP_FUDGE)
 #define NS_PER_SEC (1000000000L)  // Note that this has to be SIGNED since we want to be able to check for negative values of derivatives
@@ -66,7 +74,7 @@ void sendByte(uint8_t byte) {
     }
 }
 
-void ws2812_init(void) { setPinOutput(RGB_DI_PIN); }
+void ws2812_init(void) { palSetLineMode(RGB_DI_PIN, WS2812_OUTPUT_MODE); }
 
 // Setleds for standard RGB
 void ws2812_setleds(LED_TYPE *ledarray, uint16_t leds) {

diff --git a/drivers/chibios/ws2812_pwm.c b/drivers/chibios/ws2812_pwm.c
@@ -24,6 +24,22 @@
 #    define WS2812_DMA_CHANNEL 2  // DMA Channel for TIMx_UP
 #endif
 
+// Push Pull or Open Drain Configuration
+// Default Push Pull
+#ifndef WS2812_EXTERNAL_PULLUP
+#    if defined(USE_GPIOV1)
+#        define WS2812_OUTPUT_MODE PAL_MODE_STM32_ALTERNATE_PUSHPULL
+#    else
+#        define WS2812_OUTPUT_MODE PAL_MODE_ALTERNATE(WS2812_PWM_PAL_MODE) | PAL_STM32_OTYPE_PUSHPULL | PAL_STM32_OSPEED_HIGHEST | PAL_STM32_PUPDR_FLOATING
+#    endif
+#else
+#    if defined(USE_GPIOV1)
+#        define WS2812_OUTPUT_MODE PAL_MODE_STM32_ALTERNATE_OPENDRAIN
+#    else
+#        define WS2812_OUTPUT_MODE PAL_MODE_ALTERNATE(WS2812_PWM_PAL_MODE) | PAL_STM32_OTYPE_OPENDRAIN | PAL_STM32_OSPEED_HIGHEST | PAL_STM32_PUPDR_FLOATING
+#    endif
+#endif
+
 #ifndef WS2812_PWM_TARGET_PERIOD
 //#    define WS2812_PWM_TARGET_PERIOD 800000 // Original code is 800k...?
 #    define WS2812_PWM_TARGET_PERIOD 80000  // TODO: work out why 10x less on f303/f4x1
@@ -142,11 +158,7 @@ void ws2812_init(void) {
     for (i = 0; i < WS2812_COLOR_BIT_N; i++) ws2812_frame_buffer[i] = WS2812_DUTYCYCLE_0;      // All color bits are zero duty cycle
     for (i = 0; i < WS2812_RESET_BIT_N; i++) ws2812_frame_buffer[i + WS2812_COLOR_BIT_N] = 0;  // All reset bits are zero
 
-#if defined(USE_GPIOV1)
-    palSetLineMode(RGB_DI_PIN, PAL_MODE_STM32_ALTERNATE_PUSHPULL);
-#else
-    palSetLineMode(RGB_DI_PIN, PAL_MODE_ALTERNATE(WS2812_PWM_PAL_MODE) | PAL_STM32_OSPEED_HIGHEST | PAL_STM32_PUPDR_FLOATING);
-#endif
+    palSetLineMode(RGB_DI_PIN, WS2812_OUTPUT_MODE);
 
     // PWM Configuration
     //#pragma GCC diagnostic ignored "-Woverride-init"  // Turn off override-init warning for this struct. We use the overriding ability to set a "default" channel config

diff --git a/drivers/chibios/ws2812_spi.c b/drivers/chibios/ws2812_spi.c
@@ -16,6 +16,22 @@
 #    define WS2812_SPI_MOSI_PAL_MODE 5
 #endif
 
+// Push Pull or Open Drain Configuration
+// Default Push Pull
+#ifndef WS2812_EXTERNAL_PULLUP
+#    if defined(USE_GPIOV1)
+#        define WS2812_OUTPUT_MODE PAL_MODE_STM32_ALTERNATE_PUSHPULL
+#    else
+#        define WS2812_OUTPUT_MODE PAL_MODE_ALTERNATE(WS2812_SPI_MOSI_PAL_MODE) | PAL_STM32_OTYPE_PUSHPULL
+#    endif
+#else
+#    if defined(USE_GPIOV1)
+#        define WS2812_OUTPUT_MODE PAL_MODE_STM32_ALTERNATE_OPENDRAIN
+#    else
+#        define WS2812_OUTPUT_MODE PAL_MODE_ALTERNATE(WS2812_SPI_MOSI_PAL_MODE) | PAL_STM32_OTYPE_OPENDRAIN
+#    endif
+#endif
+
 #define BYTES_FOR_LED_BYTE 4
 #define NB_COLORS 3
 #define BYTES_FOR_LED (BYTES_FOR_LED_BYTE * NB_COLORS)
@@ -52,11 +68,7 @@ static void set_led_color_rgb(LED_TYPE color, int pos) {
 }
 
 void ws2812_init(void) {
-#if defined(USE_GPIOV1)
-    palSetLineMode(RGB_DI_PIN, PAL_MODE_STM32_ALTERNATE_PUSHPULL);
-#else
-    palSetLineMode(RGB_DI_PIN, PAL_MODE_ALTERNATE(WS2812_SPI_MOSI_PAL_MODE) | PAL_STM32_OTYPE_PUSHPULL);
-#endif
+    palSetLineMode(RGB_DI_PIN, WS2812_OUTPUT_MODE);
 
     // TODO: more dynamic baudrate
     static const SPIConfig spicfg = {