PWM DMA based RGB Underglow for STM32 (#7928)

* Add pwm ws2812 driver

* Add docs for pwm ws2812 driver

* Update ws2812_pwm for ChibiOS 19

Co-Authored-By: Nick Brassel <nick@tzarc.org>

Co-authored-by: Nick Brassel <nick@tzarc.org>

1 files changed, 207 insertions, 1 deletions

diff --git a/drivers/arm/ws2812_pwm.c b/drivers/arm/ws2812_pwm.c
index 2094e5009..1a1721029 100644
--- a/drivers/arm/ws2812_pwm.c
+++ b/drivers/arm/ws2812_pwm.c
@@ -1 +1,207 @@
-#error("NOT SUPPORTED")
\ No newline at end of file
+#include "ws2812.h"
+#include "quantum.h"
+#include "hal.h"
+
+/* Adapted from https://github.com/joewa/WS2812-LED-Driver_ChibiOS/ */
+
+#ifdef RGBW
+#    error "RGBW not supported"
+#endif
+
+#ifndef WS2812_PWM_DRIVER
+#    define WS2812_PWM_DRIVER PWMD2  // TIMx
+#endif
+#ifndef WS2812_PWM_CHANNEL
+#    define WS2812_PWM_CHANNEL 2  // Channel
+#endif
+#ifndef WS2812_PWM_PAL_MODE
+#    define WS2812_PWM_PAL_MODE 2  // DI Pin's alternate function value
+#endif
+#ifndef WS2812_DMA_STREAM
+#    define WS2812_DMA_STREAM STM32_DMA1_STREAM2  // DMA Stream for TIMx_UP
+#endif
+#ifndef WS2812_DMA_CHANNEL
+#    define WS2812_DMA_CHANNEL 2  // DMA Channel for TIMx_UP
+#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
+#endif
+
+/* --- PRIVATE CONSTANTS ---------------------------------------------------- */
+
+#define WS2812_PWM_FREQUENCY (STM32_SYSCLK / 2)                             /**< Clock frequency of PWM, must be valid with respect to system clock! */
+#define WS2812_PWM_PERIOD (WS2812_PWM_FREQUENCY / WS2812_PWM_TARGET_PERIOD) /**< Clock period in ticks. 1 / 800kHz = 1.25 uS (as per datasheet) */
+
+/**
+ * @brief   Number of bit-periods to hold the data line low at the end of a frame
+ *
+ * The reset period for each frame must be at least 50 uS; so we add in 50 bit-times
+ * of zeroes at the end. (50 bits)*(1.25 uS/bit) = 62.5 uS, which gives us some
+ * slack in the timing requirements
+ */
+#define WS2812_RESET_BIT_N (50)
+#define WS2812_COLOR_BIT_N (RGBLED_NUM * 24)                   /**< Number of data bits */
+#define WS2812_BIT_N (WS2812_COLOR_BIT_N + WS2812_RESET_BIT_N) /**< Total number of bits in a frame */
+
+/**
+ * @brief   High period for a zero, in ticks
+ *
+ * Per the datasheet:
+ * WS2812:
+ * - T0H: 200 nS to 500 nS, inclusive
+ * - T0L: 650 nS to 950 nS, inclusive
+ * WS2812B:
+ * - T0H: 200 nS to 500 nS, inclusive
+ * - T0L: 750 nS to 1050 nS, inclusive
+ *
+ * The duty cycle is calculated for a high period of 350 nS.
+ */
+#define WS2812_DUTYCYCLE_0 (WS2812_PWM_FREQUENCY / (1000000000 / 350))
+
+/**
+ * @brief   High period for a one, in ticks
+ *
+ * Per the datasheet:
+ * WS2812:
+ * - T1H: 550 nS to 850 nS, inclusive
+ * - T1L: 450 nS to 750 nS, inclusive
+ * WS2812B:
+ * - T1H: 750 nS to 1050 nS, inclusive
+ * - T1L: 200 nS to 500 nS, inclusive
+ *
+ * The duty cycle is calculated for a high period of 800 nS.
+ * This is in the middle of the specifications of the WS2812 and WS2812B.
+ */
+#define WS2812_DUTYCYCLE_1 (WS2812_PWM_FREQUENCY / (1000000000 / 800))
+
+/* --- PRIVATE MACROS ------------------------------------------------------- */
+
+/**
+ * @brief   Determine the index in @ref ws2812_frame_buffer "the frame buffer" of a given bit
+ *
+ * @param[in] led:                  The led index [0, @ref RGBLED_NUM)
+ * @param[in] byte:                 The byte number [0, 2]
+ * @param[in] bit:                  The bit number [0, 7]
+ *
+ * @return                          The bit index
+ */
+#define WS2812_BIT(led, byte, bit) (24 * (led) + 8 * (byte) + (7 - (bit)))
+
+/**
+ * @brief   Determine the index in @ref ws2812_frame_buffer "the frame buffer" of a given red bit
+ *
+ * @note    The red byte is the middle byte in the color packet
+ *
+ * @param[in] led:                  The led index [0, @ref RGBLED_NUM)
+ * @param[in] bit:                  The bit number [0, 7]
+ *
+ * @return                          The bit index
+ */
+#define WS2812_RED_BIT(led, bit) WS2812_BIT((led), 1, (bit))
+
+/**
+ * @brief   Determine the index in @ref ws2812_frame_buffer "the frame buffer" of a given green bit
+ *
+ * @note    The red byte is the first byte in the color packet
+ *
+ * @param[in] led:                  The led index [0, @ref RGBLED_NUM)
+ * @param[in] bit:                  The bit number [0, 7]
+ *
+ * @return                          The bit index
+ */
+#define WS2812_GREEN_BIT(led, bit) WS2812_BIT((led), 0, (bit))
+
+/**
+ * @brief   Determine the index in @ref ws2812_frame_buffer "the frame buffer" of a given blue bit
+ *
+ * @note    The red byte is the last byte in the color packet
+ *
+ * @param[in] led:                  The led index [0, @ref RGBLED_NUM)
+ * @param[in] bit:                  The bit index [0, 7]
+ *
+ * @return                          The bit index
+ */
+#define WS2812_BLUE_BIT(led, bit) WS2812_BIT((led), 2, (bit))
+
+/* --- PRIVATE VARIABLES ---------------------------------------------------- */
+
+static uint32_t ws2812_frame_buffer[WS2812_BIT_N + 1]; /**< Buffer for a frame */
+
+/* --- PUBLIC FUNCTIONS ----------------------------------------------------- */
+/*
+ * Gedanke: Double-buffer type transactions: double buffer transfers using two memory pointers for
+the memory (while the DMA is reading/writing from/to a buffer, the application can
+write/read to/from the other buffer).
+ */
+
+void ws2812_init(void) {
+    // Initialize led frame buffer
+    uint32_t i;
+    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
+
+    // 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
+    static const PWMConfig ws2812_pwm_config = {
+        .frequency = WS2812_PWM_FREQUENCY,
+        .period    = WS2812_PWM_PERIOD,  // Mit dieser Periode wird UDE-Event erzeugt und ein neuer Wert (Länge WS2812_BIT_N) vom DMA ins CCR geschrieben
+        .callback  = NULL,
+        .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
+            },
+        .cr2  = 0,
+        .dier = TIM_DIER_UDE,  // DMA on update event for next period
+    };
+    //#pragma GCC diagnostic pop  // Restore command-line warning options
+
+    // Configure DMA
+    // dmaInit(); // Joe added this
+    dmaStreamAlloc(WS2812_DMA_STREAM - STM32_DMA1_STREAM1, 10, NULL, NULL);
+    dmaStreamSetPeripheral(WS2812_DMA_STREAM, &(WS2812_PWM_DRIVER.tim->CCR[WS2812_PWM_CHANNEL - 1]));  // Ziel ist der An-Zeit im Cap-Comp-Register
+    dmaStreamSetMemory0(WS2812_DMA_STREAM, ws2812_frame_buffer);
+    dmaStreamSetTransactionSize(WS2812_DMA_STREAM, WS2812_BIT_N);
+    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
+
+    // Start DMA
+    dmaStreamEnable(WS2812_DMA_STREAM);
+
+    // Configure PWM
+    // NOTE: It's required that preload be enabled on the timer channel CCR register. This is currently enabled in the
+    // ChibiOS driver code, so we don't have to do anything special to the timer. If we did, we'd have to start the timer,
+    // disable counting, enable the channel, and then make whatever configuration changes we need.
+    pwmStart(&WS2812_PWM_DRIVER, &ws2812_pwm_config);
+    pwmEnableChannel(&WS2812_PWM_DRIVER, WS2812_PWM_CHANNEL - 1, 0);  // Initial period is 0; output will be low until first duty cycle is DMA'd in
+}
+
+void ws2812_write_led(uint16_t led_number, uint8_t r, uint8_t g, uint8_t b) {
+    // Write color to frame buffer
+    for (uint8_t bit = 0; bit < 8; bit++) {
+        ws2812_frame_buffer[WS2812_RED_BIT(led_number, bit)]   = ((r >> bit) & 0x01) ? WS2812_DUTYCYCLE_1 : WS2812_DUTYCYCLE_0;
+        ws2812_frame_buffer[WS2812_GREEN_BIT(led_number, bit)] = ((g >> bit) & 0x01) ? WS2812_DUTYCYCLE_1 : WS2812_DUTYCYCLE_0;
+        ws2812_frame_buffer[WS2812_BLUE_BIT(led_number, bit)]  = ((b >> bit) & 0x01) ? WS2812_DUTYCYCLE_1 : WS2812_DUTYCYCLE_0;
+    }
+}
+
+// Setleds for standard RGB
+void ws2812_setleds(LED_TYPE* ledarray, uint16_t leds) {
+    static bool s_init = false;
+    if (!s_init) {
+        ws2812_init();
+        s_init = true;
+    }
+
+    for (uint16_t i = 0; i < leds; i++) {
+        ws2812_write_led(i, ledarray[i].r, ledarray[i].g, ledarray[i].b);
+    }
+}