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-rw-r--r--drivers/chibios/ws2812.c95
1 files changed, 95 insertions, 0 deletions
diff --git a/drivers/chibios/ws2812.c b/drivers/chibios/ws2812.c
new file mode 100644
index 000000000..bdca565d8
--- /dev/null
+++ b/drivers/chibios/ws2812.c
@@ -0,0 +1,95 @@
+#include "quantum.h"
+#include "ws2812.h"
+#include "ch.h"
+#include "hal.h"
+
+/* Adapted from https://github.com/bigjosh/SimpleNeoPixelDemo/ */
+
+#ifndef NOP_FUDGE
+# if defined(STM32F0XX) || defined(STM32F1XX) || defined(STM32F3XX) || defined(STM32F4XX) || defined(STM32L0XX)
+# define NOP_FUDGE 0.4
+# else
+# error("NOP_FUDGE configuration required")
+# define NOP_FUDGE 1 // this just pleases the compile so the above error is easier to spot
+# endif
+#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
+#define NS_PER_CYCLE (NS_PER_SEC / CYCLES_PER_SEC)
+#define NS_TO_CYCLES(n) ((n) / NS_PER_CYCLE)
+
+#define wait_ns(x) \
+ do { \
+ for (int i = 0; i < NS_TO_CYCLES(x); i++) { \
+ __asm__ volatile("nop\n\t" \
+ "nop\n\t" \
+ "nop\n\t" \
+ "nop\n\t" \
+ "nop\n\t" \
+ "nop\n\t"); \
+ } \
+ } while (0)
+
+// These are the timing constraints taken mostly from the WS2812 datasheets
+// These are chosen to be conservative and avoid problems rather than for maximum throughput
+
+#define T1H 900 // Width of a 1 bit in ns
+#define T1L (1250 - T1H) // Width of a 1 bit in ns
+
+#define T0H 350 // Width of a 0 bit in ns
+#define T0L (1250 - T0H) // Width of a 0 bit in ns
+
+// The reset gap can be 6000 ns, but depending on the LED strip it may have to be increased
+// to values like 600000 ns. If it is too small, the pixels will show nothing most of the time.
+#define RES 10000 // Width of the low gap between bits to cause a frame to latch
+
+void sendByte(uint8_t byte) {
+ // WS2812 protocol wants most significant bits first
+ for (unsigned char bit = 0; bit < 8; bit++) {
+ bool is_one = byte & (1 << (7 - bit));
+ // using something like wait_ns(is_one ? T1L : T0L) here throws off timings
+ if (is_one) {
+ // 1
+ writePinHigh(RGB_DI_PIN);
+ wait_ns(T1H);
+ writePinLow(RGB_DI_PIN);
+ wait_ns(T1L);
+ } else {
+ // 0
+ writePinHigh(RGB_DI_PIN);
+ wait_ns(T0H);
+ writePinLow(RGB_DI_PIN);
+ wait_ns(T0L);
+ }
+ }
+}
+
+void ws2812_init(void) { setPinOutput(RGB_DI_PIN); }
+
+// 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;
+ }
+
+ // this code is very time dependent, so we need to disable interrupts
+ chSysLock();
+
+ for (uint8_t i = 0; i < leds; i++) {
+ // WS2812 protocol dictates grb order
+ sendByte(ledarray[i].g);
+ sendByte(ledarray[i].r);
+ sendByte(ledarray[i].b);
+#ifdef RGBW
+ sendByte(ledarray[i].w);
+#endif
+ }
+
+ wait_ns(RES);
+
+ chSysUnlock();
+}