Add crude ws2812b driver.

This driver can run lights! However it is very crude and does not
provide a great API. It does work though! Currently lights up 5 leds of
different colors.

Right now this does synchronous writes, which is not the best. It would
be better to be async, but I think that sholud not be a problem and will
shortly be done.

1 files changed, 68 insertions, 0 deletions

diff --git a/main/drv/ws2812b.c b/main/drv/ws2812b.c
new file mode 100644
index 0000000..aaa3c07
--- /dev/null
+++ b/main/drv/ws2812b.c
@@ -0,0 +1,68 @@
+#include <drv/ws2812b.h>
+
+struct WS2812B {
+  spi_device_handle_t spi_handle;
+};
+
+ws2812b_t* ws2812b_init(spi_device_handle_t spi)
+{
+  ws2812b_t* ret = heap_caps_malloc(sizeof(ws2812b_t), MALLOC_CAP_DEFAULT);
+  ret->spi_handle = spi;
+
+  return ret;
+}
+
+/* Compiles a byte into it's padded serial format. */
+#undef BIT
+#define BIT(b, n) (!!((b) & (1 << (n))))
+static inline void byte_compile(uint8_t byte, uint8_t compl [3])
+{
+  compl [0] = 0 | 1 << 7 | BIT(byte, 7) << 6 | 0 << 5 | 1 << 4 |
+              BIT(byte, 6) << 3 | 0 << 2 | 1 << 1 | BIT(byte, 5) << 0;
+  compl [1] = 0 | 0 << 7 | 1 << 6 | BIT(byte, 4) << 5 | 0 << 4 | 1 << 3 |
+              BIT(byte, 3) << 2 | 0 << 1 | 1 << 0;
+  compl [2] = 0 | BIT(byte, 2) << 7 | 0 << 6 | 1 << 5 | BIT(byte, 1) << 4 |
+              0 << 3 | 1 << 2 | BIT(byte, 0) << 1 | 0 << 0;
+}
+
+static inline void compile(ws2812b_buffer_t* buffer)
+{
+  for (size_t i = 0; i < buffer->n_rgb; ++ i) {
+    byte_compile(buffer->rgb[i].g, buffer->buf_ + i * 9 + 0);
+    byte_compile(buffer->rgb[i].r, buffer->buf_ + i * 9 + 3);
+    byte_compile(buffer->rgb[i].b, buffer->buf_ + i * 9 + 6);
+  }
+}
+
+ws2812b_buffer_t* ws2812b_new_buffer(uint32_t n)
+{
+  ws2812b_buffer_t* ret = heap_caps_malloc(
+      sizeof(ws2812b_buffer_t) + sizeof(ws2812b_rgb_t) * n, MALLOC_CAP_DEFAULT);
+  ret->buf_ = heap_caps_malloc(n * 9, MALLOC_CAP_DMA);
+  ret->n_rgb = n;
+  return ret;
+}
+
+esp_err_t ws2812b_write_sync(ws2812b_t* drv, ws2812b_buffer_t* buffer)
+{
+  esp_err_t err;
+
+  compile(buffer);
+  spi_transaction_t t = { 0 };
+  spi_transaction_t* rt;
+
+  t.tx_buffer = buffer->buf_;
+  t.length = buffer->n_rgb * 9 * 8;
+
+  err = spi_device_queue_trans(drv->spi_handle, &t, portMAX_DELAY);
+  if (err != ESP_OK) {
+    return err;
+  }
+
+  err = spi_device_get_trans_result(drv->spi_handle, &rt, portMAX_DELAY);
+  if (err != ESP_OK) {
+    return err;
+  }
+
+  return ESP_OK;
+}