diff --git a/examples/common_components/led_strip/led_strip_rmt_ws2812.c b/examples/common_components/led_strip/led_strip_rmt_ws2812.c index 4beaf78f04..345689b93a 100644 --- a/examples/common_components/led_strip/led_strip_rmt_ws2812.c +++ b/examples/common_components/led_strip/led_strip_rmt_ws2812.c @@ -43,6 +43,7 @@ static uint32_t ws2812_t0h_ticks = 0; static uint32_t ws2812_t1h_ticks = 0; static uint32_t ws2812_t0l_ticks = 0; static uint32_t ws2812_t1l_ticks = 0; +static uint32_t ws2812_reset_ticks = 0; typedef struct { led_strip_t parent; @@ -73,24 +74,39 @@ static void IRAM_ATTR ws2812_rmt_adapter(const void *src, rmt_item32_t *dest, si } const rmt_item32_t bit0 = {{{ ws2812_t0h_ticks, 1, ws2812_t0l_ticks, 0 }}}; //Logical 0 const rmt_item32_t bit1 = {{{ ws2812_t1h_ticks, 1, ws2812_t1l_ticks, 0 }}}; //Logical 1 + + const rmt_item32_t reset = {{{ ws2812_reset_ticks, 0, 0, 0 }}}; // Reset signal + const rmt_item32_t nop = {{{ 0, 0, 0, 0 }}}; // Null signal + size_t size = 0; size_t num = 0; uint8_t *psrc = (uint8_t *)src; rmt_item32_t *pdest = dest; - while (size < src_size && num < wanted_num) { - for (int i = 0; i < 8; i++) { - // MSB first - if (*psrc & (1 << (7 - i))) { - pdest->val = bit1.val; - } else { - pdest->val = bit0.val; - } - num++; - pdest++; + while (size < (src_size - 1) && num < wanted_num) { + // MSB first, so we decremented `i` from 7 to 0. + // Note that `i` must be signed (e.g. `int`) for this to work! + for (int i = 7; i >= 0; i--) { + (pdest++)->val = (*psrc & (1 << i)) ? bit1.val : bit0.val; } + num += 8; size++; psrc++; } + // Send reset signal (LOW for `WS2812_RESET_US` microseconds) + // The check of the size is still needed, because `src_size` could be 0. + // (Note that the check could be replaced by `src_size > 0`, + // but it is more clear this way.) + if (size < src_size && num < wanted_num) { + (pdest++)->val = reset.val; // The first bit is the reset signal + // we just sent the first bit, so we start the loop with i = 1 + for (int i = 1; i < 8; i++) { // complete the byte with 7 NOP signals + (pdest++)->val = nop.val; + } + num += 8; + size++; + // we don't need to increment `psrc`, because we no longer use it + } + *translated_size = size; *item_num = num; } @@ -101,7 +117,7 @@ static esp_err_t ws2812_set_pixel(led_strip_t *strip, uint32_t index, uint32_t r ws2812_t *ws2812 = __containerof(strip, ws2812_t, parent); STRIP_CHECK(index < ws2812->strip_len, "index out of the maximum number of leds", err, ESP_ERR_INVALID_ARG); uint32_t start = index * 3; - // In thr order of GRB + // In the order of GRB ws2812->buffer[start + 0] = green & 0xFF; ws2812->buffer[start + 1] = red & 0xFF; ws2812->buffer[start + 2] = blue & 0xFF; @@ -114,7 +130,7 @@ static esp_err_t ws2812_refresh(led_strip_t *strip, uint32_t timeout_ms) { esp_err_t ret = ESP_OK; ws2812_t *ws2812 = __containerof(strip, ws2812_t, parent); - STRIP_CHECK(rmt_write_sample(ws2812->rmt_channel, ws2812->buffer, ws2812->strip_len * 3, true) == ESP_OK, + STRIP_CHECK(rmt_write_sample(ws2812->rmt_channel, ws2812->buffer, ws2812->strip_len * 3 + 1, true) == ESP_OK, "transmit RMT samples failed", err, ESP_FAIL); return rmt_wait_tx_done(ws2812->rmt_channel, pdMS_TO_TICKS(timeout_ms)); err: @@ -141,8 +157,8 @@ led_strip_t *led_strip_new_rmt_ws2812(const led_strip_config_t *config) led_strip_t *ret = NULL; STRIP_CHECK(config, "configuration can't be null", err, NULL); - // 24 bits per led - uint32_t ws2812_size = sizeof(ws2812_t) + config->max_leds * 3; + // 24 bits per led + reset + uint32_t ws2812_size = sizeof(ws2812_t) + config->max_leds * 3 + 1; ws2812_t *ws2812 = calloc(1, ws2812_size); STRIP_CHECK(ws2812, "request memory for ws2812 failed", err, NULL); @@ -155,6 +171,7 @@ led_strip_t *led_strip_new_rmt_ws2812(const led_strip_config_t *config) ws2812_t0l_ticks = (uint32_t)(ratio * WS2812_T0L_NS); ws2812_t1h_ticks = (uint32_t)(ratio * WS2812_T1H_NS); ws2812_t1l_ticks = (uint32_t)(ratio * WS2812_T1L_NS); + ws2812_reset_ticks = (uint32_t)(ratio * WS2812_RESET_US * 1000); // set ws2812 to rmt adapter rmt_translator_init((rmt_channel_t)config->dev, ws2812_rmt_adapter);