一、快速運行

示例專案中，選擇peripherals—>rmt—>led_strip
menuconfig配置ESP32C3-Specific—>Rec 0
芯片選擇ESP32-C3(Built-in USB JTAG)
快速運行ESP-IDF Build, Flash and Monitor（左下角）

二、運行效果

ESP32-C3入門教程基礎篇⑧——WS2812 全彩RGB LED燈帶2

三、硬體說明

從硬體原理圖中可以看出來

RGB LED是通過GPIO8來控制
而RGB LED是SK68XXMINI-HS
大部分人對SK68XXMINI不熟悉，但是對WS2812熟悉
查一下資料就曉得，SK68XXMINI和WS2812其實是一個東西，控制原理是一樣的
SK68XXMINI資料
WS2812資料，WS2812資料2

四、RMT簡介

RMT 是 Remote Control 的簡稱，由于RMT模塊的靈活性，驅動器還可用于生成或接收許多其他型別的信號，

WS2812是一個數字RGB LED，其定義的協議資料格式與RMT外圍設備中的協議資料格式兼容，

RMT發送
RMT接收

五、例程說明

RMT配置rmt_config
- rmt_mode = RMT_MODE_TX輸出模式
- channel通道號
- gpio_numGPIO口
- 其他
RMT驅動安裝rmt_driver_install
- channel通道號
- rx_buf_size = 0接收快取大小
- intr_alloc_flags = 0
led_strip配置LED_STRIP_DEFAULT_CONFIG
- max_leds最大LED個數
- dev設備手柄，即RMT通道號的地址
led_strip實體化led_strip_new_rmt_ws2812
- led_strip_config_t led_strip配置引數
led_strip實體化后有多個方法
- esp_err_t (*set_pixel)(led_strip_t *strip, uint32_t index, uint32_t red, uint32_t green, uint32_t blue);為特定像素設定RGB
- esp_err_t (*refresh)(led_strip_t *strip, uint32_t timeout_ms);重繪LEDs顏色
- esp_err_t (*clear)(led_strip_t *strip, uint32_t timeout_ms);關閉所有LEDs
- esp_err_t (*del)(led_strip_t *strip);釋放LEDs所有資源
while回圈
- hue從0到360的階梯遞增
- hue轉rgb
- strip->set_pixel(strip, j, red, green, blue)設定RGB進去到第j個LED
- strip->refresh(strip, 100)重繪LED的顏色
- 延時
- strip->clear(strip, 50);關閉所有LEDs
- 延時
- 回圈……

void app_main(void)
{
    uint32_t red = 0;
    uint32_t green = 0;
    uint32_t blue = 0;
    uint16_t hue = 0;
    uint16_t start_rgb = 0;

    rmt_config_t config = RMT_DEFAULT_CONFIG_TX(CONFIG_EXAMPLE_RMT_TX_GPIO, RMT_TX_CHANNEL);
    // set counter clock to 40MHz
    config.clk_div = 2;

    ESP_ERROR_CHECK(rmt_config(&config));
    ESP_ERROR_CHECK(rmt_driver_install(config.channel, 0, 0));

    // install ws2812 driver
    led_strip_config_t strip_config = LED_STRIP_DEFAULT_CONFIG(CONFIG_EXAMPLE_STRIP_LED_NUMBER, (led_strip_dev_t)config.channel);
    led_strip_t *strip = led_strip_new_rmt_ws2812(&strip_config);
    if (!strip) {
        ESP_LOGE(TAG, "install WS2812 driver failed");
    }
    // Clear LED strip (turn off all LEDs)
    ESP_ERROR_CHECK(strip->clear(strip, 100));
    // Show simple rainbow chasing pattern
    ESP_LOGI(TAG, "LED Rainbow Chase Start");
    while (true) {
        for (int i = 0; i < 3; i++) {
            for (int j = i; j < CONFIG_EXAMPLE_STRIP_LED_NUMBER; j += 3) {
                // Build RGB values
                hue = j * 360 / CONFIG_EXAMPLE_STRIP_LED_NUMBER + start_rgb;
                led_strip_hsv2rgb(hue, 100, 100, &red, &green, &blue);
                // Write RGB values to strip driver
                ESP_ERROR_CHECK(strip->set_pixel(strip, j, red, green, blue));
            }
            // Flush RGB values to LEDs
            ESP_ERROR_CHECK(strip->refresh(strip, 100));
            vTaskDelay(pdMS_TO_TICKS(EXAMPLE_CHASE_SPEED_MS));
            strip->clear(strip, 50);
            vTaskDelay(pdMS_TO_TICKS(EXAMPLE_CHASE_SPEED_MS));
        }
        start_rgb += 60;
    }
}

六、優化與效果

我感覺這個效果在我這個開發板上面效果不咋地，所以我做了如下優化

首先，RMT TX的GPIO在開發板上面是GPIO8，所以，#define EXAMPLE_RMT_TX_GPIO 8
其次，RGB LED我就一個，所以，#define EXAMPLE_STRIP_LED_NUMBER 1
最后，hue遞增，再轉rgb的方式，太騷了，不適合我，我直接紅綠藍RGB三種顏色每秒流轉即可

改動后效果如下：

ESP32-C3入門教程基礎篇⑧——WS2812 全彩RGB LED燈帶3

改動代碼如下：

#include "sdkconfig.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "esp_log.h"
#include "driver/rmt.h"
#include "led_strip.h"

static const char *TAG = "example";

#define RMT_TX_CHANNEL RMT_CHANNEL_0

#define EXAMPLE_CHASE_SPEED_MS (1000)

#define EXAMPLE_RMT_TX_GPIO 8

#define EXAMPLE_STRIP_LED_NUMBER 1

void app_main(void)
{
    rmt_config_t config = RMT_DEFAULT_CONFIG_TX(EXAMPLE_RMT_TX_GPIO, RMT_TX_CHANNEL);
    // set counter clock to 40MHz
    config.clk_div = 2;

    ESP_ERROR_CHECK(rmt_config(&config));
    ESP_ERROR_CHECK(rmt_driver_install(config.channel, 0, 0));

    // install ws2812 driver
    led_strip_config_t strip_config = LED_STRIP_DEFAULT_CONFIG(EXAMPLE_STRIP_LED_NUMBER, (led_strip_dev_t)config.channel);
    led_strip_t *strip = led_strip_new_rmt_ws2812(&strip_config);
    if (!strip) {
        ESP_LOGE(TAG, "install WS2812 driver failed");
    }
    // Clear LED strip (turn off all LEDs)
    ESP_ERROR_CHECK(strip->clear(strip, 100));
    // Show simple rainbow chasing pattern
    ESP_LOGI(TAG, "LED Rainbow Chase Start");
    while (true) {        
        strip->set_pixel(strip, 0, 255, 0, 0);
        strip->refresh(strip, 50);
        vTaskDelay(pdMS_TO_TICKS(EXAMPLE_CHASE_SPEED_MS));

        strip->set_pixel(strip, 0, 0, 255, 0);
        strip->refresh(strip, 50);
        vTaskDelay(pdMS_TO_TICKS(EXAMPLE_CHASE_SPEED_MS));

        
        strip->set_pixel(strip, 0, 0, 0, 255);
        strip->refresh(strip, 50);
        vTaskDelay(pdMS_TO_TICKS(EXAMPLE_CHASE_SPEED_MS));
    }
}

七、相關函式說明

7.1 rmt 相關

\esp-idf\components\driver\include\driver\rmt.h

/**
* @brief Data struct of RMT configure parameters
*/
typedef struct {
    rmt_mode_t rmt_mode;   /*!< RMT mode: transmitter or receiver */
    rmt_channel_t channel; /*!< RMT channel */
    gpio_num_t gpio_num;   /*!< RMT GPIO number */
    uint8_t clk_div;       /*!< RMT channel counter divider */
    uint8_t mem_block_num; /*!< RMT memory block number */
    uint32_t flags;        /*!< RMT channel extra configurations, OR'd with RMT_CHANNEL_FLAGS_[*] */
    union {
        rmt_tx_config_t tx_config; /*!< RMT TX parameter */
        rmt_rx_config_t rx_config; /*!< RMT RX parameter */
    };
} rmt_config_t;

/**
 * @brief Default configuration for Tx channel
 *
 */
#define RMT_DEFAULT_CONFIG_TX(gpio, channel_id)      \
    {                                                \
        .rmt_mode = RMT_MODE_TX,                     \
        .channel = channel_id,                       \
        .gpio_num = gpio,                            \
        .clk_div = 80,                               \
        .mem_block_num = 1,                          \
        .flags = 0,                                  \
        .tx_config = {                               \
            .carrier_freq_hz = 38000,                \
            .carrier_level = RMT_CARRIER_LEVEL_HIGH, \
            .idle_level = RMT_IDLE_LEVEL_LOW,        \
            .carrier_duty_percent = 33,              \
            .carrier_en = false,                     \
            .loop_en = false,                        \
            .idle_output_en = true,                  \
        }                                            \
    }

components\driver\rmt.c

esp_err_t rmt_config(const rmt_config_t *rmt_param)

esp_err_t rmt_driver_install(rmt_channel_t channel, size_t rx_buf_size, int intr_alloc_flags)

7.2 led strip 相關

\components\led_strip\include\led_strip.h

/**
* @brief LED Strip Configuration Type
*
*/
typedef struct {
    uint32_t max_leds;   /*!< Maximum LEDs in a single strip */
    led_strip_dev_t dev; /*!< LED strip device (e.g. RMT channel, PWM channel, etc) */
} led_strip_config_t;

/**
* @brief Declare of LED Strip Type
*
*/
struct led_strip_s {
    /**
    * @brief Set RGB for a specific pixel
    *
    * @param strip: LED strip
    * @param index: index of pixel to set
    * @param red: red part of color
    * @param green: green part of color
    * @param blue: blue part of color
    *
    * @return
    *      - ESP_OK: Set RGB for a specific pixel successfully
    *      - ESP_ERR_INVALID_ARG: Set RGB for a specific pixel failed because of invalid parameters
    *      - ESP_FAIL: Set RGB for a specific pixel failed because other error occurred
    */
    esp_err_t (*set_pixel)(led_strip_t *strip, uint32_t index, uint32_t red, uint32_t green, uint32_t blue);

    /**
    * @brief Refresh memory colors to LEDs
    *
    * @param strip: LED strip
    * @param timeout_ms: timeout value for refreshing task
    *
    * @return
    *      - ESP_OK: Refresh successfully
    *      - ESP_ERR_TIMEOUT: Refresh failed because of timeout
    *      - ESP_FAIL: Refresh failed because some other error occurred
    *
    * @note:
    *      After updating the LED colors in the memory, a following invocation of this API is needed to flush colors to strip.
    */
    esp_err_t (*refresh)(led_strip_t *strip, uint32_t timeout_ms);

    /**
    * @brief Clear LED strip (turn off all LEDs)
    *
    * @param strip: LED strip
    * @param timeout_ms: timeout value for clearing task
    *
    * @return
    *      - ESP_OK: Clear LEDs successfully
    *      - ESP_ERR_TIMEOUT: Clear LEDs failed because of timeout
    *      - ESP_FAIL: Clear LEDs failed because some other error occurred
    */
    esp_err_t (*clear)(led_strip_t *strip, uint32_t timeout_ms);

    /**
    * @brief Free LED strip resources
    *
    * @param strip: LED strip
    *
    * @return
    *      - ESP_OK: Free resources successfully
    *      - ESP_FAIL: Free resources failed because error occurred
    */
    esp_err_t (*del)(led_strip_t *strip);
};

八、參考

Remote Control (RMT) - ESP32-C2 - —— ESP-IDF編程指南

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ESP32-C3入門教程 基礎篇⑧——WS2812 全彩RGB LED燈帶

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