一、快速运行

• 示例项目中，选择peripherals—>rmt—>led_strip
• menuconfig配置ESP32C3-Specific—>Rec 0
• 芯片选择ESP32-C3(Built-in USB JTAG)
• 快速运行ESP-IDF Build, Flash and Monitor（左下角）

二、运行效果

三、硬件说明

从硬件原理图中可以看出来

• RGB LED是通过GPIO8来控制
• 而RGB LED是SK68XXMINI-HS
• 大部分人对SK68XXMINI不熟悉，但是对WS2812熟悉
• 查一下资料就晓得，SK68XXMINI和WS2812其实是一个东西，控制原理是一样的
• SK68XXMINI资料
• WS2812资料，WS2812资料2
  
  

四、RMT简介

RMT 是 Remote Control 的简称。由于RMT模块的灵活性，驱动器还可用于生成或接收许多其他类型的信号。

WS2812是一个数字RGB LED，其定义的协议数据格式与RMT外围设备中的协议数据格式兼容。

• RMT发送
  
• RMT接收
  

五、例程说明

• RMT配置rmt_config
  • rmt_mode = RMT_MODE_TX输出模式
  • channel通道号
  • gpio_numGPIO口
  • 其他
• RMT驱动安装rmt_driver_install
  • channel通道号
  • rx_buf_size = 0接收缓存大小
  • intr_alloc_flags = 0
• led_strip配置LED_STRIP_DEFAULT_CONFIG
  • max_leds最大LED个数
  • dev设备手柄，即RMT通道号的地址
• led_strip实例化led_strip_new_rmt_ws2812
  • led_strip_config_t led_strip配置参数
• led_strip实例化后有多个方法
  • esp_err_t (*set_pixel)(led_strip_t *strip, uint32_t index, uint32_t red, uint32_t green, uint32_t blue);为特定像素设置RGB
  • esp_err_t (*refresh)(led_strip_t *strip, uint32_t timeout_ms);刷新LEDs颜色
  • esp_err_t (*clear)(led_strip_t *strip, uint32_t timeout_ms);关闭所有LEDs
  • esp_err_t (*del)(led_strip_t *strip);释放LEDs所有资源
• while循环
  • hue从0到360的阶梯递增
  • hue转rgb
  • strip->set_pixel(strip, j, red, green, blue)设置RGB进去到第j个LED
  • strip->refresh(strip, 100)刷新LED的颜色
  • 延时
  • strip->clear(strip, 50);关闭所有LEDs
  • 延时
  • 循环……

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、优化与效果

我感觉这个效果在我这个开发板上面效果不咋地，所以我做了如下优化

• 首先，RMT TX的GPIO在开发板上面是GPIO8，所以，#define EXAMPLE_RMT_TX_GPIO 8
• 其次，RGB LED我就一个，所以，#define EXAMPLE_STRIP_LED_NUMBER 1
• 最后，hue递增，再转rgb的方式，太骚了，不适合我。我直接红绿蓝RGB三种颜色每秒流转即可

改动后效果如下：

改动代码如下：

#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、相关函数说明

7.1 rmt 相关

\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 相关

\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、参考

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

觉得好，就一键三连呗（点赞+收藏+关注）