相關宏和變量

#define LED_PIN         GPIO_NUM_3
#define LEDC_CHANNEL    LEDC_CHANNEL_0
#define LEDC_TIMER      LEDC_TIMER_0
#define LEDC_MODE       LEDC_LOW_SPEED_MODE
#define LEDC_DUTY_RES   LEDC_TIMER_13_BIT  // 2^13 = 8192級亮度
#define LEDC_FREQUENCY  5000              // 5kHz頻率//呼吸燈效果
int direction = 1;  // 1: 漸亮, -1: 漸暗
int duty = 0;

1.通過ledc_timer_config_t配置PWM參數

下面是結構體源碼

/*** @brief Configuration parameters of LEDC timer for ledc_timer_config function*/
typedef struct {ledc_mode_t speed_mode;                /*!< LEDC speed speed_mode, high-speed mode (only exists on esp32) or low-speed mode */ledc_timer_bit_t duty_resolution;      /*!< LEDC channel duty resolution */ledc_timer_t  timer_num;               /*!< The timer source of channel (0 - LEDC_TIMER_MAX-1) */uint32_t freq_hz;                      /*!< LEDC timer frequency (Hz) */ledc_clk_cfg_t clk_cfg;                /*!< Configure LEDC source clock from ledc_clk_cfg_t.Note that LEDC_USE_RC_FAST_CLK and LEDC_USE_XTAL_CLK arenon-timer-specific clock sources. You can not have one LEDC timer usesRC_FAST_CLK as the clock source and have another LEDC timer uses XTAL_CLKas its clock source. All chips except esp32 and esp32s2 do not havetimer-specific clock sources, which means clock source for all timersmust be the same one. */bool deconfigure;                      /*!< Set this field to de-configure a LEDC timer which has been configured beforeNote that it will not check whether the timer wants to be de-configuredis binded to any channel. Also, the timer has to be paused first beforeit can be de-configured.When this field is set, duty_resolution, freq_hz, clk_cfg fields are ignored. */
} ledc_timer_config_t;

下面是配置

    // 定義 LEDC 定時器配置結構體，用于設置 PWM 信號的“時間基準”（頻率、精度等）ledc_timer_config_t ledc_timer = {.speed_mode = LEDC_MODE,          // LEDC 工作模式（如 LEDC_LOW_SPEED_MODE/LEDC_HIGH_SPEED_MODE）// 低速模式適合普通 GPIO，高速模式需配合特定引腳，由宏定義指定.duty_resolution = LEDC_DUTY_RES, // PWM 占空比分辨率（單位：bit）// 例：若設為 13bit，占空比范圍是 0~2^13-1=8191（數值越大精度越高）.timer_num = LEDC_TIMER,          // 選擇 LEDC 定時器編號（如 LEDC_TIMER_0 ~ LEDC_TIMER_3）// 每個定時器可對應多個通道，實現多路 PWM 輸出.freq_hz = LEDC_FREQUENCY,        // PWM 信號的頻率（單位：Hz）// 例：設為 500Hz，即 PWM 周期為 2ms，人眼無閃爍感.clk_cfg = LEDC_AUTO_CLK,         // LEDC 時鐘源選擇（LEDC_AUTO_CLK 表示自動選擇最優時鐘源）// 也可手動指定（如 LEDC_USE_APB_CLK），自動模式更便捷};// 調用 API 將配置參數寫入 LEDC 定時器硬件寄存器，完成定時器初始化ledc_timer_config(&ledc_timer);

2.通過ledc_channel_config_t配置PWM通道

結構體源碼

/*** @brief Configuration parameters of LEDC channel for ledc_channel_config function*/
typedef struct {int gpio_num;                   /*!< the LEDC output gpio_num, if you want to use gpio16, gpio_num = 16 */ledc_mode_t speed_mode;         /*!< LEDC speed speed_mode, high-speed mode (only exists on esp32) or low-speed mode */ledc_channel_t channel;         /*!< LEDC channel (0 - LEDC_CHANNEL_MAX-1) */ledc_intr_type_t intr_type;     /*!< configure interrupt, Fade interrupt enable  or Fade interrupt disable */ledc_timer_t timer_sel;         /*!< Select the timer source of channel (0 - LEDC_TIMER_MAX-1) */uint32_t duty;                  /*!< LEDC channel duty, the range of duty setting is [0, (2**duty_resolution)] */int hpoint;                     /*!< LEDC channel hpoint value, the range is [0, (2**duty_resolution)-1] */ledc_sleep_mode_t sleep_mode;   /*!< choose the desired behavior for the LEDC channel in Light-sleep */struct {unsigned int output_invert: 1;/*!< Enable (1) or disable (0) gpio output invert */} flags;                        /*!< LEDC flags */} ledc_channel_config_t;

配置

    // 定義 LEDC 通道配置結構體，用于將“定時器生成的時鐘”與“具體 GPIO 引腳”綁定，輸出 PWM 信號ledc_channel_config_t ledc_channel = {.speed_mode = LEDC_MODE,          // 必須與定時器的工作模式一致（低速/高速模式需匹配）.channel = LEDC_CHANNEL,          // 選擇 LEDC 通道編號（如 LEDC_CHANNEL_0 ~ LEDC_CHANNEL_7）// 一個定時器可對應多個通道，實現“同一頻率、不同占空比”的多路 PWM.timer_sel = LEDC_TIMER,          // 綁定的定時器編號（需與上方配置的 LEDC_TIMER 一致）// 表示該通道使用此定時器生成的 PWM 基準時鐘.intr_type = LEDC_INTR_DISABLE,   // 中斷使能配置（LEDC_INTR_DISABLE 表示禁用中斷）// 若需占空比更新完成后觸發中斷，可設為 LEDC_INTR_ENABLE.gpio_num = LED_PIN,              // 輸出 PWM 信號的 GPIO 引腳（如 GPIO_NUM_2）// 需確保該引腳支持 LEDC 功能（參考芯片手冊的引腳功能表）.duty = 0,                        // 初始占空比（需與定時器分辨率匹配，此處初始為 0，LED 熄滅）// 例：分辨率 13bit 時，0 表示占空比 0%（全滅），8191 表示 100%（全亮）.hpoint = 0                       // PWM 高電平起始點（單位：定時器計數周期）// 默認為 0，即定時器計數從 0 開始時輸出高電平，無需特殊調整};// 調用 API 將配置參數寫入 LEDC 通道硬件寄存器，完成通道初始化（此時 GPIO 已開始輸出 PWM）ledc_channel_config(&ledc_channel);

實現

    while (1) {  ledc_set_duty(LEDC_MODE, LEDC_CHANNEL, duty);ledc_update_duty(LEDC_MODE, LEDC_CHANNEL);duty += direction * 100;if (duty >= 8191) { duty = 8191;     direction = -1; }else if (duty <= 0) { duty = 0;        direction = 1;   }vTaskDelay(10 / portTICK_PERIOD_MS);}

流程

一：先配置目標PWM的參數

二：然后配置定時器的PWM輸出到哪個引腳

三：編寫呼吸燈的漸變

四：實現

#include <stdio.h>
#include "driver/ledc.h"
#include "esp_log.h"// 硬件配置定義
#define LED_PIN         GPIO_NUM_3
#define LEDC_CHANNEL    LEDC_CHANNEL_0
#define LEDC_TIMER      LEDC_TIMER_0
#define LEDC_MODE       LEDC_LOW_SPEED_MODE
#define LEDC_DUTY_RES   LEDC_TIMER_13_BIT  // 2^13 = 8192級亮度
#define LEDC_FREQUENCY  5000               // 5kHz頻率static const char *TAG = "BREATHE_LED";/*** @brief 應用程序入口*/
void app_main(void)
{printf("ESP32 Breathe LED Demo Started!\n");printf("LED Pin: GPIO %d\n", LED_PIN);printf("PWM Frequency: %d Hz\n", LEDC_FREQUENCY);printf("PWM Resolution: 13-bit (0-8191)\n");// -------------------------- 1. 配置 LEDC 定時器 ---------------------------ledc_timer_config_t ledc_timer = {.speed_mode = LEDC_MODE,.duty_resolution = LEDC_DUTY_RES,.timer_num = LEDC_TIMER,.freq_hz = LEDC_FREQUENCY,.clk_cfg = LEDC_AUTO_CLK,};ESP_ERROR_CHECK(ledc_timer_config(&ledc_timer));// -------------------------- 2. 配置 LEDC 通道 ---------------------------ledc_channel_config_t ledc_channel = {.speed_mode = LEDC_MODE,.channel = LEDC_CHANNEL,.timer_sel = LEDC_TIMER,.intr_type = LEDC_INTR_DISABLE,.gpio_num = LED_PIN,.duty = 0,.hpoint = 0};ESP_ERROR_CHECK(ledc_channel_config(&ledc_channel));ESP_LOGI(TAG, "Breathe LED initialized on GPIO %d", LED_PIN);// 呼吸燈變量int direction = 1;  // 1: 漸亮, -1: 漸暗int duty = 0;// -------------------------- 3. 呼吸燈主循環 ---------------------------while (1) {// 設置占空比并立即生效（推薦使用這個函數）ESP_ERROR_CHECK(ledc_set_duty_and_update(LEDC_MODE, LEDC_CHANNEL, duty, 0));// 調整占空比duty += direction * 100;// 邊界檢查if (duty >= 8191) {duty = 8191;direction = -1;printf("Reached maximum brightness, starting to fade out...\n");} else if (duty <= 0) {duty = 0;direction = 1;printf("Reached minimum brightness, starting to fade in...\n");}// 簡單的延時（使用空循環實現，不依賴FreeRTOS）// 注意：這種方法會阻塞CPU，在實際應用中建議使用vTaskDelayfor (volatile int i = 0; i < 10000; i++) {// 空循環延時}}
}

說明

esp32的ledc庫專門負責PWM信號的生成