esp 32 MCPWM esp32mcpwm占空比怎么算

esp32外设使用-MCPWM载波模块使用

• 概述
• 关键函数说明
• 示例程序

概述

载波模块主要用在PWM输出信号与驱动器之间通过变压器隔离的应用，使用高频载波对PWM进行调制输出。如下图所示的波形，第一个脉冲宽度可单独配置，目的在于提供高能量脉冲以接通电源开关；随后的脉冲可整体调整频率和占空比，用于保持上电的状态。

关键函数说明

注意载波配置需在mcpwm_init()函数之后，否则载波无输出。

//载波模块配置
mcpwm_carrier_config_t car_cfg = {
    .carrier_period = 1,                          // 载波周期：1-16;  载波周期 = (carrier_period + 1)*800ns
    .carrier_duty = 1,                            // 载波占空比：1-8; 载波占空比 = carrier_duty * 12.5%
    .pulse_width_in_os = 1,                       //第一个脉冲宽度 1-16;  第一个脉冲宽度 = (载波周期)*(pulse_width_in_os + 1)
    .carrier_os_mode = MCPWM_ONESHOT_MODE_EN,     //开启/关闭第一个脉冲设置：MCPWM_ONESHOT_MODE_EN / MCPWM_ONESHOT_MODE_DIS
    .carrier_ivt_mode = MCPWM_CARRIER_OUT_IVT_DIS //输出载波是否反相：MCPWM_CARRIER_OUT_IVT_EN / MCPWM_CARRIER_OUT_IVT_DIS
};
//初始化载波模块
ESP_ERROR_CHECK(mcpwm_carrier_init(
    MCPWM_UNIT_0,  // MCPWM_UNIT_0/1
    MCPWM_TIMER_0, // MCPWM_TIMER_0/1/2
    &car_cfg));
//启动载波输出
ESP_ERROR_CHECK(mcpwm_carrier_enable(
    MCPWM_UNIT_0,    // MCPWM_UNIT_0/1
    MCPWM_TIMER_0)); // MCPWM_TIMER_0/1/2
//关闭载波输出
esp_err_t mcpwm_carrier_disable(mcpwm_unit_t mcpwm_num, mcpwm_timer_t timer_num)
//设置载波周期
esp_err_t mcpwm_carrier_set_period(mcpwm_unit_t mcpwm_num, mcpwm_timer_t timer_num, uint8_t carrier_period)
//设置载波占空比
esp_err_t mcpwm_carrier_set_duty_cycle(mcpwm_unit_t mcpwm_num, mcpwm_timer_t timer_num, uint8_t carrier_duty)
//开启第一个脉冲配置
esp_err_t mcpwm_carrier_oneshot_mode_enable(mcpwm_unit_t mcpwm_num, mcpwm_timer_t timer_num, uint8_t pulse_width)
//关闭第一个脉冲配置
esp_err_t mcpwm_carrier_oneshot_mode_disable(mcpwm_unit_t mcpwm_num, mcpwm_timer_t timer_num)
//载波输出反相设置
esp_err_t mcpwm_carrier_output_invert(mcpwm_unit_t mcpwm_num, mcpwm_timer_t timer_num, mcpwm_carrier_out_ivt_t carrier_ivt_mode)

示例程序

该程序对输出100Hz占空比为30%的PWM波进行调制输出，配置载波周期为1600ns，载波占空比为12.5%，载波第一个脉冲宽度为3200ns。

#include <stdio.h>
#include "sdkconfig.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "esp_system.h"
#include "esp_spi_flash.h"

#include "string.h"
#include "driver/mcpwm.h"

#define io_num(x) x

void app_main(void)
{
    // mcpwm IO配置
    mcpwm_pin_config_t mcpwm_pin = {
        .mcpwm0a_out_num = io_num(14), //实际IO号
        .mcpwm0b_out_num = io_num(15),
        .mcpwm1a_out_num = -1,
        .mcpwm1b_out_num = -1,
        .mcpwm2a_out_num = -1,
        .mcpwm2b_out_num = -1,
        .mcpwm_cap0_in_num = -1,
        .mcpwm_cap1_in_num = -1,
        .mcpwm_cap2_in_num = -1,
        .mcpwm_sync0_in_num = -1, // Not used
        .mcpwm_sync1_in_num = -1, // Not used
        .mcpwm_sync2_in_num = -1, // Not used
        .mcpwm_fault0_in_num = -1,
        .mcpwm_fault1_in_num = -1, // Not used
        .mcpwm_fault2_in_num = -1  // Not used
    };
    ESP_ERROR_CHECK(mcpwm_set_pin(MCPWM_UNIT_0, &mcpwm_pin));
    //设置PWM定时器分辨率
    ESP_ERROR_CHECK(mcpwm_group_set_resolution(MCPWM_UNIT_0, 10000000));               // MCPWM号(0/1)、分辨率(默认：10,000,000)
    ESP_ERROR_CHECK(mcpwm_timer_set_resolution(MCPWM_UNIT_0, MCPWM_TIMER_0, 1000000)); //定时器号(0/1/2)、分辨率(默认：1,000,000)

    mcpwm_config_t mcpwm_conf = {
        .frequency = 100, //输出pwm波形频率 Hz
        .cmpr_a = 30,     //操作器A输出占空比, i.e duty_a = 62.3
        .cmpr_b = 0,      //操作器B输出占空比, i.e duty_a = 42.8
        /*******************************************
         *duty_mode (占空比类型)：
         *	MCPWM_DUTY_MODE_0： 高有效，例如：%20占空比 == 高电平20%
         *	MCPWM_DUTY_MODE_1： 低有效，例如：%20占空比 == 低电平20%
         *	MCPWM_HAL_GENERATOR_MODE_FORCE_LOW： 输出强制为低
         *	MCPWM_HAL_GENERATOR_MODE_FORCE_HIGH：输出强制为高
         *	MCPWM_DUTY_MODE_MAX：Num of duty cycle modes
         ********************************************/
        .duty_mode = MCPWM_DUTY_MODE_0,
        /****************************************
         * counter_mode (计数模式):
         * 	MCPWM_FREEZE_COUNTER: 计数器冻结
         * 	MCPWM_UP_COUNTER:  计数器递增,左对齐，频率不变
         * 	MCPWM_DOWN_COUNTER: 计数器递减,右对齐，频率不变
         * 	MCPWM_UP_DOWN_COUNTER：计数器递增递减，中间对齐，频率减半
         ********************************************/
        .counter_mode = MCPWM_UP_COUNTER};
    ESP_ERROR_CHECK(mcpwm_init(MCPWM_UNIT_0, MCPWM_TIMER_0, &mcpwm_conf)); //启动定时器0

//载波模块配置
mcpwm_carrier_config_t car_cfg = {
    .carrier_period = 1,                          // 载波周期：1-16;  载波周期 = (carrier_period + 1)*800ns
    .carrier_duty = 1,                            // 载波占空比：1-8; 载波占空比 = carrier_duty * 12.5%
    .pulse_width_in_os = 1,                       //第一个脉冲宽度 1-16;  第一个脉冲宽度 = (载波周期)*(pulse_width_in_os + 1)
    .carrier_os_mode = MCPWM_ONESHOT_MODE_EN,     //开启/关闭第一个脉冲设置：MCPWM_ONESHOT_MODE_EN / MCPWM_ONESHOT_MODE_DIS
    .carrier_ivt_mode = MCPWM_CARRIER_OUT_IVT_DIS //输出载波是否反相：MCPWM_CARRIER_OUT_IVT_EN / MCPWM_CARRIER_OUT_IVT_DIS
};
ESP_ERROR_CHECK(mcpwm_carrier_init(
    MCPWM_UNIT_0,  // MCPWM_UNIT_0/1
    MCPWM_TIMER_0, // MCPWM_TIMER_0/1/2
    &car_cfg));
ESP_ERROR_CHECK(mcpwm_carrier_enable(
    MCPWM_UNIT_0,    // MCPWM_UNIT_0/1
    MCPWM_TIMER_0)); // MCPWM_TIMER_0/1/2
}

效果