关于使用CH32系列MCU定时器输出移相PWM波形

在定时器的输出模式中，有一种输出模式—翻转模式，通过使用该模式，可以使用一个定时器不同通道输出移相PWM波形。关于翻转模式，当核心计数器与比较捕获寄存器的值相同时，翻转该通道的电平。

使用翻转模式配置输出移相PWM波形代码如下：

/********************************** (C) COPYRIGHT *******************************
 * File Name          : main.c
 * Author             : WCH
 * Version            : V1.0.0
 * Date               : 2021/06/06
 * Description        : Main program body.
 * Copyright (c) 2021 Nanjing Qinheng Microelectronics Co., Ltd.
 * SPDX-License-Identifier: Apache-2.0
 *******************************************************************************/

/*
 *@Note
 PWM输出例程：
 TIM1_CH1(PA8)
 本例程演示 TIM_CH1(PA8) 引脚在 PWM模式1和PWM模式2 下，输出 PWM。

*/

#include "debug.h"

/*********************************************************************
 * @fn      TIM1_OutCompare_Init
 *
 * @brief   Initializes TIM1 output compare.
 *
 * @param   arr - the period value.
 *          psc - the prescaler value.
 *          ccp - the pulse value.
 *
 * @return  none
 */
void TIM1_PWMOut_Init(void)
{
    GPIO_InitTypeDef        GPIO_InitStructure={0};
    TIM_OCInitTypeDef       TIM_OCInitStructure={0};
    TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure={0};

    RCC_APB2PeriphClockCmd( RCC_APB2Periph_GPIOA | RCC_APB2Periph_TIM1, ENABLE );

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8|GPIO_Pin_9|GPIO_Pin_10|GPIO_Pin_11;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init( GPIOA, &GPIO_InitStructure );

    TIM_TimeBaseInitStructure.TIM_Period = 4000-1;
    TIM_TimeBaseInitStructure.TIM_Prescaler = 14400-1;
    TIM_TimeBaseInitStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInitStructure.TIM_RepetitionCounter = 0;
    TIM_TimeBaseInit( TIM1, &TIM_TimeBaseInitStructure);


    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Toggle;
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;
    TIM_OCInitStructure.TIM_Pulse = 0;
    TIM_OC1Init( TIM1, &TIM_OCInitStructure );
    TIM_OCInitStructure.TIM_Pulse = 1000;
    TIM_OC2Init( TIM1, &TIM_OCInitStructure );
    TIM_OCInitStructure.TIM_Pulse = 2000;
    TIM_OC3Init( TIM1, &TIM_OCInitStructure );
    TIM_OCInitStructure.TIM_Pulse = 3000;
    TIM_OC4Init( TIM1, &TIM_OCInitStructure );

    TIM_CtrlPWMOutputs(TIM1, ENABLE );
    TIM_OC1PreloadConfig( TIM1, TIM_OCPreload_Disable );
    TIM_OC2PreloadConfig( TIM1, TIM_OCPreload_Disable );
    TIM_OC3PreloadConfig( TIM1, TIM_OCPreload_Disable );
    TIM_OC4PreloadConfig( TIM1, TIM_OCPreload_Disable );

    TIM_ARRPreloadConfig( TIM1, ENABLE );
    TIM_Cmd( TIM1, ENABLE );
}
/*********************************************************************
 * @fn      main
 *
 * @brief   Main program.
 *
 * @return  none
 */
int main(void)
{
    USART_Printf_Init(115200);
    printf("SystemClk:%d\r\n",SystemCoreClock);

    TIM1_PWMOut_Init();

    while(1);
}

程序和正常配置PWM输出代码差不多，只是将PWM模式改为翻转模式，比较寄存器的值要根据移相的需求进行配置，注意大小不要超过设置的重装载值。该种方式配置输出的PWM波形占空比固定为50%。输出波形如下：