CH32V103修改的TIM3 PWM无输出是为什么？

用开发板提供的PWM例程修改的tiM3 PWM无输出，TIM1就可以



/********************************** (C) COPYRIGHT *******************************
* File Name          : main.c
* Author             : WCH
* Version            : V1.0.0
* Date               : 2020/04/30
* Description        : Main program body.
*******************************************************************************/


/*
*@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"


/* PWM Output Mode Definition */
#define PWM_MODE1   0
#define PWM_MODE2   1


/* PWM Output Mode Selection */
//#define PWM_MODE PWM_MODE1
#define PWM_MODE PWM_MODE2


/*******************************************************************************
* Function Name  : TIM1_PWMOut_Init
* Description    : Initializes TIM1 PWM output.
* Input          : arr: the period value.
*                  psc: the prescaler value.
* ccp: the pulse value.
* Return         : None
*******************************************************************************/
void TIM1_PWMOut_Init( u16 arr, u16 psc, u16 ccp )
{
GPIO_InitTypeDef GPIO_InitStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;


RCC_APB2PeriphClockCmd( RCC_APB2Periph_GPIOA | RCC_APB2Periph_TIM1, ENABLE );


GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8|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 = arr;
TIM_TimeBaseInitStructure.TIM_Prescaler = psc;
TIM_TimeBaseInitStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit( TIM1, &TIM_TimeBaseInitStructure);


#if (PWM_MODE == PWM_MODE1)
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;


#elif (PWM_MODE == PWM_MODE2)
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;


#endif


TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_Pulse = ccp;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
TIM_OC1Init( TIM1, &TIM_OCInitStructure );
TIM_OC4Init(TIM1,&TIM_OCInitStructure);
TIM_CtrlPWMOutputs(TIM1, ENABLE );
TIM_OC1PreloadConfig( TIM1, TIM_OCPreload_Enable );
    TIM_OC4PreloadConfig( TIM1, TIM_OCPreload_Enable );
TIM_ARRPreloadConfig( TIM1, ENABLE );
TIM_Cmd( TIM1, ENABLE );
}




void TIM3_PWMOut_Init( u16 arr, u16 psc, u16 ccp )
{
    GPIO_InitTypeDef GPIO_InitStructure;
    TIM_OCInitTypeDef TIM_OCInitStructure;
    TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;
    TIM_InternalClockConfig(TIM3); //选择时钟为内部时钟
    RCC_APB2PeriphClockCmd( RCC_APB2Periph_GPIOA|RCC_APB2Periph_GPIOB|RCC_APB1Periph_TIM3, ENABLE );


    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6|GPIO_Pin_7;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init( GPIOA, &GPIO_InitStructure );
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0|GPIO_Pin_1;
    GPIO_Init( GPIOB, &GPIO_InitStructure );


    TIM_TimeBaseInitStructure.TIM_Period = arr;
    TIM_TimeBaseInitStructure.TIM_Prescaler = psc;
    TIM_TimeBaseInitStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit( TIM3, &TIM_TimeBaseInitStructure);


#if (PWM_MODE == PWM_MODE1)
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;


#elif (PWM_MODE == PWM_MODE2)
    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;


#endif


    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    TIM_OCInitStructure.TIM_Pulse = ccp;
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OC1Init( TIM3, &TIM_OCInitStructure );
    TIM_OC2Init(TIM3,&TIM_OCInitStructure);
    TIM_OC3Init(TIM3,&TIM_OCInitStructure);
    TIM_OC4Init(TIM3,&TIM_OCInitStructure);
    TIM_CtrlPWMOutputs(TIM3, ENABLE );
    TIM_OC1PreloadConfig( TIM3, TIM_OCPreload_Enable );
    TIM_OC2PreloadConfig( TIM3, TIM_OCPreload_Enable );
    TIM_OC3PreloadConfig( TIM3, TIM_OCPreload_Enable );
    TIM_OC4PreloadConfig( TIM3, TIM_OCPreload_Enable );
    //TIM_ARRPreloadConfig( TIM3, ENABLE );
    TIM_Cmd( TIM3, ENABLE );
}




/*******************************************************************************
* Function Name  : main
* Description    : Main program.
* Input          : None
* Return         : None
*******************************************************************************/
int main(void)
{
     u16 pwmval=0;
     u8 a=1;
     Delay_Init();
     USART_Printf_Init(115200);
     printf("SystemClk:%drn",SystemCoreClock);


     TIM1_PWMOut_Init( 899, 0, 1000 );
     TIM3_PWMOut_Init( 899, 0, 500 );


     while(1)
     {
         Delay_Ms(1);
         if(a) pwmval++;
         else  pwmval--;
         if(pwmval >500) a =0;
         if(pwmval==0) a =1;
         TIM_SetCompare1(TIM1, pwmval);
         TIM_SetCompare4(TIM1, pwmval);
         TIM_SetCompare1(TIM3, pwmval);
         TIM_SetCompare2(TIM3, pwmval);
         TIM_SetCompare3(TIM3, pwmval);
         TIM_SetCompare4(TIM3, pwmval);


     }
}