STM32F100RBTx无法输出PWM信号求助（附代码）

我尝试使用STM32F100RBTx输出PWM信号，但始终无法成功。已经反复核对所有寄存器地址，问题仍然存在。起初不确定烧录是否成功，于是将PB7引脚配置为GPIO输出并连接LED，LED正常点亮，说明烧录及GPIO配置均无问题。以下是我的代码，求排查思路：

TUFAN_VLDCMS_Global.h #

#include <stdint.h>

#define RCC         0x40021000
#define RCC_AHBENR  0x40021014
#define RCC_APB2ENR 0x40021018
#define RCC_APB1ENR 0x4002101C


#define AFIO        0x40010000
#define AFIO_MAPR   0x40010004


#define GPIOB       0x40010C00
#define GPIOB_ODR   0x40010C0C 


#define TIM4        0x40000800  
#define TIM4_CR1    0x40000800 
#define TIM4_CR2    0x40000804
#define TIM4_SMCR   0x40000808
#define TIM4_DIER   0x4000080C
#define TIM4_SR     0x40000810
#define TIM4_EGR    0x40000814
#define TIM4_CCMR1  0x40000818
#define TIM4_CCMR2  0x4000081C
#define TIM4_CCER   0x40000820
#define TIM4_CNT    0x40000824
#define TIM4_PSC    0x40000828
#define TIM4_ARR    0x4000082C
#define TIM4_CCR1   0x40000834
#define TIM4_CCR2   0x40000838
#define TIM4_CCR3   0x4000083C
#define TIM4_CCR4   0x40000840
#define TIM4_DCR    0x40000848
#define TIM4_DMAR   0x4000084C

main.c #

#include <stdio.h>
#include <stdint.h>
#include "TUFAN_VLDCMS_Global.h"


int main(){
    

     volatile uint32_t * tim4Cr1     =  (volatile uint32_t *) TIM4_CR1;
     volatile uint32_t * tim4Psc     =  (volatile uint32_t *) TIM4_PSC;
     volatile uint32_t * tim4Arr     =  (volatile uint32_t *) TIM4_ARR;
     volatile uint32_t * tim4Ccr1    =  (volatile uint32_t *) TIM4_CCR1;
     volatile uint32_t * tim4Ccmr1   =  (volatile uint32_t *) TIM4_CCMR1;
     volatile uint32_t * tim4Ccer    =  (volatile uint32_t *) TIM4_CCER;
     volatile uint32_t * tim4Egr     =  (volatile uint32_t *) TIM4_EGR;


     volatile uint32_t * rccApb1enr  =  (volatile uint32_t *) RCC_APB1ENR;
     volatile uint32_t * rccApb2enr  =  (volatile uint32_t *) RCC_APB2ENR;

     
     
     volatile uint32_t * gpiobCrL    =  (volatile uint32_t *) GPIOB;
     volatile uint32_t * gpiobOdr    =  (volatile uint32_t *) GPIOB_ODR;

     volatile uint32_t * afioMapr    =  (volatile uint32_t *) AFIO_MAPR;

     *rccApb1enr    |= (1<<2);     //enable TIM4 from APB1
     *rccApb2enr    |= (1<<0);     //enable AFIO from APB2
     *rccApb2enr    |= (1<<3);     //enable IOPB from APB2

     *afioMapr      &= ~(1<<12);   //set alternate function remap to 0

     *gpiobCrL      |= (3<<24);    //PB6 Output Mode 50Mhz
     *gpiobCrL      |= (2<<26);    //PB6 Alternate function Push-Pull
     
     *gpiobCrL      |= (3<<28);    //Configuring PB7 to for test to see if i can flash it
     *gpiobCrL      &= ~(3<<30);   

     *tim4Cr1       |= 0x0000;     //reseting it just in case 
     *tim4Psc       =  7;          //calculated it thinking default clock speed is 8MHz
     *tim4Arr       =  62;         //I want to have PWM signal around 16kHz
     *tim4Ccr1      =  31;         //and %50 duty cycle

     *tim4Ccmr1     |= 0x68;       //configuring channel 1
     *tim4Ccer      |= (1<<0);     //enabling channel 1

     *tim4Cr1       |= (1<<0);     //enable the timer
     *tim4Egr       |= (1<<0);

     while (1){
       
          *tim4Ccr1      =  31;
          *gpiobOdr      |= (1<<7);
     }
     
}

排查要点： #

• TIM4 CCMR1配置错误：你用*tim4Ccmr1 |= 0x68的方式配置通道1，可能因为寄存器默认值不为0，导致无关位干扰配置。正确的PWM模式1配置应该先清零对应位再设置：*tim4Ccmr1 = (6 << 4) | (1 << 3);（OC1M设为110启用PWM模式1，OC1PE设为1使能预装载）。
• ARR预装载未开启：需要设置TIM4_CR1的ARPE位（位7），即*tim4Cr1 |= (1 << 7);，确保ARR寄存器的预装载生效，否则定时器参数可能无法正确更新。
• EGR触发时机不合理：建议先触发EGR的UG位更新所有寄存器，再开启定时器，调整顺序为：配置PSC/ARR/CCR1 → 触发EGR → 开启TIM4。
• 冗余代码清理：while循环里反复设置*tim4Ccr1 = 31完全没必要，直接删除即可，避免占用CPU资源。

内容的提问来源于stack exchange，提问作者Rynxie