探索者F407，PA7引脚复用为TIM14的疑问

2019-07-20 12:12发布

看了探索者F407的第33讲视频，PWM输出实验，视频中使用PF9引脚复用为TIM14，我改用PA7复用为TIM14，为什么实现不出效果？是需要关闭某些功能吗？附上代码：请大神指点

#include "pwm.h"
#include "led.h"

void MY_PWM_Init(u32 arr, u32 psc)
{
      TIM_TimeBaseInitTypeDef  TIM_TimeBaseInitStructure;
      TIM_OCInitTypeDef  TIM_OCInitStructure;
      GPIO_InitTypeDef  GPIO_InitStructure;

      RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM14, ENABLE);
      RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);    //使能 GPIOA时钟
      GPIO_PinAFConfig(GPIOA, GPIO_PinSource7, GPIO_AF_TIM14); //选择 GPIOA_Pin_7

      GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
      GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
      GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;                            //还有这里
      GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
      GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
      GPIO_Init(GPIOA, &GPIO_InitStructure);                               // 这里

      TIM_TimeBaseInitStructure.TIM_Period = arr;
      TIM_TimeBaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;
      TIM_TimeBaseInitStructure.TIM_Prescaler = psc;
      TIM_TimeBaseInitStructure.TIM_ClockDivision = TIM_CKD_DIV1;
      TIM_TimeBaseInit(TIM14, &TIM_TimeBaseInitStructure);

      TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
      TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
      TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;
      TIM_OC1Init(TIM14, &TIM_OCInitStructure);

      TIM_OC1PreloadConfig(TIM14, TIM_OCPreload_Enable);
      TIM_ARRPreloadConfig(TIM14, ENABLE);

      TIM_Cmd(TIM14, ENABLE);
}

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