STM32F4 ETR計數

本例适用于STM32F4，其餘版本相應修改即可

void TIM_ETR_Init(void)

{

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

GPIO_InitTypeDef GPIO_InitStructure;

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4,ENABLE);
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOE, ENABLE);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOE,&GPIO_InitStructure);

GPIO_PinAFConfig(GPIOE,GPIO_PinSource0,GPIO_AF_TIM4);   //開啟第二功能

TIM_TimeBaseStructure.TIM_Period = 0xFFFF; 
TIM_TimeBaseStructure.TIM_Prescaler = 0; 
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; 
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  
TIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure);

TIM_ETRClockMode2Config(TIM4,TIM_ExtTRGPSC_OFF,TIM_ExtTRGPolarity_NonInverted,0);  //外部時鐘源模式2
TIM_SetCounter(TIM4,0);
TIM_Cmd(TIM4, ENABLE);
}
           

之後在要調用的位置調用函數

TIM_GetCounter(TIM4)；就可以獲得目前計數次數

讀取資料之後将計數值清零，用于下次重新開始計數

TIM_SetCounter(TIM4,0);

頻率就等于擷取的計數值除以計時時長。