普中STM32-PZ6806L开发板(HAL库函数实现-TIM5捕获上升沿, 获取输入频率)

简介

通过TIM5_CH1捕获上升沿电平, 两个上升沿的计数值计算频率;

电路原理图

连接图

将 PC7 与 PA0使用跳线进行连接

其他知识

APIs
/* Blocking mode: Polling */
HAL_StatusTypeDef HAL_TIM_IC_Start(TIM_HandleTypeDef *htim, uint32_t Channel); // 堵塞捕获开启
HAL_StatusTypeDef HAL_TIM_IC_Stop(TIM_HandleTypeDef *htim, uint32_t Channel); // 堵塞捕获停止
/* Non-Blocking mode: Interrupt */
HAL_StatusTypeDef HAL_TIM_IC_Start_IT(TIM_HandleTypeDef *htim, uint32_t Channel); // 中断捕获开启
HAL_StatusTypeDef HAL_TIM_IC_Stop_IT(TIM_HandleTypeDef *htim, uint32_t Channel); // 中断捕获停止
/* Non-Blocking mode: DMA */
HAL_StatusTypeDef HAL_TIM_IC_Start_DMA(TIM_HandleTypeDef *htim, uint32_t 				Channel, uint32_t *pData, uint16_t Length); //DMA捕获开启
HAL_StatusTypeDef HAL_TIM_IC_Stop_DMA(TIM_HandleTypeDef *htim, uint32_t Channel); // DMA捕获停止
void HAL_TIM_IC_CaptureCallback(TIM_HandleTypeDef *htim); // 捕获时中断回调函数

实现步骤

创建项目

参考普中STM32-PZ6806L开发板(HAL库函数实现-PWM呼吸灯), 使用同一个GPIO口PC7产生PWM，然后PA0引脚进行捕获

初始化PA0为TIM5_CH1

在这里插入图片描述

添加用户代码

main.c

float frequency = 0;
int is_first_captured = 0;
uint32_t ic_val1 = 0, ic_val2 = 0;
uint32_t difference = 0;

void HAL_TIM_IC_CaptureCallback(TIM_HandleTypeDef *htim)
{
	if ( htim->Instance == TIM5 )
	{
		if ( htim->Channel == HAL_TIM_ACTIVE_CHANNEL_1 )
		{
			if (0 == is_first_captured)
			{
				ic_val1 = HAL_TIM_ReadCapturedValue(htim, TIM_CHANNEL_1); // 获取第一个上升沿计数值
				is_first_captured = 1;
			}
			else
			{
				ic_val2 = HAL_TIM_ReadCapturedValue(htim, TIM_CHANNEL_1); // 获取第二个上升沿计数值
				
				/* 计算完整脉冲计数值 */
				if (ic_val2 > ic_val1)
				{
					difference = ic_val2-ic_val1; 
				}
				else if (ic_val2 < ic_val1)
				{
					difference = (0xffff - ic_val1) + ic_val2;
				}
				
				float refClock = 1000000; // System Clock/Prescale = (72000000)/(72); 
				frequency = refClock/difference; // 计算频率
				__HAL_TIM_SET_COUNTER(htim, 0); //reset the counter
				is_first_captured = 0; 
			}
		}

	}
}

int main()
{
	...
	printf("Very Welcome!\r\n");
	
	__HAL_TIM_SET_COMPARE(&htim8, TIM_CHANNEL_2, 250);
	HAL_TIM_PWM_Start(&htim8, TIM_CHANNEL_2); // 启动PWM输出 
	while (1)
  {
		HAL_Delay(2000);
		printf ("frequency : %f\r\n", frequency);
  }
  ...
}