7.1-I2C的中断

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分类专栏：嵌入式开发 STM32 文章标签： stm32 嵌入式硬件单片机

于 2024-10-13 20:33:18 首次发布

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I2C的中断与DMA

回顾

HAL_I2C_MASTER_Transmit(&hi2c1,ADRESS,PDate,Size,Time);


HAL_I2C_MASTER_Receive(&hi2c1,ADRESS,PDate,Size,Time);

通信具体过程如下：
在这里插入图片描述

在I2C的轮询模式中

发送时：CPU将以主机0x70 发送从机 ACK 回复主机0xAC发送 ACK 回复主机 0x33 从机ACK…全部发送且接收完成后，才会空闲下来，去处理其他指令，

接收时，也是类似，整个发送或者接收过程中，一直阻塞执行，占用着CPU资源。完成后才回去处理其他代码。

为了解决上述CPU阻塞情况，I2C也有中断模式与DMA模式

中断模式：

CPU发送一字节的数据0x70后，CPU就去执行其他正常任务，直到此字节数据发送成功后（从机返回ACK信号）产生中断 CPU 再来塞入下一字节的数据。

DMA模式：

整个发送或者接收的数据都交给小助手DMA去搬运，等数据接收或者发送完成过，再有DMA通过中断通知CPU前来处理

两种模式的用法与串口一样

I2C设置中断：

1.在图形界面开启NVIC Settings 中开启中断，本次主要用到事件中断向量。

在这里插入图片描述

下面用I2C的中断模式改造AHT20_Read()函数

HAL_I2C_Master_Transmit_IT(&hi2c1, ADDRESS, pData, Size);

参数与前面相同，不需要等待的时间

void AHT20_Read(float *Temperature, float *Humidty){
    uint8_t sendBuffer[3] = {0xAC,0x33,0x00};
    uint8_t readBuffer[6] = {0};

    HAL_I2C_Master_Transmit_IT(&hi2c1, AHT20_ADDRESS, sendBuffer, 3, HAL_MAX_DELAY);
    HAL_Delay(75);
    HAL_I2C_Master_Receive_IT(&hi2c1, AHT20_ADDRESS , readBuffer, 6 , HAL_MAX_DELAY);
    
    
    if( (readBuffer[0] & 0x80 ) == 0x00) {
    	//计算
    	uint32_t data = 0;
    	data  = ((uint32_t)readBuffer[3]>>4)+((uint32_t)readBuffer[2]  << 4) + ((uint32_t)readBuffer[1]<<12);
    	*Humidty = data * 100.0f / (1<<20);

    	data = (((uint32_t)readBuffer[3]  &  0x0f )<<16 )  +   ((uint32_t)readBuffer[4]  << 8) + ((uint32_t)readBuffer[5]);
    	*Temperature = data *  200.0f/(1<<20) - 50;
	}
}

只是简单的修改并不能达到设想的效果，是因为

中断和DMA模式是非阻塞模式，他们将任务交给外设后就会接着向下执行。并不会等待数据的发送/接收完成，整个通信流程都交给外设与中断进行控制，通信完成后，再通过中断来通知我们。所以后面的对数据的处理前的Receive只是通知外设进行了读取。但尚未读取完成，readBuffer里的数据都是我们初始化的0，解析出的数据自然就不对了

解决办法：将步骤拆解。将AHT20_Read()函数分解，分解成三个AHT20_Send()、AHT20_Get()、AHT20_Analysis().并在aht20.h中声明。


void AHT20_Send(){
	static uint8_t sendBuffer[3] = {0xAC,0x33,0x00};  //static将变量空间保留，不被回收
	HAL_I2C_Master_Transmit_IT(&hi2c1, AHT20_ADDRESS, sendBuffer, 3);
}


uint8_t readBuffer[6] = {0};


void AHT20_Get(){
	HAL_I2C_Master_Receive_IT(&hi2c1, AHT20_ADDRESS , readBuffer, 6);
}

void AHT20_Analysis(float *Temperature, float *Humidty){

	 if( (readBuffer[0] & 0x80 ) == 0x00) {
	    	//计算
	    	uint32_t data = 0;
	    	data  = ((uint32_t)readBuffer[3]>>4)+((uint32_t)readBuffer[2]  << 4) + ((uint32_t)readBuffer[1]<<12);
	    	*Humidty = data * 100.0f / (1<<20);

	    	data = (((uint32_t)readBuffer[3]  &  0x0f )<<16 )  +   ((uint32_t)readBuffer[4]  << 8) + ((uint32_t)readBuffer[5]);
	    	*Temperature = data *  200.0f/(1<<20) - 50;
		}
}

在main.c中编写状态机

常用的一种编程方式：状态机编程

在这里插入图片描述

AHT20_Init();
  
  float temperature;
  float humidity;
  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */
	  if (aht20State == 0) {
		AHT20_Send();
		aht20State == 1;
	}else if (aht20State == 1) {
		
	}else if (aht20State == 2) {
		HAL_Delay(75);
		AHT20_Get();
		aht20State = 3;
	}else if (aht20State == 3) {
		
	}else if (aht20State == 4) {
		AHT20_Analysis(&temperature, &humidity);
		sprintf(message,"温度：%.1f\t 湿度：%.1f%%\t\r",temperature,humidity);

		HAL_UART_Transmit(&huart2, (uint8_t *)message, strlen(message), HAL_MAX_DELAY);
		HAL_Delay(1000);
		aht20State = 0;
	}

对于①②的代码，需要在stm32f1xx_hal_i2c.c中寻找这两个状态。

在这里插入图片描述

提示文件较大，点击YES后按下图更改

在这里插入图片描述

其中

__weak void HAL_I2C_MasterTxCpltCallback(I2C_HandleTypeDef *hi2c)
{
  /* Prevent unused argument(s) compilation warning */
  UNUSED(hi2c);

  /* NOTE : This function should not be modified, when the callback is needed,
            the HAL_I2C_MasterTxCpltCallback could be implemented in the user file
   */
}

__weak void HAL_I2C_MasterRxCpltCallback(I2C_HandleTypeDef *hi2c)
{
  /* Prevent unused argument(s) compilation warning */
  UNUSED(hi2c);

  /* NOTE : This function should not be modified, when the callback is needed,
            the HAL_I2C_MasterRxCpltCallback could be implemented in the user file
   */
}

MasterTxCpltCallback是I2C数据全部发送完成时的回调函数，MasterRxCpltCallback是I2C数据全部接收完成时的回调函数，

把他们在i2c.c文件中重新实现一下 USER CODE BEGIN0对儿中：

void HAL_I2C_MasterTxCpltCallback(I2C_HandleTypeDef *hi2c){
	  //此函数会在通过Transmit_IT函数发送的命令数据全部送达到从机后，由I2C中断调用
	 
   if (hi2c==&hi2c1) {  //判断是否是i2c1引起的中断
		aht20State = 2;
	}
}

void HAL_I2C_MasterRxCpltCallback(I2C_HandleTypeDef *hi2c){
	if (hi2c==&hi2c1) {
    aht20State = 4;
	}
}

aht20State要在i2c.c中调用因此在mian.h的USER CODE BEGIN EC中将aht20State设置为外部函数，可在i2c.c中使用。

extern uint8_t aht20State ;

完整代码

mian.c

----
/* USER CODE BEGIN PV */
uint8_t aht20State = 0;   //0初始状态   1 正在发送测量命令，
						  //2. 测量完成等待75ms后读取AHT20数据  3.读取中
						//4.读取完成，解析并展开数据然后恢复到初始状态
/* USER CODE END PV */
----
/* USER CODE BEGIN 2 */
  AHT20_Init();

  float temperature;
  float humidity;
  char message[50];

  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */
	  if (aht20State == 0) {
		AHT20_Send();
		aht20State = 1;
	}else if (aht20State == 1) {

	}else if (aht20State == 2) {
		HAL_Delay(75);
		AHT20_Get();
		aht20State = 3;
	}else if (aht20State == 3) {

	}else if (aht20State == 4) {
		AHT20_Analysis(&temperature, &humidity);
		sprintf(message,"温度：%.1f\t 湿度：%.1f%%\t\r",temperature,humidity);

		HAL_UART_Transmit(&huart2, (uint8_t *)message, strlen(message), HAL_MAX_DELAY);
		HAL_Delay(1000);
		aht20State = 0;
	}

    /* USER CODE BEGIN 3 */

mian.h中

/* USER CODE BEGIN EC */
extern uint8_t aht20State ;
/* USER CODE END EC */

aht20.h

#ifndef INC_AHT20_H_
#define INC_AHT20_H_

#include"i2c.h"


void AHT20_Init();
void AHT20_Send();
void AHT20_Get();
void AHT20_Analysis(float *Temperature, float *Humidty);

#endif /* INC_AHT20_H_ */

aht20.c

#include"aht20.h"

#define AHT20_ADDRESS 0x70

void AHT20_Init(){
    uint8_t readBuffer;
	HAL_Delay(40);

	HAL_I2C_Master_Receive(&hi2c1, AHT20_ADDRESS , &readBuffer, 1 , HAL_MAX_DELAY);

	if ((readBuffer  &  0x08) == 0x00) {
		uint8_t sendBuffer[3] = { 0xBE , 0x08 , 0x00 };
		HAL_I2C_Master_Transmit(&hi2c1, AHT20_ADDRESS, sendBuffer, 3, HAL_MAX_DELAY);
	}

}


void AHT20_Send(){
	static uint8_t sendBuffer[3] = {0xAC,0x33,0x00};  //static将变量空间保留，不被回收
	HAL_I2C_Master_Transmit_IT(&hi2c1, AHT20_ADDRESS, sendBuffer, 3);
}


uint8_t readBuffer[6] = {0};


void AHT20_Get(){
	HAL_I2C_Master_Receive_IT(&hi2c1, AHT20_ADDRESS , readBuffer, 6);
}

void AHT20_Analysis(float *Temperature, float *Humidty){

	 if( (readBuffer[0] & 0x80 ) == 0x00) {
	    	//计算
	    	uint32_t data = 0;
	    	data  = ((uint32_t)readBuffer[3]>>4)+((uint32_t)readBuffer[2]  << 4) + ((uint32_t)readBuffer[1]<<12);
	    	*Humidty = data * 100.0f / (1<<20);

	    	data = (((uint32_t)readBuffer[3]  &  0x0f )<<16 )  +   ((uint32_t)readBuffer[4]  << 8) + ((uint32_t)readBuffer[5]);
	    	*Temperature = data *  200.0f/(1<<20) - 50;
		}
}

i2c.c中

/* USER CODE BEGIN 0 */

void HAL_I2C_MasterTxCpltCallback(I2C_HandleTypeDef *hi2c){
	  //此函数会在通过Transmit_IT函数发送的命令数据全部送达到从机后，由I2C中断调用

   if (hi2c==&hi2c1) {  //判断是否是i2c1引起的中断
		aht20State = 2;
	}
}

void HAL_I2C_MasterRxCpltCallback(I2C_HandleTypeDef *hi2c){
	if (hi2c==&hi2c1) {
    aht20State = 4;
	}
}
/* USER CODE END 0 */

以上就是i2c的中断模式的应用