【STM32】STM32通过I2C实现温湿度采集与显示

I2C通信时，分为主设备和从设备，其中主设备一个、从设备多个。主设备要主导整个通信过程，从设备根据I2C协议被动的响应主设备；主设备负责调度总线，决定某个时间和其中一个从设备通信。在同一时间，只有主设备和其中一个从设备通信，其余的从设备处于等待状态，等待主设备与其通信；每个从设备在I2C总线上都有唯一的地址，主设备就是通过地址来区分不同的从设备，从而决定和哪一个从设备通信。

2.I2C总线协议

(1)主设备发送一个起始信号； (2)主设备接着发送8bit数据，其中7位是从设备的地址，一位表示此次主设备是要读数据海思写数据； (3)和主设备发送的地址匹配的从设备发出一个ack响应信号； (4)主/从设备将数据发送到SDA总线上，每次传输都是8bit数据； (5)主/从设备从SDA线上接收数据，并发送一个ACK响应信号； (6)还可以接着n个发送和接收的过程； (7)主设备发送停止信号，停止本次通信；

3.软件I2C和硬件I2C

**软件I2C：**软件I2C是通过软件控制GPIO管脚来模拟I2C协议的时序。其

1.可以使用任意的GPIO管脚来实现，可适应不同的硬件平台和需求。 2.不依赖于特定的硬件电路，可在不同的平台上进行移植和使用。 3.可在没有硬件I2C支持的情况下使用，也可以用于扩展硬件I2C的功能。

**硬件I2C：**硬件I2C是通过专门的硬件电路实现的，通常由微控制器或其他集成电路上的硬件模块提供支持。其

1.使用专门的硬件电路，可以实现高速的数据传输。 2.传输过程由硬件电路完成，不需要CPU的干预，因此可以释放CPU的资源。 3.时序由硬件电路控制，不容易受到外部干扰的影响。

二、stm32通过I2C实现温湿度（AHT20）采集

1.stm32cube配置

RCC配置：

SYS配置：

I2C1配置：

USART1配置：

GPIO配置：

时钟配置：

project配置：

2.KEil代码配置

添加AHT20文件：

添加路径：

AHT20.c代码：

/*******************************************/
/*@????:??????????          */
/*@??:?????????                */
/*@??:V1.2                              */
/*******************************************/
//#include "main.h" 
#include "AHT20-21_DEMO_V1_3.h" 
#include "gpio.h"
#include "i2c.h"


void Delay_N10us(uint32_t t)//????
{
  uint32_t k;

   while(t--)
  {
    for (k = 0; k < 2; k++);//110
  }
}

void SensorDelay_us(uint32_t t)//????
{
		
	for(t = t-2; t>0; t--)
	{
		Delay_N10us(1);
	}
}

void Delay_4us(void)		//????
{	
	Delay_N10us(1);
	Delay_N10us(1);
	Delay_N10us(1);
	Delay_N10us(1);
}
void Delay_5us(void)		//????
{	
	Delay_N10us(1);
	Delay_N10us(1);
	Delay_N10us(1);
	Delay_N10us(1);
	Delay_N10us(1);

}

void Delay_1ms(uint32_t t)		//????
{
   while(t--)
  {
    SensorDelay_us(1000);//??1ms
  }
}


//void AHT20_Clock_Init(void)		//????
//{
//	RCC_APB2PeriphClockCmd(CC_APB2Periph_GPIOB,ENABLE);
//}

void SDA_Pin_Output_High(void)   //?PB7????? , ???????, PB7??I2C?SDA
{
	GPIO_InitTypeDef  GPIO_InitStruct;
	GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;//????
	GPIO_InitStruct.Pin = GPIO_PIN_7;
	GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
	HAL_GPIO_Init(GPIOB,& GPIO_InitStruct);
	HAL_GPIO_WritePin(GPIOB,GPIO_PIN_7,GPIO_PIN_SET);
}

void SDA_Pin_Output_Low(void)  //?P7?????  ???????
{
	GPIO_InitTypeDef  GPIO_InitStruct;
	GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;//????
	GPIO_InitStruct.Pin = GPIO_PIN_7;
	GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
	HAL_GPIO_Init(GPIOB,& GPIO_InitStruct);
	HAL_GPIO_WritePin(GPIOB,GPIO_PIN_7,GPIO_PIN_RESET);
}

void SDA_Pin_IN_FLOATING(void)  //SDA???????
{
	GPIO_InitTypeDef  GPIO_InitStruct;
	GPIO_InitStruct.Mode = GPIO_MODE_INPUT;//??
	GPIO_InitStruct.Pin = GPIO_PIN_7;
	GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
	HAL_GPIO_Init( GPIOB,&GPIO_InitStruct);
}


void SCL_Pin_Output_High(void) //SCL?????,P14??I2C?SCL
{
	HAL_GPIO_WritePin(GPIOB,GPIO_PIN_6,GPIO_PIN_SET);
}

void SCL_Pin_Output_Low(void) //SCL?????
{
	HAL_GPIO_WritePin(GPIOB,GPIO_PIN_6,GPIO_PIN_RESET);
}

void Init_I2C_Sensor_Port(void) //???I2C??,??????
{	
	GPIO_InitTypeDef  GPIO_InitStruct;
	GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;//????
	GPIO_InitStruct.Pin = GPIO_PIN_7;
	GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
	HAL_GPIO_Init(GPIOB,& GPIO_InitStruct);
	HAL_GPIO_WritePin(GPIOB,GPIO_PIN_15,GPIO_PIN_SET);

	
	GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;//????
	GPIO_InitStruct.Pin = GPIO_PIN_6;
	GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
	HAL_GPIO_Init(GPIOB,& GPIO_InitStruct);
	HAL_GPIO_WritePin(GPIOB,GPIO_PIN_15,GPIO_PIN_SET);
	
}
void I2C_Start(void)		 //I2C????START??
{
	SDA_Pin_Output_High();
	SensorDelay_us(8);
	SCL_Pin_Output_High();
	SensorDelay_us(8);
	SDA_Pin_Output_Low();
	SensorDelay_us(8);
	SCL_Pin_Output_Low();
	SensorDelay_us(8);   
}


void AHT20_WR_Byte(uint8_t Byte) //?AHT20?????
{
	uint8_t Data,N,i;	
	Data=Byte;
	i = 0x80;
	for(N=0;N<8;N++)
	{
		SCL_Pin_Output_Low(); 
		Delay_4us();	
		if(i&Data)
		{
			SDA_Pin_Output_High();
		}
		else
		{
			SDA_Pin_Output_Low();
		}	
			
    SCL_Pin_Output_High();
		Delay_4us();
		Data <<= 1;
		 
	}
	SCL_Pin_Output_Low();
	SensorDelay_us(8);   
	SDA_Pin_IN_FLOATING();
	SensorDelay_us(8);	
}	


uint8_t AHT20_RD_Byte(void)//?AHT20??????
{
		uint8_t Byte,i,a;
	Byte = 0;
	SCL_Pin_Output_Low();
	
	SDA_Pin_IN_FLOATING();
	SensorDelay_us(8);	
	
	for(i=0;i<8;i++)
	{
    SCL_Pin_Output_High();
		
		Delay_5us();
		a=0;
		
		//if(GPIO_ReadInputDataBit(GPIOB,GPIO_Pin_15)) a=1;
		if(HAL_GPIO_ReadPin(GPIOB,GPIO_PIN_7)) a=1;
		Byte = (Byte<<1)|a;
		
		//SCL_Pin_Output_Low();
		HAL_GPIO_WritePin(GPIOB,GPIO_PIN_6,GPIO_PIN_RESET);
		Delay_5us();
	}
  SDA_Pin_IN_FLOATING();
	SensorDelay_us(8);	
	return Byte;
}


uint8_t Receive_ACK(void)   //?AHT20?????ACK
{
	uint16_t CNT;
	CNT = 0;
	SCL_Pin_Output_Low();	
	SDA_Pin_IN_FLOATING();
	SensorDelay_us(8);	
	SCL_Pin_Output_High();	
	SensorDelay_us(8);	
	while((HAL_GPIO_ReadPin(GPIOB,GPIO_PIN_7))  && CNT < 100) 
	CNT++;
	if(CNT == 100)
	{
		return 0;
	}
 	SCL_Pin_Output_Low();	
	SensorDelay_us(8);	
	return 1;
}

void Send_ACK(void)		  //????ACK??
{
	SCL_Pin_Output_Low();	
	SensorDelay_us(8);	
	SDA_Pin_Output_Low();
	SensorDelay_us(8);	
	SCL_Pin_Output_High();	
	SensorDelay_us(8);
	SCL_Pin_Output_Low();	
	SensorDelay_us(8);
	SDA_Pin_IN_FLOATING();
	SensorDelay_us(8);
}

void Send_NOT_ACK(void)	//?????ACK
{
	SCL_Pin_Output_Low();	
	SensorDelay_us(8);
	SDA_Pin_Output_High();
	SensorDelay_us(8);
	SCL_Pin_Output_High();	
	SensorDelay_us(8);		
	SCL_Pin_Output_Low();	
	SensorDelay_us(8);
    SDA_Pin_Output_Low();
	SensorDelay_us(8);
}

void Stop_I2C(void)	  //??????
{
	SDA_Pin_Output_Low();
	SensorDelay_us(8);
	SCL_Pin_Output_High();	
	SensorDelay_us(8);
	SDA_Pin_Output_High();
	SensorDelay_us(8);
}

uint8_t AHT20_Read_Status(void)//??AHT20??????
{

	uint8_t Byte_first;	
	I2C_Start();
	AHT20_WR_Byte(0x71);
	Receive_ACK();
	Byte_first = AHT20_RD_Byte();
	Send_NOT_ACK();
	Stop_I2C();
	return Byte_first;
}

uint8_t AHT20_Read_Cal_Enable(void)  //??cal enable??????
{
	uint8_t val = 0;//ret = 0,
  val = AHT20_Read_Status();
	 if((val & 0x68)==0x08)
		 return 1;
   else  return 0;
 }

void AHT20_SendAC(void) //?AHT20??AC??
{

	I2C_Start();
	AHT20_WR_Byte(0x70);
	Receive_ACK();
	AHT20_WR_Byte(0xac);//0xAC????
	Receive_ACK();
	AHT20_WR_Byte(0x33);
	Receive_ACK();
	AHT20_WR_Byte(0x00);
	Receive_ACK();
	Stop_I2C();

}

//CRC????:CRC8/MAXIM
//???:X8+X5+X4+1
//Poly:0011 0001  0x31
//????????? 1000 1100 0x8c
//C????:
uint8_t Calc_CRC8(uint8_t *message,uint8_t Num)
{
	uint8_t i;
	uint8_t byte;
	uint8_t crc=0xFF;
  for(byte=0; byte<Num; byte++)
  {
    crc^=(message[byte]);
    for(i=8;i>0;--i)
    {
      if(crc&0x80) crc=(crc<<1)^0x31;
      else crc=(crc<<1);
    }
  }
        return crc;
}

void AHT20_Read_CTdata(uint32_t *ct) //??CRC??,????AHT20????????
{
		volatile uint8_t  Byte_1th=0;
	volatile uint8_t  Byte_2th=0;
	volatile uint8_t  Byte_3th=0;
	volatile uint8_t  Byte_4th=0;
	volatile uint8_t  Byte_5th=0;
	volatile uint8_t  Byte_6th=0;
	 uint32_t RetuData = 0;
	uint16_t cnt = 0;
	AHT20_SendAC();//?AHT10??AC??
	Delay_1ms(80);//??80ms??	
    cnt = 0;
	while(((AHT20_Read_Status()&0x80)==0x80))//????bit[7]?0,???????,??1,?????
	{
		SensorDelay_us(1508);
		if(cnt++>=100)
		{
		 break;
		 }
	}
	I2C_Start();
	AHT20_WR_Byte(0x71);
	Receive_ACK();
	Byte_1th = AHT20_RD_Byte();//???,??????0x98,??????,bit[7]?1;???0x1C,??0x0C,??0x08???????,bit[7]?0
	Send_ACK();
	Byte_2th = AHT20_RD_Byte();//??
	Send_ACK();
	Byte_3th = AHT20_RD_Byte();//??
	Send_ACK();
	Byte_4th = AHT20_RD_Byte();//??/??
	Send_ACK();
	Byte_5th = AHT20_RD_Byte();//??
	Send_ACK();
	Byte_6th = AHT20_RD_Byte();//??
	Send_NOT_ACK();
	Stop_I2C();

	RetuData = (RetuData|Byte_2th)<<8;
	RetuData = (RetuData|Byte_3th)<<8;
	RetuData = (RetuData|Byte_4th);
	RetuData =RetuData >>4;
	ct[0] = RetuData;//??
	RetuData = 0;
	RetuData = (RetuData|Byte_4th)<<8;
	RetuData = (RetuData|Byte_5th)<<8;
	RetuData = (RetuData|Byte_6th);
	RetuData = RetuData&0xfffff;
	ct[1] =RetuData; //??

}


void AHT20_Read_CTdata_crc(uint32_t *ct) //CRC???,??AHT20????????
{
		volatile uint8_t  Byte_1th=0;
	volatile uint8_t  Byte_2th=0;
	volatile uint8_t  Byte_3th=0;
	volatile uint8_t  Byte_4th=0;
	volatile uint8_t  Byte_5th=0;
	volatile uint8_t  Byte_6th=0;
	volatile uint8_t  Byte_7th=0;
	 uint32_t RetuData = 0;
	 uint16_t cnt = 0;
	// uint8_t  CRCDATA=0;
	 uint8_t  CTDATA[6]={0};//??CRC????
	
	AHT20_SendAC();//?AHT10??AC??
	Delay_1ms(80);//??80ms??	
    cnt = 0;
	while(((AHT20_Read_Status()&0x80)==0x80))//????bit[7]?0,???????,??1,?????
	{
		SensorDelay_us(1508);
		if(cnt++>=100)
		{
		 break;
		}
	}
	
	I2C_Start();

	AHT20_WR_Byte(0x71);
	Receive_ACK();
	CTDATA[0]=Byte_1th = AHT20_RD_Byte();//???,??????0x98,??????,bit[7]?1;???0x1C,??0x0C,??0x08???????,bit[7]?0
	Send_ACK();
	CTDATA[1]=Byte_2th = AHT20_RD_Byte();//??
	Send_ACK();
	CTDATA[2]=Byte_3th = AHT20_RD_Byte();//??
	Send_ACK();
	CTDATA[3]=Byte_4th = AHT20_RD_Byte();//??/??
	Send_ACK();
	CTDATA[4]=Byte_5th = AHT20_RD_Byte();//??
	Send_ACK();
	CTDATA[5]=Byte_6th = AHT20_RD_Byte();//??
	Send_ACK();
	Byte_7th = AHT20_RD_Byte();//CRC??
	Send_NOT_ACK();                           //??: ?????NAK
	Stop_I2C();
	
	if(Calc_CRC8(CTDATA,6)==Byte_7th)
	{
	RetuData = (RetuData|Byte_2th)<<8;
	RetuData = (RetuData|Byte_3th)<<8;
	RetuData = (RetuData|Byte_4th);
	RetuData =RetuData >>4;
	ct[0] = RetuData;//??
	RetuData = 0;
	RetuData = (RetuData|Byte_4th)<<8;
	RetuData = (RetuData|Byte_5th)<<8;
	RetuData = (RetuData|Byte_6th);
	RetuData = RetuData&0xfffff;
	ct[1] =RetuData; //??
		
	}
	else
	{
		ct[0]=0x00;
		ct[1]=0x00;//???????,????????????
	}//CRC??
}


void AHT20_Init(void)   //???AHT20
{	
	Init_I2C_Sensor_Port();
	I2C_Start();
	AHT20_WR_Byte(0x70);
	Receive_ACK();
	AHT20_WR_Byte(0xa8);//0xA8??NOR????
	Receive_ACK();
	AHT20_WR_Byte(0x00);
	Receive_ACK();
	AHT20_WR_Byte(0x00);
	Receive_ACK();
	Stop_I2C();

	Delay_1ms(10);//??10ms??

	I2C_Start();
	AHT20_WR_Byte(0x70);
	Receive_ACK();
	AHT20_WR_Byte(0xbe);//0xBE?????,AHT20???????0xBE,   AHT10???????0xE1
	Receive_ACK();
	AHT20_WR_Byte(0x08);//?????bit[3]?1,?????
	Receive_ACK();
	AHT20_WR_Byte(0x00);
	Receive_ACK();
	Stop_I2C();
	Delay_1ms(10);//??10ms??
}
void JH_Reset_REG(uint8_t addr)
{
	
	uint8_t Byte_first,Byte_second,Byte_third;
	I2C_Start();
	AHT20_WR_Byte(0x70);//???0x70
	Receive_ACK();
	AHT20_WR_Byte(addr);
	Receive_ACK();
	AHT20_WR_Byte(0x00);
	Receive_ACK();
	AHT20_WR_Byte(0x00);
	Receive_ACK();
	Stop_I2C();

	Delay_1ms(5);//??5ms??
	I2C_Start();
	AHT20_WR_Byte(0x71);//
	Receive_ACK();
	Byte_first = AHT20_RD_Byte();
	Send_ACK();
	Byte_second = AHT20_RD_Byte();
	Send_ACK();
	Byte_third = AHT20_RD_Byte();
	Send_NOT_ACK();
	Stop_I2C();
	
  Delay_1ms(10);//??10ms??
	I2C_Start();
	AHT20_WR_Byte(0x70);///
	Receive_ACK();
	AHT20_WR_Byte(0xB0|addr);//?????
	Receive_ACK();
	AHT20_WR_Byte(Byte_second);
	Receive_ACK();
	AHT20_WR_Byte(Byte_third);
	Receive_ACK();
	Stop_I2C();
	
	Byte_second=0x00;
	Byte_third =0x00;
}

void AHT20_Start_Init(void)
{
	JH_Reset_REG(0x1b);
	JH_Reset_REG(0x1c);
	JH_Reset_REG(0x1e);
}

AHT20.h代码：

#ifndef _AHT20_DEMO_
#define _AHT20_DEMO_

#include "main.h"  

void Delay_N10us(uint32_t t);//????
void SensorDelay_us(uint32_t t);//????
void Delay_4us(void);		//????
void Delay_5us(void);		//????
void Delay_1ms(uint32_t t);	
void AHT20_Clock_Init(void);		//????
void SDA_Pin_Output_High(void)  ; //?PB15????? , ???????, PB15??I2C?SDA
void SDA_Pin_Output_Low(void);  //?P15?????  ???????
void SDA_Pin_IN_FLOATING(void);  //SDA???????
void SCL_Pin_Output_High(void); //SCL?????,P14??I2C?SCL
void SCL_Pin_Output_Low(void); //SCL?????
void Init_I2C_Sensor_Port(void); //???I2C??,??????
void I2C_Start(void);		 //I2C????START??
void AHT20_WR_Byte(uint8_t Byte); //?AHT20?????
uint8_t AHT20_RD_Byte(void);//?AHT20??????
uint8_t Receive_ACK(void);   //?AHT20?????ACK
void Send_ACK(void)	;	  //????ACK??
void Send_NOT_ACK(void);	//?????ACK
void Stop_I2C(void);	  //??????
uint8_t AHT20_Read_Status(void);//??AHT20??????
uint8_t AHT20_Read_Cal_Enable(void);  //??cal enable??????
void AHT20_SendAC(void); //?AHT20??AC??
uint8_t Calc_CRC8(uint8_t *message,uint8_t Num);
void AHT20_Read_CTdata(uint32_t *ct); //??CRC??,????AHT20????????
void AHT20_Read_CTdata_crc(uint32_t *ct); //CRC???,??AHT20????????
void AHT20_Init(void);   //???AHT20
void JH_Reset_REG(uint8_t addr);///?????
void AHT20_Start_Init(void);///?????????????
#endif

main.c代码：

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; Copyright (c) 2021 STMicroelectronics.
  * All rights reserved.</center></h2>
  *
  * This software component is licensed by ST under BSD 3-Clause license,
  * the "License"; You may not use this file except in compliance with the
  * License. You may obtain a copy of the License at:
  *                        opensource.org/licenses/BSD-3-Clause
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "dma.h"
#include "i2c.h"
#include "usart.h"
#include "gpio.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */

#include<stdio.h>
#include "AHT20-21_DEMO_V1_3.h" 

void SystemClock_Config(void);


int fputc(int ch,FILE *f)
 
{
    HAL_UART_Transmit(&huart1,(uint8_t *)&ch,1,0xFFFF);    
		//µÈ´ý·¢ËÍ½áÊø	
		while(__HAL_UART_GET_FLAG(&huart1,UART_FLAG_TC)!=SET){
		}		

    return ch;
}



int main(void)
{
  /* USER CODE BEGIN 1 */
	uint32_t CT_data[2]={0,0};
	volatile int  c1,t1;
	
	Delay_1ms(500);

	HAL_Init();

	SystemClock_Config();

	MX_GPIO_Init();
	MX_DMA_Init();
	MX_USART1_UART_Init();
	
	//³õÊ¼>>¯AHT20
	AHT20_Init();
	Delay_1ms(500);

  while (1)
  { 
    /* USER CODE END WHILE */
		AHT20_Read_CTdata(CT_data);       //²>>¾¹ýCRCÐ£Ñé£¬Ö±½Ó¶ÁÈ¡AHT20µÄÎÂ¶ÈºÍÊª¶ÈÊý¾Ý    ÍÆ¼öÃ¿¸ô´óÓÚ1S¶ÁÒ>>´Î
		//AHT20_Read_CTdata_crc(CT_data);  //crcÐ£Ñéºó£¬¶ÁÈ¡AHT20µÄÎÂ¶ÈºÍÊª¶ÈÊý¾Ý 
	

		c1 = CT_data[0]*1000/1024/1024;  //¼ÆËãµÃµ½Êª¶ÈÖµc1£¨·Å´óÁË10±¶£©
		t1 = CT_data[1]*2000/1024/1024-500;//¼ÆËãµÃµ½ÎÂ¶ÈÖµt1£¨·Å´óÁË10±¶£©
		printf("ÕýÔÚ¼ì²â");
		HAL_Delay(100);
		printf(".");
		HAL_Delay(100);
		printf(".");
		HAL_Delay(100);
		printf(".");
		HAL_Delay(100);
		printf(".");
		HAL_Delay(100);
		printf(".");
		HAL_Delay(100);
		printf(".");
		HAL_Delay(100);
		printf(".");
		HAL_Delay(100);
		printf(".");
		HAL_Delay(100);
		printf(".");
		HAL_Delay(100);
		printf(".");
		printf("\r\n");
		HAL_Delay(1000);
		printf("ÎÂ¶È:%d%d.%d",t1/100,(t1/10)%10,t1%10);
		printf("Êª¶È:%d%d.%d",c1/100,(c1/10)%10,c1%10);
		printf("\r\n");
		printf("µÈ´ý");
		HAL_Delay(100);
		printf(".");
		HAL_Delay(100);
		printf(".");
		HAL_Delay(100);
		printf(".");
		HAL_Delay(100);
		printf(".");
		HAL_Delay(100);
		printf(".");
		HAL_Delay(100);
		printf(".");
		HAL_Delay(100);
		printf(".");
		HAL_Delay(100);
		printf(".");
		HAL_Delay(100);
		printf(".");
		HAL_Delay(100);
		printf(".");
		printf("\r\n");
		HAL_Delay(1000);
  /* USER CODE END 3 */
	}
}

/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }
  /** Initializes the CPU, AHB and APB buses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
  {
    Error_Handler();
  }
}

/* USER CODE BEGIN 4 */

/* USER CODE END 4 */

/**
  * @brief  This function is executed in case of error occurrence.
  * @retval None
  */
void Error_Handler(void)
{
  /* USER CODE BEGIN Error_Handler_Debug */
  /* User can add his own implementation to report the HAL error return state */
  __disable_irq();
  while (1)
  {
  }
  /* USER CODE END Error_Handler_Debug */
}

#ifdef  USE_FULL_ASSERT
/**
  * @brief  Reports the name of the source file and the source line number
  *         where the assert_param error has occurred.
  * @param  file: pointer to the source file name
  * @param  line: assert_param error line source number
  * @retval None
  */
void assert_failed(uint8_t *file, uint32_t line)
{
  /* USER CODE BEGIN 6 */
  /* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */

/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

3.实物图连接

注：VDD接5v.

4.实验效果

注：若串口为显示信息，可尝试将STlink拔掉后重新插入再打开串口。

项目代码：

STM32温湿度采集项目包和AHT20: 存放STM32温湿度采集的KEil项目包和AHT20代码

参考博客：

I2C总线通信协议及实操stm32通过I2C实现温湿度（AHT20）采集_stm32 aht20-CSDN博客

使用STM32F103完成基于I2C协议的AHT20温湿度传感器的数据采集-CSDN博客

I2C通信协议详解和通信流程分析_i2c协议-CSDN博客

软件I2C与硬件I2C的区别_软件i2c和硬件i2c-CSDN博客