Read temperature and humidity data through IIC protocol

1. Definition of I2C

“I2C” stands for “Inter-Integrated Circuit” and is a commonly used serial communication protocol used to transfer data between different integrated circuits. When using the I2C protocol, there are usually two main implementations, namely “software I2C” and “hardware I2C”.

1. Software I2C:

Software I2C is an implementation that simulates the I2C protocol on general-purpose input/output (GPIO) pins through programming. This method is usually used in embedded systems or microcontrollers that do not have hardware I2C controllers. Software I2C requires programming to control the state of the pins, including the high and low levels of the clock line (SCL) and data line (SDA), to simulate I2C communication. The advantage of this approach is that I2C communication can be implemented on almost any device with GPIO pins, but since it is simulated through software, there may be some timing and performance limitations.

2. Hardware I2C:

Hardware I2C refers to specialized I2C controllers built into the chip level. These controllers can automatically handle the timing and communication details in the I2C protocol without programmer intervention. Hardware I2C is generally more reliable and performs better because it is not interfered with by the operating system or other tasks. Hardware I2C is usually widely used in various integrated circuits such as microcontrollers, microcontrollers, sensors, displays, memories, etc.

2. Achieve results

1. Create a project through STM32CubeMX

Choose the chip we need (this article uses STM32F103C8T6)

Set up RCC:

Set up SYS:

Set up USART1:

Set GPIO:

Set the clock:

Set the pins:

Set up I2C1:

Set up NVIC:

Generate code:

2. Configure KEIL code

AHT20 chip code official website download: http://www.aosong.com/class-36-2.html
Baidu cloud download:
Link: https://pan.baidu.com/s/1prcoxve7ljS8ZS1QTvVFwQ
Extraction code: 1234
Create a new folder AHT in the corresponding file directory and copy the AHT20 chip code you just obtained into it.

Enter KEIL, add the folder AHT to the Group, and add the files in the newly created folder to it.

Then add the address of the newly created folder in Include Paths in C/C++

Then replace the following file codes respectively
AHT20-21_DEMO_V1_3.h

#ifndef _AHT20_DEMO_
#define _AHT20_DEMO_

#include "main.h"

void Delay_N10us(uint32_t t);//Delay function
void SensorDelay_us(uint32_t t);//Delay function
void Delay_4us(void); //Delay function
void Delay_5us(void); //Delay function
void Delay_1ms(uint32_t t);
void AHT20_Clock_Init(void); //Delay function
void SDA_Pin_Output_High(void); //Configure PB15 as output and set it to high level, PB15 serves as the SDA of I2C
void SDA_Pin_Output_Low(void); //Configure P15 as output and set to low level
void SDA_Pin_IN_FLOATING(void); //SDA is configured as floating input
void SCL_Pin_Output_High(void); //SCL outputs high level, P14 is used as I2C SCL
void SCL_Pin_Output_Low(void); //SCL output low level
void Init_I2C_Sensor_Port(void); //Initialize the I2C interface, the output is high level
void I2C_Start(void); //I2C host sends START signal
void AHT20_WR_Byte(uint8_t Byte); //Write a byte to AHT20
uint8_t AHT20_RD_Byte(void);//Read a byte from AHT20
uint8_t Receive_ACK(void); //See if AHT20 replies ACK
void Send_ACK(void); //The host replies with ACK signal
void Send_NOT_ACK(void); //The host does not reply ACK
void Stop_I2C(void); //End of a protocol
uint8_t AHT20_Read_Status(void);//Read the status register of AHT20
uint8_t AHT20_Read_Cal_Enable(void); //Check whether the cal enable bit is enabled
void AHT20_SendAC(void); //Send AC command to AHT20
uint8_t Calc_CRC8(uint8_t *message,uint8_t Num);
void AHT20_Read_CTdata(uint32_t *ct); //No CRC check, directly read the temperature and humidity data of AHT20
void AHT20_Read_CTdata_crc(uint32_t *ct); //After CRC verification, read the temperature and humidity data of AHT20
void AHT20_Init(void); //Initialize AHT20
void JH_Reset_REG(uint8_t addr);///Reset register
void AHT20_Start_Init(void);///Power-on initialization and enter the normal measurement state
#endif

AHT20-21_DEMO_V1_3.c

/************************************************/
/*@Copyright: Guangzhou Aosong Electronics Co., Ltd. */
/*@Author: Temperature and Humidity Sensor Division */
/*@Version: V1.2 */
/************************************************/
//#include "main.h"
#include "AHT20-21_DEMO_V1_3.h"
#include "gpio.h"
#include "i2c.h"


void Delay_N10us(uint32_t t)//delay function
{<!-- -->
  uint32_t k;

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

void SensorDelay_us(uint32_t t)//delay function
{<!-- -->
\t\t
for(t = t-2; t>0; t--)
{<!-- -->
Delay_N10us(1);
}
}

void Delay_4us(void) //Delay function
{<!-- -->
Delay_N10us(1);
Delay_N10us(1);
Delay_N10us(1);
Delay_N10us(1);
}
void Delay_5us(void) //Delay function
{<!-- -->
Delay_N10us(1);
Delay_N10us(1);
Delay_N10us(1);
Delay_N10us(1);
Delay_N10us(1);

}

void Delay_1ms(uint32_t t) //Delay function
{<!-- -->
   while(t--)
  {<!-- -->
    SensorDelay_us(1000);//Delay 1ms
  }
}


//void AHT20_Clock_Init(void) //Delay function
//{<!-- -->
// RCC_APB2PeriphClockCmd(CC_APB2Periph_GPIOB,ENABLE);
//}

void SDA_Pin_Output_High(void) //Configure PB7 as output and set to high level, PB7 serves as I2C SDA
{<!-- -->
GPIO_InitTypeDef GPIO_InitStruct;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;//Push-pull output
GPIO_InitStruct.Pin = GPIO_PIN_7;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
HAL_GPIO_Init(GPIOB, & amp; GPIO_InitStruct);
HAL_GPIO_WritePin(GPIOB,GPIO_PIN_7,GPIO_PIN_SET);
}

void SDA_Pin_Output_Low(void) //Configure P7 as output and set to low level
{<!-- -->
GPIO_InitTypeDef GPIO_InitStruct;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;//Push-pull output
GPIO_InitStruct.Pin = GPIO_PIN_7;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
HAL_GPIO_Init(GPIOB, & amp; GPIO_InitStruct);
HAL_GPIO_WritePin(GPIOB,GPIO_PIN_7,GPIO_PIN_RESET);
}

void SDA_Pin_IN_FLOATING(void) //SDA is configured as floating input
{<!-- -->
GPIO_InitTypeDef GPIO_InitStruct;
GPIO_InitStruct.Mode = GPIO_MODE_INPUT;//Float
GPIO_InitStruct.Pin = GPIO_PIN_7;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
HAL_GPIO_Init( GPIOB, & amp;GPIO_InitStruct);
}


void SCL_Pin_Output_High(void) //SCL outputs high level, P14 is used as I2C SCL
{<!-- -->
HAL_GPIO_WritePin(GPIOB,GPIO_PIN_6,GPIO_PIN_SET);
}

void SCL_Pin_Output_Low(void) //SCL output low level
{<!-- -->
HAL_GPIO_WritePin(GPIOB,GPIO_PIN_6,GPIO_PIN_RESET);
}

void Init_I2C_Sensor_Port(void) //Initialize the I2C interface, the output is high level
{<!-- -->
GPIO_InitTypeDef GPIO_InitStruct;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;//Push-pull output
GPIO_InitStruct.Pin = GPIO_PIN_7;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
HAL_GPIO_Init(GPIOB, & amp; GPIO_InitStruct);
HAL_GPIO_WritePin(GPIOB,GPIO_PIN_15,GPIO_PIN_SET);

\t
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;//Push-pull output
GPIO_InitStruct.Pin = GPIO_PIN_6;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
HAL_GPIO_Init(GPIOB, & amp; GPIO_InitStruct);
HAL_GPIO_WritePin(GPIOB,GPIO_PIN_15,GPIO_PIN_SET);
\t
}
void I2C_Start(void) //I2C host sends START signal
{<!-- -->
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) //Write a byte to 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();
}
\t\t\t
    SCL_Pin_Output_High();
Delay_4us();
Data <<= 1;
\t\t 
}
SCL_Pin_Output_Low();
SensorDelay_us(8);
SDA_Pin_IN_FLOATING();
SensorDelay_us(8);
}


uint8_t AHT20_RD_Byte(void)//Read a byte from AHT20
{<!-- -->
uint8_t Byte,i,a;
Byte = 0;
SCL_Pin_Output_Low();
\t
SDA_Pin_IN_FLOATING();
SensorDelay_us(8);
\t
for(i=0;i<8;i + + )
{<!-- -->
    SCL_Pin_Output_High();
\t\t
Delay_5us();
a=0;
\t\t
//if(GPIO_ReadInputDataBit(GPIOB,GPIO_Pin_15)) a=1;
if(HAL_GPIO_ReadPin(GPIOB,GPIO_PIN_7)) a=1;
Byte = (Byte<<1)|a;
\t\t
//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) //See if AHT20 replies 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)) & amp; & amp; CNT < 100)
CNT + + ;
if(CNT == 100)
{<!-- -->
return 0;
}
 SCL_Pin_Output_Low();
SensorDelay_us(8);
return 1;
}

void Send_ACK(void) //The host replies with ACK signal
{<!-- -->
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) //The host does not reply 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) //End of a protocol
{<!-- -->
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)//Read the status register of 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) //Check whether the cal enable bit is enabled
{<!-- -->
uint8_t val = 0;//ret = 0,
  val = AHT20_Read_Status();
if((val & amp; 0x68)==0x08)
return 1;
   else return 0;
 }

void AHT20_SendAC(void) //Send AC command to AHT20
{<!-- -->

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

}

//CRC check type: CRC8/MAXIM
//Polynomial: X8 + X5 + X4 + 1
//Poly: 0011 0001 0x31
//Put the high bit at the back and it becomes 1000 1100 0x8c
//C actual code:
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 & amp;0x80) crc=(crc<<1)^0x31;
      else crc=(crc<<1);
    }
  }
        return crc;
}

void AHT20_Read_CTdata(uint32_t *ct) //No CRC check, directly read the temperature and humidity data of 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();//Send AC command to AHT10
Delay_1ms(80);//The delay is about 80ms
    cnt = 0;
while(((AHT20_Read_Status() & amp;0x80)==0x80))//Until the status bit[7] is 0, it means the idle state, if it is 1, it means the busy state
{<!-- -->
SensorDelay_us(1508);
if(cnt + + >=100)
{<!-- -->
break;
}
}
I2C_Start();
AHT20_WR_Byte(0x71);
Receive_ACK();
Byte_1th = AHT20_RD_Byte();//Status word, the status is 0x98, which means busy state, bit[7] is 1; the status is 0x1C, or 0x0C, or 0x08, which means idle state, bit[7] is 0
Send_ACK();
Byte_2th = AHT20_RD_Byte();//Humidity
Send_ACK();
Byte_3th = AHT20_RD_Byte();//Humidity
Send_ACK();
Byte_4th = AHT20_RD_Byte();//humidity/temperature
Send_ACK();
Byte_5th = AHT20_RD_Byte();//Temperature
Send_ACK();
Byte_6th = AHT20_RD_Byte();//Temperature
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;//Humidity
RetuData = 0;
RetuData = (RetuData|Byte_4th)<<8;
RetuData = (RetuData|Byte_5th)<<8;
RetuData = (RetuData|Byte_6th);
RetuData = RetuData &0xfffff;
ct[1] =RetuData; //Temperature

}


void AHT20_Read_CTdata_crc(uint32_t *ct) //After CRC verification, read the temperature and humidity data of 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};//For CRC transfer array
\t
AHT20_SendAC();//Send AC command to AHT10
Delay_1ms(80);//The delay is about 80ms
    cnt = 0;
while(((AHT20_Read_Status() & amp;0x80)==0x80))//Until the status bit[7] is 0, it means the idle state, if it is 1, it means the busy state
{<!-- -->
SensorDelay_us(1508);
if(cnt + + >=100)
{<!-- -->
break;
}
}
\t
I2C_Start();

AHT20_WR_Byte(0x71);
Receive_ACK();
CTDATA[0]=Byte_1th = AHT20_RD_Byte();//Status word, the status is 0x98, which means busy state, bit[7] is 1; the status is 0x1C, or 0x0C, or 0x08, which means idle state, bit[ 7] is 0
Send_ACK();
CTDATA[1]=Byte_2th = AHT20_RD_Byte();//Humidity
Send_ACK();
CTDATA[2]=Byte_3th = AHT20_RD_Byte();//Humidity
Send_ACK();
CTDATA[3]=Byte_4th = AHT20_RD_Byte();//humidity/temperature
Send_ACK();
CTDATA[4]=Byte_5th = AHT20_RD_Byte();//Temperature
Send_ACK();
CTDATA[5]=Byte_6th = AHT20_RD_Byte();//Temperature
Send_ACK();
Byte_7th = AHT20_RD_Byte();//CRC data
Send_NOT_ACK(); //Note: NAK is sent at the end
Stop_I2C();
\t
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;//Humidity
RetuData = 0;
RetuData = (RetuData|Byte_4th)<<8;
RetuData = (RetuData|Byte_5th)<<8;
RetuData = (RetuData|Byte_6th);
RetuData = RetuData &0xfffff;
ct[1] =RetuData; //Temperature
\t\t
}
else
{<!-- -->
ct[0]=0x00;
ct[1]=0x00;//Verification error return value, customers can change it according to their needs
}//CRC data
}


void AHT20_Init(void) //Initialize AHT20
{<!-- -->
Init_I2C_Sensor_Port();
I2C_Start();
AHT20_WR_Byte(0x70);
Receive_ACK();
AHT20_WR_Byte(0xa8);//0xA8 enters NOR working mode
Receive_ACK();
AHT20_WR_Byte(0x00);
Receive_ACK();
AHT20_WR_Byte(0x00);
Receive_ACK();
Stop_I2C();

Delay_1ms(10);//Delay about 10ms

I2C_Start();
AHT20_WR_Byte(0x70);
Receive_ACK();
AHT20_WR_Byte(0xbe);//0xBE initialization command, the initialization command of AHT20 is 0xBE, the initialization command of AHT10 is 0xE1
Receive_ACK();
AHT20_WR_Byte(0x08);//Relevant register bit[3] is set to 1, which is the calibration output
Receive_ACK();
AHT20_WR_Byte(0x00);
Receive_ACK();
Stop_I2C();
Delay_1ms(10);//Delay about 10ms
}
void JH_Reset_REG(uint8_t addr)
{<!-- -->
\t
uint8_t Byte_first,Byte_second,Byte_third;
I2C_Start();
AHT20_WR_Byte(0x70);//originally 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);//The delay is about 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();
\t
  Delay_1ms(10);//Delay about 10ms
I2C_Start();
AHT20_WR_Byte(0x70);///
Receive_ACK();
AHT20_WR_Byte(0xB0|addr);//Register command
Receive_ACK();
AHT20_WR_Byte(Byte_second);
Receive_ACK();
AHT20_WR_Byte(Byte_third);
Receive_ACK();
Stop_I2C();
\t
Byte_second=0x00;
Byte_third =0x00;
}

void AHT20_Start_Init(void)
{<!-- -->
JH_Reset_REG(0x1b);
JH_Reset_REG(0x1c);
JH_Reset_REG(0x1e);
}

main.c

/* USER CODE BEGIN Header */
/**
  *************************************************** ****************************
  * @file: main.c
  * @brief: Main program body
  *************************************************** ****************************
  * @attention
  *
  * Copyright (c) 2022 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  *************************************************** ****************************
  */
/* 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"
/* USER CODE END Includes */

/* Private typedef ----------------------------------------------- -------------*/
/* USER CODE BEGIN PTD */


int fputc(int ch, FILE *f)
 
{<!-- -->
 
  HAL_UART_Transmit( & amp;huart1, (uint8_t *) & amp;ch, 1, 0xffff);
 
  return ch;
 
}

/* USER CODE END PTD */

/* Private define -------------------------------------------------- ---------------*/
/* USER CODE BEGIN PD */
/* USER CODE END PD */

/* Private macro ----------------------------------------------- ---------------*/
/* USER CODE BEGIN PM */

/* USER CODE END PM */

/* Private variables -------------------------------------------------- -----------*/

/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes ------------------------------------------------ --*/
void SystemClock_Config(void);
/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

/*Private user code--------------------------------------------- ----------*/
/* USER CODE BEGIN 0 */

/* USER CODE END 0 */

/**
  * @brief The application entry point.
  * @retval int
  */
int main(void)
{<!-- -->
  /* USER CODE BEGIN 1 */
uint32_t CT_data[2]={<!-- -->0,0};
volatile int c1,t1;
Delay_1ms(500);
  /* USER CODE END 1 */

  /* MCU Configuration------------------------------------------------- ----------*/

  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();

  /* USER CODE BEGIN Init */

  /* USER CODE END Init */

  /* Configure the system clock */
  SystemClock_Config();

  /* USER CODE BEGIN SysInit */

  /* USER CODE END SysInit */

  /* Initialize all configured peripherals */
  
  MX_USART1_UART_Init();
  MX_DMA_Init();
  MX_I2C1_Init();
  MX_USART1_UART_Init();
\t
  /* USER CODE BEGIN 2 */
  AHT20_Init();
Delay_1ms(500);

  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {<!-- -->
    /* USER CODE END WHILE */
//AHT20_Read_CTdata(CT_data); //Read the temperature and humidity data of AHT20 directly without CRC check. It is recommended to read it every more than 1S.
AHT20_Read_CTdata_crc(CT_data); //After crc verification, read the temperature and humidity data of AHT20
\t

c1 = CT_data[0]*1000/1024/1024; //Calculate the humidity value c1 (enlarged 10 times)
t1 = CT_data[1]*2000/1024/1024-500;//Calculate the temperature value t1 (enlarged 10 times)
printf("Detecting");
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\
");
HAL_Delay(1000);
printf("Temperature:%d%d.%d",t1/100,(t1/10),t1);
printf("Humidity:%d%d.%d",c1/100,(c1/10),c1);
printf("\r\
");
printf("wait");
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\
");
HAL_Delay(1000);
    /* USER CODE BEGIN 3 */
  }
  /* 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_HSE;
  RCC_OscInitStruct.HSEState = RCC_HSE_ON;
  RCC_OscInitStruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
  RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
  if (HAL_RCC_OscConfig( & amp;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_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig( & amp;RCC_ClkInitStruct, FLASH_LATENCY_2) != 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\
", file, line) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */

usart.c

/* USER CODE BEGIN Header */
/**
  *************************************************** ****************************
  * @file usart.c
  * @brief This file provides code for the configuration
  * of the USART instances.
  *************************************************** ****************************
  *@attention
  *
  * Copyright (c) 2023 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  *************************************************** ****************************
  */
/* USER CODE END Header */
/* Includes ----------------------------------------------- ------------------*/
#include "usart.h"
#include "stdio.h"

/* USER CODE BEGIN 0 */

/* USER CODE END 0 */

UART_HandleTypeDef huart1;

/* USART1 init function */

void MX_USART1_UART_Init(void)
{<!-- -->

  /* USER CODE BEGIN USART1_Init 0 */

  /* USER CODE END USART1_Init 0 */

  /* USER CODE BEGIN USART1_Init 1 */

  /* USER CODE END USART1_Init 1 */
  huart1.Instance = USART1;
  huart1.Init.BaudRate = 115200;
  huart1.Init.WordLength = UART_WORDLENGTH_8B;
  huart1.Init.StopBits = UART_STOPBITS_1;
  huart1.Init.Parity = UART_PARITY_NONE;
  huart1.Init.Mode = UART_MODE_TX_RX;
  huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart1.Init.OverSampling = UART_OVERSAMPLING_16;
  if (HAL_UART_Init( & amp;huart1) != HAL_OK)
  {<!-- -->
    Error_Handler();
  }
  /* USER CODE BEGIN USART1_Init 2 */

  /* USER CODE END USART1_Init 2 */

}

void HAL_UART_MspInit(UART_HandleTypeDef* uartHandle)
{<!-- -->

  GPIO_InitTypeDef GPIO_InitStruct = {<!-- -->0};
  if(uartHandle->Instance==USART1)
  {<!-- -->
  /* USER CODE BEGIN USART1_MspInit 0 */

  /* USER CODE END USART1_MspInit 0 */
    /* USART1 clock enable */
    __HAL_RCC_USART1_CLK_ENABLE();

    __HAL_RCC_GPIOA_CLK_ENABLE();
    /**USART1 GPIO Configuration
    PA9 ------> USART1_TX
    PA10 ------> USART1_RX
    */
    GPIO_InitStruct.Pin = GPIO_PIN_9;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

    GPIO_InitStruct.Pin = GPIO_PIN_10;
    GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

  /* USER CODE BEGIN USART1_MspInit 1 */

  /* USER CODE END USART1_MspInit 1 */
  }
}

void HAL_UART_MspDeInit(UART_HandleTypeDef* uartHandle)
{<!-- -->

  if(uartHandle->Instance==USART1)
  {<!-- -->
  /* USER CODE BEGIN USART1_MspDeInit 0 */

  /* USER CODE END USART1_MspDeInit 0 */
    /* Peripheral clock disable */
    __HAL_RCC_USART1_CLK_DISABLE();

    /**USART1 GPIO Configuration
    PA9 ------> USART1_TX
    PA10 ------> USART1_RX
    */
    HAL_GPIO_DeInit(GPIOA, GPIO_PIN_9|GPIO_PIN_10);

  /* USER CODE BEGIN USART1_MspDeInit 1 */

  /* USER CODE END USART1_MspDeInit 1 */
  }
}

/* USER CODE BEGIN 1 */

/* USER CODE END 1 */

Compile when finished