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1. Environment configuration
Software: Keil 5.31
mcuisp
wildfire serial debugging assistant
Hardware: STM32F103C8T6 core board
AHT20 temperature and humidity collector
2. I2C bus communication protocol
1. Introduction to I2C
The I2C communication protocol (Inter-Integrated Circuit) was developed by Philps. Because it has few pins, simple hardware implementation, and strong scalability, it does not require external transceiver devices such as USART and CAN. It is now widely used in Communication between multiple integrated circuits (ICs) in a system.
2. I2C physical layer
The physical connection of the I2C bus is very simple, consisting of SDA (serial data line), SCL (serial clock line) and pull-up resistors. The communication principle is to generate the signals required by the I2C bus protocol for data transmission by controlling the high and low level timing of the SCL and SDA lines. When the bus is idle, SCL and SDA are pulled high by the pull-up resistor Rp, so that both the SDA and SCL lines remain high.
The I2C communication method is half-duplex, and there is only one SDA line, which can only communicate in one direction at the same time. 485 is also half-duplex, and SPI and uart communication are full-duplex.
3. I2C protocol layer
The I2C bus has three types of signals in the process of transmitting data, which are: start signal, end signal and response signal.
Start signal : When SCL is high level, SDA jumps from high level to low level, and starts to transmit data.
End signal : When SCL is high level, SDA jumps from low level to high level, and the data transmission ends.
Response signal : After receiving 8bit data, the IC that receives data sends a specific low-level pulse to the IC that sends data, indicating that the data has been received. After the CPU sends a signal to the controlled unit, it waits for the controlled unit to send a response signal. After receiving the response signal, the CPU makes a judgment on whether to continue to transmit the signal according to the actual situation. If no response signal is received, it is judged that the controlled unit is faulty.
Among these signals, the start signal is required, and the end signal and the response signal are optional.
4. Software IIC and hardware IIC
IIC is divided into software IIC and hardware IIC
software IIC: software IIC communication refers to the IIC simulated by the two I/O ports of the microcontroller, using software to control the pin state to simulate the I2C communication waveform, and the software to simulate the working method of the register.
Directly use the CPU core to control the GPIO output high and low levels according to the requirements of the I2C protocol, thereby simulating I2C.
Use: When controlling the start signal of I2C, control the GPIO pin as the SCL line to output high level, and then control the GPIO pin as the SDA line to complete the switching from high level to low level during this period. Finally, control the SCL line to switch to low level, so that a standard I2C start signal is output.
**Hardware IIC:** A piece of hardware circuit, the hardware I2C corresponds to the I2C peripheral on the chip, and has a corresponding I2C driver circuit. The I2C pins used are also dedicated, and the hardware (firmware) I2C directly calls the internal registers for configuration .
Direct use of the hardware I2C peripheral in the STM32 chip.
Use: As long as the corresponding registers are configured, the peripheral will generate the timing of the standard serial port protocol. After initializing the I2C peripheral, you only need to set a certain register bit to 1, and then the peripheral will control the corresponding SCL and SDA lines to automatically generate the I2C start signal, without the need for the core to directly control the level of the pin.
The efficiency of hardware I2C is much higher than that of software, and software I2C has a more flexible interface because it is not limited by pins.
3. Realize the acquisition program of AHT20
1. Hardware connection
The above picture is the pin diagram of the template, please look carefully, otherwise it may damage the
SCL, GND, SDA, VCC of the module AHT20, corresponding to the B6, GND, B7, 5V of the i2c module connected to the stm32f103 guide. (GND and 5V can be any module, note that the serial port should also correspond to 5V)
2. Code implementation
Here, add code to the blank project of the firmware library version, and realize the following functions:
collect temperature and humidity data every 2 seconds, and send it to the host computer through the serial port
The main function main.c:
#include "delay.h"
#include "usart.h"
#include "bsp_i2c.h"
int main(void)
{
delay_init(); //ÑÓʱº¯Êý³õʼ»¯
uart_init(115200); //´®¿Ú³õʼ»¯Îª115200
IIC_Init();
while(1)
{
printf("¿ªÊ¼²âÁ¿£¬ÇëÉԵȣº");
read_AHT20_once();
delay_ms(1500);
}
}
Then put the following code files together with main.c
usart.c:
#include "sys.h"
#include "usart.h"
//STM32F103ºËÐÄ°åÀý³Ì
//¿âº¯Êý°æ±¾Àý³Ì
/********** mcudev.taobao.com ³öÆ· ********/
//
//Èç¹ûʹÓÃucos,Ôò°üÀ¨ÏÂÃæµÄÍ·Îļþ¼´¿É.
#if SYSTEM_SUPPORT_UCOS
#include "includes.h" //ucos ʹÓÃ
#endif
//
//STM32¿ª·¢°å
//´®¿Ú1³õʼ»¯
//
//
//¼ÓÈëÒÔÏ´úÂë,Ö§³Öprintfº¯Êý,¶ø²»ÐèҪѡÔñuse MicroLIB
#if 1
#pragma import(__use_no_semihosting)
//±ê×¼¿âÐèÒªµÄÖ§³Öº¯Êý
struct __FILE
{
int handle;
};
FILE __stdout;
//¶¨Òå_sys_exit()ÒÔ±ÜÃâʹÓðëÖ÷»úģʽ
void _sys_exit(int x)
{
x = x;
}
//Öض¨Òåfputcº¯Êý
int fputc(int ch, FILE *f)
{
while((USART1->SR&0X40)==0);//Ñ»··¢ËÍ,Ö±µ½·¢ËÍÍê±Ï
USART1->DR = (u8) ch;
return ch;
}
#endif
/*ʹÓÃmicroLibµÄ·½·¨*/
/*
int fputc(int ch, FILE *f)
{
USART_SendData(USART1, (uint8_t) ch);
while (USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET) {}
return ch;
}
int GetKey (void) {
while (!(USART1->SR & USART_FLAG_RXNE));
return ((int)(USART1->DR & 0x1FF));
}
*/
#if EN_USART1_RX //Èç¹ûʹÄÜÁ˽ÓÊÕ
//´®¿Ú1ÖжϷþÎñ³ÌÐò
//×¢Òâ,¶ÁÈ¡USARTx->SRÄܱÜÃâĪÃûÆäÃîµÄ´íÎó
u8 USART_RX_BUF[USART_REC_LEN]; //½ÓÊÕ»º³å,×î´óUSART_REC_LEN¸ö×Ö½Ú.
//½ÓÊÕ״̬
//bit15£¬ ½ÓÊÕÍê³É±êÖ¾
//bit14£¬ ½ÓÊÕµ½0x0d
//bit13~0£¬ ½ÓÊÕµ½µÄÓÐЧ×Ö½ÚÊýÄ¿
u16 USART_RX_STA=0; //½ÓÊÕ״̬±ê¼Ç
void uart_init(u32 bound){
//GPIO¶Ë¿ÚÉèÖÃ
GPIO_InitTypeDef GPIO_InitStructure;
USART_InitTypeDef USART_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1|RCC_APB2Periph_GPIOA, ENABLE); //ʹÄÜUSART1£¬GPIOAʱÖÓ
//USART1_TX PA.9
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9; //PA.9
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; //¸´ÓÃÍÆÍìÊä³ö
GPIO_Init(GPIOA, &GPIO_InitStructure);
//USART1_RX PA.10
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;//¸¡¿ÕÊäÈë
GPIO_Init(GPIOA, &GPIO_InitStructure);
//Usart1 NVIC ÅäÖÃ
NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=3 ;//ÇÀÕ¼ÓÅÏȼ¶3
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3; //×ÓÓÅÏȼ¶3
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQͨµÀʹÄÜ
NVIC_Init(&NVIC_InitStructure); //¸ù¾ÝÖ¸¶¨µÄ²ÎÊý³õʼ»¯VIC¼Ä´æÆ÷
//USART ³õʼ»¯ÉèÖÃ
USART_InitStructure.USART_BaudRate = bound;//Ò»°ãÉèÖÃΪ9600;
USART_InitStructure.USART_WordLength = USART_WordLength_8b;//×Ö³¤Îª8λÊý¾Ý¸ñʽ
USART_InitStructure.USART_StopBits = USART_StopBits_1;//Ò»¸öֹͣλ
USART_InitStructure.USART_Parity = USART_Parity_No;//ÎÞÆæżУÑéλ
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;//ÎÞÓ²¼þÊý¾ÝÁ÷¿ØÖÆ
USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx; //ÊÕ·¢Ä£Ê½
USART_Init(USART1, &USART_InitStructure); //³õʼ»¯´®¿Ú
USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);//¿ªÆôÖжÏ
USART_Cmd(USART1, ENABLE); //ʹÄÜ´®¿Ú
}
void USART1_IRQHandler(void) //´®¿Ú1ÖжϷþÎñ³ÌÐò
{
u8 Res;
#ifdef OS_TICKS_PER_SEC //Èç¹ûʱÖÓ½ÚÅÄÊý¶¨ÒåÁË,˵Ã÷ҪʹÓÃucosIIÁË.
OSIntEnter();
#endif
if(USART_GetITStatus(USART1, USART_IT_RXNE) != RESET) //½ÓÊÕÖжÏ(½ÓÊÕµ½µÄÊý¾Ý±ØÐëÊÇ0x0d 0x0a½áβ)
{
Res =USART_ReceiveData(USART1);//(USART1->DR); //¶ÁÈ¡½ÓÊÕµ½µÄÊý¾Ý
if((USART_RX_STA&0x8000)==0)//½ÓÊÕδÍê³É
{
if(USART_RX_STA&0x4000)//½ÓÊÕµ½ÁË0x0d
{
if(Res!=0x0a)USART_RX_STA=0;//½ÓÊÕ´íÎó,ÖØпªÊ¼
else USART_RX_STA|=0x8000; //½ÓÊÕÍê³ÉÁË
}
else //»¹Ã»ÊÕµ½0X0D
{
if(Res==0x0d)USART_RX_STA|=0x4000;
else
{
USART_RX_BUF[USART_RX_STA&0X3FFF]=Res ;
USART_RX_STA++;
if(USART_RX_STA>(USART_REC_LEN-1))USART_RX_STA=0;//½ÓÊÕÊý¾Ý´íÎó,ÖØпªÊ¼½ÓÊÕ
}
}
}
}
#ifdef OS_TICKS_PER_SEC //Èç¹ûʱÖÓ½ÚÅÄÊý¶¨ÒåÁË,˵Ã÷ҪʹÓÃucosIIÁË.
OSIntExit();
#endif
}
#endif
usart.h：
#ifndef __USART_H
#define __USART_H
#include "stdio.h"
#include "sys.h"
//STM32F103ºËÐÄ°åÀý³Ì
//¿âº¯Êý°æ±¾Àý³Ì
/********** mcudev.taobao.com ³öÆ· ********/
//
//STM32¿ª·¢°å
//´®¿Ú1³õʼ»¯
#define USART_REC_LEN 200 //¶¨Òå×î´ó½ÓÊÕ×Ö½ÚÊý 200
#define EN_USART1_RX 1 //ʹÄÜ£¨1£©/½ûÖ¹£¨0£©´®¿Ú1½ÓÊÕ
extern u8 USART_RX_BUF[USART_REC_LEN]; //½ÓÊÕ»º³å,×î´óUSART_REC_LEN¸ö×Ö½Ú.Ä©×Ö½ÚΪ»»Ðзû
extern u16 USART_RX_STA; //½ÓÊÕ״̬±ê¼Ç
//Èç¹ûÏë´®¿ÚÖжϽÓÊÕ£¬Ç벻ҪעÊÍÒÔϺ궨Òå
void uart_init(u32 bound);
#endif
bsp_i2c.c：
#include "bsp_i2c.h"
#include "delay.h"
uint8_t ack_status=0;
uint8_t readByte[6];
uint8_t AHT20_status=0;
uint32_t H1=0; //Humility
uint32_t T1=0; //Temperature
uint8_t AHT20_OutData[4];
uint8_t AHT20sendOutData[10] = {
0xFA, 0x06, 0x0A, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF};
void IIC_Init(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
RCC_APB2PeriphClockCmd( RCC_APB2Periph_GPIOB, ENABLE );
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6|GPIO_Pin_7;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP ; //ÍÆÍìÊä³ö
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOB, &GPIO_InitStructure);
IIC_SCL=1;
IIC_SDA=1;
}
//²úÉúIICÆðʼÐźÅ
void IIC_Start(void)
{
SDA_OUT(); //sdaÏßÊä³ö
IIC_SDA=1;
IIC_SCL=1;
delay_us(4);
IIC_SDA=0;//START:when CLK is high,DATA change form high to low
delay_us(4);
IIC_SCL=0;//ǯסI2C×ÜÏߣ¬×¼±¸·¢ËÍ»ò½ÓÊÕÊý¾Ý
}
//²úÉúIICÍ£Ö¹ÐźÅ
void IIC_Stop(void)
{
SDA_OUT();//sdaÏßÊä³ö
IIC_SCL=0;
IIC_SDA=0;//STOP:when CLK is high DATA change form low to high
delay_us(4);
IIC_SCL=1;
IIC_SDA=1;//·¢ËÍI2C×ÜÏß½áÊøÐźÅ
delay_us(4);
}
//µÈ´ýÓ¦´ðÐźŵ½À´
//·µ»ØÖµ£º1£¬½ÓÊÕÓ¦´ðʧ°Ü
// 0£¬½ÓÊÕÓ¦´ð³É¹¦
u8 IIC_Wait_Ack(void)
{
u8 ucErrTime=0;
SDA_IN(); //SDAÉèÖÃΪÊäÈë
IIC_SDA=1;delay_us(1);
IIC_SCL=1;delay_us(1);
while(READ_SDA)
{
ucErrTime++;
if(ucErrTime>250)
{
IIC_Stop();
return 1;
}
}
IIC_SCL=0;//ʱÖÓÊä³ö0
return 0;
}
//²úÉúACKÓ¦´ð
void IIC_Ack(void)
{
IIC_SCL=0;
SDA_OUT();
IIC_SDA=0;
delay_us(2);
IIC_SCL=1;
delay_us(2);
IIC_SCL=0;
}
//²»²úÉúACKÓ¦´ð
void IIC_NAck(void)
{
IIC_SCL=0;
SDA_OUT();
IIC_SDA=1;
delay_us(2);
IIC_SCL=1;
delay_us(2);
IIC_SCL=0;
}
//IIC·¢ËÍÒ»¸ö×Ö½Ú
//·µ»Ø´Ó»úÓÐÎÞÓ¦´ð
//1£¬ÓÐÓ¦´ð
//0£¬ÎÞÓ¦´ð
void IIC_Send_Byte(u8 txd)
{
u8 t;
SDA_OUT();
IIC_SCL=0;//ÀµÍʱÖÓ¿ªÊ¼Êý¾Ý´«Êä
for(t=0;t<8;t++)
{
IIC_SDA=(txd&0x80)>>7;
txd<<=1;
delay_us(2); //¶ÔTEA5767ÕâÈý¸öÑÓʱ¶¼ÊDZØÐëµÄ
IIC_SCL=1;
delay_us(2);
IIC_SCL=0;
delay_us(2);
}
}
//¶Á1¸ö×Ö½Ú£¬ack=1ʱ£¬·¢ËÍACK£¬ack=0£¬·¢ËÍnACK
u8 IIC_Read_Byte(unsigned char ack)
{
unsigned char i,receive=0;
SDA_IN();//SDAÉèÖÃΪÊäÈë
for(i=0;i<8;i++ )
{
IIC_SCL=0;
delay_us(2);
IIC_SCL=1;
receive<<=1;
if(READ_SDA)receive++;
delay_us(1);
}
if (!ack)
IIC_NAck();//·¢ËÍnACK
else
IIC_Ack(); //·¢ËÍACK
return receive;
}
void IIC_WriteByte(uint16_t addr,uint8_t data,uint8_t device_addr)
{
IIC_Start();
if(device_addr==0xA0) //eepromµØÖ·´óÓÚ1×Ö½Ú
IIC_Send_Byte(0xA0 + ((addr/256)<<1));//·¢Ë͸ߵØÖ·
else
IIC_Send_Byte(device_addr); //·¢Æ÷¼þµØÖ·
IIC_Wait_Ack();
IIC_Send_Byte(addr&0xFF); //·¢Ë͵͵ØÖ·
IIC_Wait_Ack();
IIC_Send_Byte(data); //·¢ËÍ×Ö½Ú
IIC_Wait_Ack();
IIC_Stop();//²úÉúÒ»¸öÍ£Ö¹Ìõ¼þ
if(device_addr==0xA0) //
delay_ms(10);
else
delay_us(2);
}
uint16_t IIC_ReadByte(uint16_t addr,uint8_t device_addr,uint8_t ByteNumToRead) //¶Á¼Ä´æÆ÷»ò¶ÁÊý¾Ý
{
uint16_t data;
IIC_Start();
if(device_addr==0xA0)
IIC_Send_Byte(0xA0 + ((addr/256)<<1));
else
IIC_Send_Byte(device_addr);
IIC_Wait_Ack();
IIC_Send_Byte(addr&0xFF); //·¢Ë͵͵ØÖ·
IIC_Wait_Ack();
IIC_Start();
IIC_Send_Byte(device_addr+1); //·¢Æ÷¼þµØÖ·
IIC_Wait_Ack();
if(ByteNumToRead == 1)//LM75ζÈÊý¾ÝΪ11bit
{
data=IIC_Read_Byte(0);
}
else
{
data=IIC_Read_Byte(1);
data=(data<<8)+IIC_Read_Byte(0);
}
IIC_Stop();//²úÉúÒ»¸öÍ£Ö¹Ìõ¼þ
return data;
}
/**********
*ÉÏÃ沿·ÖΪIO¿ÚÄ£¿éI2CÅäÖÃ
*
*´ÓÕâÒÔÏ¿ªÊ¼ÎªAHT20µÄÅäÖÃI2C
*º¯ÊýÃûÓÐIICºÍI2CµÄÇø±ð£¬Çë×¢Ò⣡£¡£¡£¡£¡
*
*2020/2/23×îºóÐÞ¸ÄÈÕÆÚ
*
***********/
void read_AHT20_once(void)
{
delay_ms(10);
reset_AHT20();
delay_ms(10);
init_AHT20();
delay_ms(10);
startMeasure_AHT20();
delay_ms(80);
read_AHT20();
delay_ms(5);
}
void reset_AHT20(void)
{
I2C_Start();
I2C_WriteByte(0x70);
ack_status = Receive_ACK();
if(ack_status) printf("1");
else printf("1-n-");
I2C_WriteByte(0xBA);
ack_status = Receive_ACK();
if(ack_status) printf("2");
else printf("2-n-");
I2C_Stop();
/*
AHT20_OutData[0] = 0;
AHT20_OutData[1] = 0;
AHT20_OutData[2] = 0;
AHT20_OutData[3] = 0;
*/
}
void init_AHT20(void)
{
I2C_Start();
I2C_WriteByte(0x70);
ack_status = Receive_ACK();
if(ack_status) printf("3");
else printf("3-n-");
I2C_WriteByte(0xE1);
ack_status = Receive_ACK();
if(ack_status) printf("4");
else printf("4-n-");
I2C_WriteByte(0x08);
ack_status = Receive_ACK();
if(ack_status) printf("5");
else printf("5-n-");
I2C_WriteByte(0x00);
ack_status = Receive_ACK();
if(ack_status) printf("6");
else printf("6-n-");
I2C_Stop();
}
void startMeasure_AHT20(void)
{
//------------
I2C_Start();
I2C_WriteByte(0x70);
ack_status = Receive_ACK();
if(ack_status) printf("7");
else printf("7-n-");
I2C_WriteByte(0xAC);
ack_status = Receive_ACK();
if(ack_status) printf("8");
else printf("8-n-");
I2C_WriteByte(0x33);
ack_status = Receive_ACK();
if(ack_status) printf("9");
else printf("9-n-");
I2C_WriteByte(0x00);
ack_status = Receive_ACK();
if(ack_status) printf("10");
else printf("10-n-");
I2C_Stop();
}
void read_AHT20(void)
{
uint8_t i;
for(i=0; i<6; i++)
{
readByte[i]=0;
}
//-------------
I2C_Start();
I2C_WriteByte(0x71);
ack_status = Receive_ACK();
readByte[0]= I2C_ReadByte();
Send_ACK();
readByte[1]= I2C_ReadByte();
Send_ACK();
readByte[2]= I2C_ReadByte();
Send_ACK();
readByte[3]= I2C_ReadByte();
Send_ACK();
readByte[4]= I2C_ReadByte();
Send_ACK();
readByte[5]= I2C_ReadByte();
SendNot_Ack();
//Send_ACK();
I2C_Stop();
//--------------
if( (readByte[0] & 0x68) == 0x08 )
{
H1 = readByte[1];
H1 = (H1<<8) | readByte[2];
H1 = (H1<<8) | readByte[3];
H1 = H1>>4;
H1 = (H1*1000)/1024/1024;
T1 = readByte[3];
T1 = T1 & 0x0000000F;
T1 = (T1<<8) | readByte[4];
T1 = (T1<<8) | readByte[5];
T1 = (T1*2000)/1024/1024 - 500;
AHT20_OutData[0] = (H1>>8) & 0x000000FF;
AHT20_OutData[1] = H1 & 0x000000FF;
AHT20_OutData[2] = (T1>>8) & 0x000000FF;
AHT20_OutData[3] = T1 & 0x000000FF;
}
else
{
AHT20_OutData[0] = 0xFF;
AHT20_OutData[1] = 0xFF;
AHT20_OutData[2] = 0xFF;
AHT20_OutData[3] = 0xFF;
printf("ʧ°ÜÁË");
}
printf("\r\n");
printf("ζÈ:%d%d.%d",T1/100,(T1/10)%10,T1%10);
printf("ʪ¶È:%d%d.%d",H1/100,(H1/10)%10,H1%10);
printf("\r\n");
}
uint8_t Receive_ACK(void)
{
uint8_t result=0;
uint8_t cnt=0;
IIC_SCL = 0;
SDA_IN();
delay_us(4);
IIC_SCL = 1;
delay_us(4);
while(READ_SDA && (cnt<100))
{
cnt++;
}
IIC_SCL = 0;
delay_us(4);
if(cnt<100)
{
result=1;
}
return result;
}
void Send_ACK(void)
{
SDA_OUT();
IIC_SCL = 0;
delay_us(4);
IIC_SDA = 0;
delay_us(4);
IIC_SCL = 1;
delay_us(4);
IIC_SCL = 0;
delay_us(4);
SDA_IN();
}
void SendNot_Ack(void)
{
SDA_OUT();
IIC_SCL = 0;
delay_us(4);
IIC_SDA = 1;
delay_us(4);
IIC_SCL = 1;
delay_us(4);
IIC_SCL = 0;
delay_us(4);
IIC_SDA = 0;
delay_us(4);
}
void I2C_WriteByte(uint8_t input)
{
uint8_t i;
SDA_OUT();
for(i=0; i<8; i++)
{
IIC_SCL = 0;
delay_ms(5);
if(input & 0x80)
{
IIC_SDA = 1;
//delaymm(10);
}
else
{
IIC_SDA = 0;
//delaymm(10);
}
IIC_SCL = 1;
delay_ms(5);
input = (input<<1);
}
IIC_SCL = 0;
delay_us(4);
SDA_IN();
delay_us(4);
}
uint8_t I2C_ReadByte(void)
{
uint8_t resultByte=0;
uint8_t i=0, a=0;
IIC_SCL = 0;
SDA_IN();
delay_ms(4);
for(i=0; i<8; i++)
{
IIC_SCL = 1;
delay_ms(3);
a=0;
if(READ_SDA)
{
a=1;
}
else
{
a=0;
}
//resultByte = resultByte | a;
resultByte = (resultByte << 1) | a;
IIC_SCL = 0;
delay_ms(3);
}
SDA_IN();
delay_ms(10);
return resultByte;
}
void set_AHT20sendOutData(void)
{
/* --------------------------
* 0xFA 0x06 0x0A temperature(2 Bytes) humility(2Bytes) short Address(2 Bytes)
* And Check (1 byte)
* -------------------------*/
AHT20sendOutData[3] = AHT20_OutData[0];
AHT20sendOutData[4] = AHT20_OutData[1];
AHT20sendOutData[5] = AHT20_OutData[2];
AHT20sendOutData[6] = AHT20_OutData[3];
// AHT20sendOutData[7] = (drf1609.shortAddress >> 8) & 0x00FF;
// AHT20sendOutData[8] = drf1609.shortAddress & 0x00FF;
// AHT20sendOutData[9] = getXY(AHT20sendOutData,10);
}
void I2C_Start(void)
{
SDA_OUT();
IIC_SCL = 1;
delay_ms(4);
IIC_SDA = 1;
delay_ms(4);
IIC_SDA = 0;
delay_ms(4);
IIC_SCL = 0;
delay_ms(4);
}
void I2C_Stop(void)
{
SDA_OUT();
IIC_SDA = 0;
delay_ms(4);
IIC_SCL = 1;
delay_ms(4);
IIC_SDA = 1;
delay_ms(4);
}
bsp_i2c.h：
#ifndef __BSP_I2C_H
#define __BSP_I2C_H
#include "sys.h"
#include "delay.h"
#include "usart.h"
//ʹÓÃIIC1 ¹ÒÔØM24C02,OLED,LM75AD,HT1382 PB6,PB7
#define SDA_IN() {
GPIOB->CRL&=0X0FFFFFFF;GPIOB->CRL|=(u32)8<<28;}
#define SDA_OUT() {
GPIOB->CRL&=0X0FFFFFFF;GPIOB->CRL|=(u32)3<<28;}
//IO²Ù×÷º¯Êý
#define IIC_SCL PBout(6) //SCL
#define IIC_SDA PBout(7) //SDA
#define READ_SDA PBin(7) //ÊäÈëSDA
//IICËùÓвÙ×÷º¯Êý
void IIC_Init(void); //³õʼ»¯IICµÄIO¿Ú
void IIC_Start(void); //·¢ËÍIIC¿ªÊ¼ÐźÅ
void IIC_Stop(void); //·¢ËÍIICÍ£Ö¹ÐźÅ
void IIC_Send_Byte(u8 txd); //IIC·¢ËÍÒ»¸ö×Ö½Ú
u8 IIC_Read_Byte(unsigned char ack);//IIC¶ÁÈ¡Ò»¸ö×Ö½Ú
u8 IIC_Wait_Ack(void); //IICµÈ´ýACKÐźÅ
void IIC_Ack(void); //IIC·¢ËÍACKÐźÅ
void IIC_NAck(void); //IIC²»·¢ËÍACKÐźÅ
void IIC_WriteByte(uint16_t addr,uint8_t data,uint8_t device_addr);
uint16_t IIC_ReadByte(uint16_t addr,uint8_t device_addr,uint8_t ByteNumToRead);//¼Ä´æÆ÷µØÖ·£¬Æ÷¼þµØÖ·£¬Òª¶ÁµÄ×Ö½ÚÊý
void read_AHT20_once(void);
void reset_AHT20(void);
void init_AHT20(void);
void startMeasure_AHT20(void);
void read_AHT20(void);
uint8_t Receive_ACK(void);
void Send_ACK(void);
void SendNot_Ack(void);
void I2C_WriteByte(uint8_t input);
uint8_t I2C_ReadByte(void);
void set_AHT20sendOutData(void);
void I2C_Start(void);
void I2C_Stop(void);
#endif
delay.c：
#include "delay.h"
#include "sys.h"
//STM32F103ºËÐÄ°åÀý³Ì
//¿âº¯Êý°æ±¾Àý³Ì
/********** mcudev.taobao.com ³öÆ· ********/
//
//Èç¹ûʹÓÃucos,Ôò°üÀ¨ÏÂÃæµÄÍ·Îļþ¼´¿É.
#if SYSTEM_SUPPORT_UCOS
#include "includes.h" //ucos ʹÓÃ
#endif
//
//STM32¿ª·¢°å
//ʹÓÃSysTickµÄÆÕͨ¼ÆÊýģʽ¶ÔÑÓ³Ù½øÐйÜÀí
//°üÀ¨delay_us,delay_ms
//
static u8 fac_us=0;//usÑÓʱ±¶³ËÊý
static u16 fac_ms=0;//msÑÓʱ±¶³ËÊý
#ifdef OS_CRITICAL_METHOD //Èç¹ûOS_CRITICAL_METHOD¶¨ÒåÁË,˵Ã÷ʹÓÃucosIIÁË.
//systickÖжϷþÎñº¯Êý,ʹÓÃucosʱÓõ½
void SysTick_Handler(void)
{
OSIntEnter(); //½øÈëÖжÏ
OSTimeTick(); //µ÷ÓÃucosµÄʱÖÓ·þÎñ³ÌÐò
OSIntExit(); //´¥·¢ÈÎÎñÇл»ÈíÖжÏ
}
#endif
//³õʼ»¯ÑÓ³Ùº¯Êý
//µ±Ê¹ÓÃucosµÄʱºò,´Ëº¯Êý»á³õʼ»¯ucosµÄʱÖÓ½ÚÅÄ
//SYSTICKµÄʱÖӹ̶¨ÎªHCLKʱÖÓµÄ1/8
//SYSCLK:ϵͳʱÖÓ
void delay_init()
{
#ifdef OS_CRITICAL_METHOD //Èç¹ûOS_CRITICAL_METHOD¶¨ÒåÁË,˵Ã÷ʹÓÃucosIIÁË.
u32 reload;
#endif
SysTick_CLKSourceConfig(SysTick_CLKSource_HCLK_Div8); //Ñ¡ÔñÍⲿʱÖÓ HCLK/8
fac_us=SystemCoreClock/8000000; //ΪϵͳʱÖÓµÄ1/8
#ifdef OS_CRITICAL_METHOD //Èç¹ûOS_CRITICAL_METHOD¶¨ÒåÁË,˵Ã÷ʹÓÃucosIIÁË.
reload=SystemCoreClock/8000000; //ÿÃëÖӵļÆÊý´ÎÊý µ¥Î»ÎªK
reload*=1000000/OS_TICKS_PER_SEC;//¸ù¾ÝOS_TICKS_PER_SECÉ趨Òç³öʱ¼ä
//reloadΪ24λ¼Ä´æÆ÷,×î´óÖµ:16777216,ÔÚ72MÏÂ,Ô¼ºÏ1.86s×óÓÒ
fac_ms=1000/OS_TICKS_PER_SEC;//´ú±íucos¿ÉÒÔÑÓʱµÄ×îÉÙµ¥Î»
SysTick->CTRL|=SysTick_CTRL_TICKINT_Msk; //¿ªÆôSYSTICKÖжÏ
SysTick->LOAD=reload; //ÿ1/OS_TICKS_PER_SECÃëÖжÏÒ»´Î
SysTick->CTRL|=SysTick_CTRL_ENABLE_Msk; //¿ªÆôSYSTICK
#else
fac_ms=(u16)fac_us*1000;//·ÇucosÏÂ,´ú±íÿ¸ömsÐèÒªµÄsystickʱÖÓÊý
#endif
}
#ifdef OS_CRITICAL_METHOD //ʹÓÃÁËucos
//ÑÓʱnus
//nusΪҪÑÓʱµÄusÊý.
void delay_us(u32 nus)
{
u32 ticks;
u32 told,tnow,tcnt=0;
u32 reload=SysTick->LOAD; //LOADµÄÖµ
ticks=nus*fac_us; //ÐèÒªµÄ½ÚÅÄÊý
tcnt=0;
told=SysTick->VAL; //¸Õ½øÈëʱµÄ¼ÆÊýÆ÷Öµ
while(1)
{
tnow=SysTick->VAL;
if(tnow!=told)
{
if(tnow<told)tcnt+=told-tnow;//ÕâÀï×¢ÒâÒ»ÏÂSYSTICKÊÇÒ»¸öµÝ¼õµÄ¼ÆÊýÆ÷¾Í¿ÉÒÔÁË.
else tcnt+=reload-tnow+told;
told=tnow;
if(tcnt>=ticks)break;//ʱ¼ä³¬¹ý/µÈÓÚÒªÑÓ³ÙµÄʱ¼ä,ÔòÍ˳ö.
}
};
}
//ÑÓʱnms
//nms:ÒªÑÓʱµÄmsÊý
void delay_ms(u16 nms)
{
if(OSRunning==TRUE)//Èç¹ûosÒѾÔÚÅÜÁË
{
if(nms>=fac_ms)//ÑÓʱµÄʱ¼ä´óÓÚucosµÄ×îÉÙʱ¼äÖÜÆÚ
{
OSTimeDly(nms/fac_ms);//ucosÑÓʱ
}
nms%=fac_ms; //ucosÒѾÎÞ·¨ÌṩÕâôСµÄÑÓʱÁË,²ÉÓÃÆÕͨ·½Ê½ÑÓʱ
}
delay_us((u32)(nms*1000)); //ÆÕͨ·½Ê½ÑÓʱ,´ËʱucosÎÞ·¨Æô¶¯µ÷¶È.
}
#else//²»ÓÃucosʱ
//ÑÓʱnus
//nusΪҪÑÓʱµÄusÊý.
void delay_us(u32 nus)
{
u32 temp;
SysTick->LOAD=nus*fac_us; //ʱ¼ä¼ÓÔØ
SysTick->VAL=0x00; //Çå¿Õ¼ÆÊýÆ÷
SysTick->CTRL|=SysTick_CTRL_ENABLE_Msk ; //¿ªÊ¼µ¹Êý
do
{
temp=SysTick->CTRL;
}
while(temp&0x01&&!(temp&(1<<16)));//µÈ´ýʱ¼äµ½´ï
SysTick->CTRL&=~SysTick_CTRL_ENABLE_Msk; //¹Ø±Õ¼ÆÊýÆ÷
SysTick->VAL =0X00; //Çå¿Õ¼ÆÊýÆ÷
}
//ÑÓʱnms
//×¢ÒânmsµÄ·¶Î§
//SysTick->LOADΪ24λ¼Ä´æÆ÷,ËùÒÔ,×î´óÑÓʱΪ:
//nms<=0xffffff*8*1000/SYSCLK
//SYSCLKµ¥Î»ÎªHz,nmsµ¥Î»Îªms
//¶Ô72MÌõ¼þÏÂ,nms<=1864
void delay_ms(u16 nms)
{
u32 temp;
SysTick->LOAD=(u32)nms*fac_ms;//ʱ¼ä¼ÓÔØ(SysTick->LOADΪ24bit)
SysTick->VAL =0x00; //Çå¿Õ¼ÆÊýÆ÷
SysTick->CTRL|=SysTick_CTRL_ENABLE_Msk ; //¿ªÊ¼µ¹Êý
do
{
temp=SysTick->CTRL;
}
while(temp&0x01&&!(temp&(1<<16)));//µÈ´ýʱ¼äµ½´ï
SysTick->CTRL&=~SysTick_CTRL_ENABLE_Msk; //¹Ø±Õ¼ÆÊýÆ÷
SysTick->VAL =0X00; //Çå¿Õ¼ÆÊýÆ÷
}
#endif
delay.h：
#ifndef __DELAY_H
#define __DELAY_H
#include "sys.h"
//
//STM32F103ºËÐÄ°åÀý³Ì
//¿âº¯Êý°æ±¾Àý³Ì
/********** mcudev.taobao.com ³öÆ· ********/
//ʹÓÃSysTickµÄÆÕͨ¼ÆÊýģʽ¶ÔÑÓ³Ù½øÐйÜÀí
//°üÀ¨delay_us,delay_ms
//
void delay_init(void);
void delay_ms(u16 nms);
void delay_us(u32 nus);
#endif
sys.c:
#include "sys.h"
//STM32F103ºËÐÄ°åÀý³Ì
//¿âº¯Êý°æ±¾Àý³Ì
/********** mcudev.taobao.com ³öÆ· ********/
//
//STM32¿ª·¢°å
//ϵͳÖжϷÖ×éÉèÖû¯
//********************************************************************************
void NVIC_Configuration(void)
{
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2); //ÉèÖÃNVICÖжϷÖ×é2:2λÇÀÕ¼ÓÅÏȼ¶£¬2λÏìÓ¦ÓÅÏȼ¶
}
sys.h:
#ifndef __SYS_H
#define __SYS_H
#include "stm32f10x.h"
//
//STM32F103ºËÐÄ°åÀý³Ì
//¿âº¯Êý°æ±¾Àý³Ì
/********** mcudev.taobao.com ³öÆ· ********/
//
//0,²»Ö§³Öucos
//1,Ö§³Öucos
#define SYSTEM_SUPPORT_UCOS 0 //¶¨ÒåϵͳÎļþ¼ÐÊÇ·ñÖ§³ÖUCOS
//λ´ø²Ù×÷,ʵÏÖ51ÀàËƵÄGPIO¿ØÖƹ¦ÄÜ
//¾ßÌåʵÏÖ˼Ïë,²Î¿¼<<CM3ȨÍþÖ¸ÄÏ>>µÚÎåÕÂ(87Ò³~92Ò³).
//IO¿Ú²Ù×÷ºê¶¨Òå
#define BITBAND(addr, bitnum) ((addr & 0xF0000000)+0x2000000+((addr &0xFFFFF)<<5)+(bitnum<<2))
#define MEM_ADDR(addr) *((volatile unsigned long *)(addr))
#define BIT_ADDR(addr, bitnum) MEM_ADDR(BITBAND(addr, bitnum))
//IO¿ÚµØÖ·Ó³Éä
#define GPIOA_ODR_Addr (GPIOA_BASE+12) //0x4001080C
#define GPIOB_ODR_Addr (GPIOB_BASE+12) //0x40010C0C
#define GPIOC_ODR_Addr (GPIOC_BASE+12) //0x4001100C
#define GPIOD_ODR_Addr (GPIOD_BASE+12) //0x4001140C
#define GPIOE_ODR_Addr (GPIOE_BASE+12) //0x4001180C
#define GPIOF_ODR_Addr (GPIOF_BASE+12) //0x40011A0C
#define GPIOG_ODR_Addr (GPIOG_BASE+12) //0x40011E0C
#define GPIOA_IDR_Addr (GPIOA_BASE+8) //0x40010808
#define GPIOB_IDR_Addr (GPIOB_BASE+8) //0x40010C08
#define GPIOC_IDR_Addr (GPIOC_BASE+8) //0x40011008
#define GPIOD_IDR_Addr (GPIOD_BASE+8) //0x40011408
#define GPIOE_IDR_Addr (GPIOE_BASE+8) //0x40011808
#define GPIOF_IDR_Addr (GPIOF_BASE+8) //0x40011A08
#define GPIOG_IDR_Addr (GPIOG_BASE+8) //0x40011E08
//IO¿Ú²Ù×÷,Ö»¶Ôµ¥Ò»µÄIO¿Ú!
//È·±£nµÄֵСÓÚ16!
#define PAout(n) BIT_ADDR(GPIOA_ODR_Addr,n) //Êä³ö
#define PAin(n) BIT_ADDR(GPIOA_IDR_Addr,n) //ÊäÈë
#define PBout(n) BIT_ADDR(GPIOB_ODR_Addr,n) //Êä³ö
#define PBin(n) BIT_ADDR(GPIOB_IDR_Addr,n) //ÊäÈë
#define PCout(n) BIT_ADDR(GPIOC_ODR_Addr,n) //Êä³ö
#define PCin(n) BIT_ADDR(GPIOC_IDR_Addr,n) //ÊäÈë
#define PDout(n) BIT_ADDR(GPIOD_ODR_Addr,n) //Êä³ö
#define PDin(n) BIT_ADDR(GPIOD_IDR_Addr,n) //ÊäÈë
#define PEout(n) BIT_ADDR(GPIOE_ODR_Addr,n) //Êä³ö
#define PEin(n) BIT_ADDR(GPIOE_IDR_Addr,n) //ÊäÈë
#define PFout(n) BIT_ADDR(GPIOF_ODR_Addr,n) //Êä³ö
#define PFin(n) BIT_ADDR(GPIOF_IDR_Addr,n) //ÊäÈë
#define PGout(n) BIT_ADDR(GPIOG_ODR_Addr,n) //Êä³ö
#define PGin(n) BIT_ADDR(GPIOG_IDR_Addr,n) //ÊäÈë
void NVIC_Configuration(void);
#endif
Then add usart.c, bsp_i2c.c, delay.c, sys.c to the project file, as shown below:
4. Effect display
AHT20 temperature and humidity collection
V. Summary
Through this experiment, I learned more about the I2C bus communication protocol and the use of the AHT20 temperature and humidity sensor, and successfully completed the stm32 temperature and humidity (AHT20) acquisition experiment through I2C, which has benefited a lot!
6. References
https://blog.csdn.net/qq_43279579/article/details/111597278
https://blog.csdn.net/hhhhhh277523/article/details/111397514
https://blog.csdn.net/qq_46467126/article/details/121436790