STM32---IIC

IIC Software simulation

Hardware IIC You need to read the chip manual to use the specified multiplexing port . adopt stm32 control GPIO Mouth simulation IIC sequential , Just any two routes GPIO To control IIC.

Code foreword

Realization IIC Reading and writing EEPROM stay EEPROM 0X18 Write a byte of data to the address of 78.
Use EEPROM model AT24C02 common 256 byte , Be careful not to exceed the address range when using .
For details, please refer to IIC Timing and AT24C02 manual

Analog timing

GPIO initialization

The following is a IIC.h Macro definitions and declarations in header files SCL Line selection PB6;SDA Line selection PB7

//iic.h Documents in 
#ifndef __IIC_H
#define __IIC_H

#include "stm32f10x.h"

#define IIC_POST GPIOB
#define IIC_SCL GPIO_Pin_6
#define IIC_SDA GPIO_Pin_7

//IO Direction setting 
#define SDA_IN() {
      GPIOB->CRL&=0X0FFFFFFF;GPIOB->CRL|=(u32)8<<28;}
#define SDA_OUT() {
      GPIOB->CRL&=0X0FFFFFFF;GPIOB->CRL|=(u32)3<<28;}

#define IIC_SDA_1 GPIO_SetBits(IIC_POST,IIC_SDA)
#define IIC_SDA_0 GPIO_ResetBits(IIC_POST,IIC_SDA)

#define IIC_SCL_1 GPIO_SetBits(IIC_POST,IIC_SCL)
#define IIC_SCL_0 GPIO_ResetBits(IIC_POST,IIC_SCL)

#define IIC_SDA_READ GPIO_ReadInputDataBit(IIC_POST,IIC_SDA)

void IIC_GPIO_Cfg(void);
void IIC_STOP(void);
void IIC_START(void);
void IIC_NACK(void);
void IIC_ACK(void);
u8 IIC_Read_Byte(void);
void IIC_WriteByte(uint8_t data);
u8 IIC_Wait_Ack(void);

#endif /* __IIC_H */

//iic.c Documents in 
void IIC_GPIO_Cfg()
{
    
	GPIO_InitTypeDef GPIO_InitStruct;
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB,ENABLE);

	GPIO_InitStruct.GPIO_Mode=GPIO_Mode_Out_OD;
	GPIO_InitStruct.GPIO_Pin=IIC_SCL|IIC_SDA;
	GPIO_InitStruct.GPIO_Speed=GPIO_Speed_50MHz;
	GPIO_Init(IIC_POST, &GPIO_InitStruct);
	GPIO_SetBits(IIC_POST,IIC_SCL|IIC_SDA); 	//PB6,PB7  High output 
	
}	

Start signal and stop signal

//iic.c Documents in 
/* *brief:  Software IIC Analog transmission start signal  */
void IIC_START()
{
    
	SDA_OUT()	//SDA Line out 
	IIC_SDA_1;	//SDA Output high level 
	IIC_SCL_1;	//SCL Output high level 
	delay_us(5);
	IIC_SDA_0;	//SDA Output low level 
	delay_us(5);
	IIC_SCL_0;	//SCL Output low level 
	delay_us(5);
}

/* *brief:  Software IIC Analog send stop signal  */
void IIC_STOP()
{
    
	SDA_OUT();	//sda Line out 
	IIC_SCL_0;	//SCL Output low level 
	IIC_SDA_0;	//SDA Output low level 
 	delay_us(4);
	IIC_SCL_1; 	//SCL Output high level 
	IIC_SDA_1;	//SDA Output high level 
	delay_us(4);	
}

The reply 、 Non reply and waiting for reply

//iic.c Documents in 

void IIC_NACK()
{
    
	SDA_OUT();
	IIC_SCL_0;
	IIC_SDA_1;
	delay_us(2);
	IIC_SCL_1;
	delay_us(2);
	IIC_SCL_0;
}

void IIC_ACK()
{
    
	SDA_OUT();
	IIC_SCL_0;
	IIC_SDA_0;
	delay_us(2);
	IIC_SCL_1;
	delay_us(2);
	IIC_SCL_0;
}

// Waiting for the answer signal to arrive 
// Return value ：1, Failed to receive response 
// 0, Received response successfully 
u8 IIC_Wait_Ack(void)
{
    
	u8 ucErrTime=0;
	SDA_IN();      //SDA Set to input  
	IIC_SDA_1;
	delay_us(2);	   
	IIC_SCL_1;
	delay_us(2);	 
	while(IIC_SDA_READ)
	{
    
		ucErrTime++;
		if(ucErrTime>250)
		{
    
			IIC_STOP();
			return 1;
		}
	}
	IIC_SCL_0;// Clock output 0 
	return 0;  
} 

Reading and writing 1 Bit byte function

//iic.c Documents in 
u8 IIC_Read_Byte(void)
{
    
	SDA_IN();
	u8 i;
	u8 value=0;
	for(i=0;i<8;i++){
    
		value <<=1;
		IIC_SCL_1;
		delay_us(5);
		if(IIC_SDA_READ){
    
			value++;
		}
		IIC_SCL_0;
		delay_us(5);
	}
	return value;
}

void IIC_WriteByte(u8 data)
{
                            
	SDA_OUT();
	u8 i;
	for(i=0;i<8;i++)
	{
    
		if(data &0x80){
    
			IIC_SDA_1;
		}
		else{
    
			IIC_SDA_0;
		}
		delay_us(5);
		IIC_SCL_1;
		delay_us(5);
		IIC_SCL_0;
		if(i==7)
		{
    
			IIC_SDA_1;
		}
		data <<=1;
		delay_us(5);
	}
} 

AT24C02

AT24C02 Address

The address is 1010+A2+A1+A0+ Read write bit
10100000 by AT20C02 Write the address
10100001 Read the address as

AT20C02 Write timing

AT24C02 Reading sequence

Write the following code according to the read-write address and read-write sequence ：

//AT24C02 The header file 
#ifndef __24C02_H
#define __24C02_H
#include "stm32f10x.h"

#define EEPROM_ADDR 0xA0

u8 AT24CXX_ReadOneByte(u8 addr);
void AT24C02_WriteByte(u8 addr,u8 data);
#endif /* __24C02_H */

//AT24C02 The source file 
#include "24c02.h"
#include "IIC.h"
#include "delay.h"


// stay AT24CXX Read a data at a given address 
//addr: The address to start reading  
// Return value  : Data read 
u8 AT24CXX_ReadOneByte(u8 addr)
{
    				  
	u8 temp=0;		  	    																 
    IIC_START();  
	IIC_WriteByte(0XA0);   // Send device address 0XA0, Writing data  

	IIC_Wait_Ack(); 
    IIC_WriteByte(addr);   // Sending address 
	IIC_Wait_Ack();	    
	IIC_START();  	 	   
	IIC_WriteByte(0XA1);           // Enter receive mode  
	IIC_Wait_Ack();	 
    temp=IIC_Read_Byte();		   
    IIC_STOP();// Create a stop condition  
	return temp;
}

// stay AT24CXX Write a data to the specified address 
//addr : The destination address of the write data  
//data: The data to be written  
void AT24C02_WriteByte(u8 addr,u8 data)
{
    
	// Send the start signal 
	IIC_START();
	
	// send out 24C02 Device address 
	IIC_WriteByte(0xA0);
	
	// Wait for the slave device to answer 
	IIC_Wait_Ack(); 
	
	// Send to write 24C02 An address of 
	IIC_WriteByte(addr);
	
	// Wait for the slave device to answer 
	IIC_Wait_Ack(); 
	   
	// Send byte  
	IIC_WriteByte(data);	
	
	// Wait for the slave device to answer 
	IIC_Wait_Ack(); 
	
	IIC_STOP();// Create a stop condition  
	delay_ms(10);	 
	
}

Main function code

#include "stm32f10x.h"
#include "usart.h"
#include "delay.h"
#include "IIC.h"
#include "24c02.h"
#include <stdio.h>
/************************************************ * 06 IIC *  author ： Mango Chen  *  date ：2022.2.9 *  Content ：iic Driver writing  *  Based on punctual atomic Elite Edition and reference documents  ************************************************/
u8 temp=0;
	
int main(void)
{
    
	
	Usart_Init();
	delay_init();
	IIC_GPIO_Cfg();
	AT24C02_WriteByte(18,78);
	delay_us(5);
	temp=AT24CXX_ReadOneByte(18);
		printf("temp:%d\n",temp);
	while(1){
    

		}
}

Program run results