[Punctuality Atom] Learning and use of IIC (unfinished...)

前言

由于bThe station is from the Jiangxi University of Science and Technologystm32c8t6The video has not been updated yetIICvideo of communication,So here I learned from the official video of Punctual Atomic.

IIC简介

I2C协议

Agreement and Code

空闲状态-开始信号-The code for the stop signal is used

//产生IIC起始信号
void IIC_Start(void)
{
    
	SDA_OUT();     //sda线输出
	IIC_SDA=1;	   //SDA = 1,SCL = 1 空闲状态 
	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;//钳住I2C总线,准备发送或接收数据 
}	

//产生IIC停止信号
void IIC_Stop(void)
{
    
	SDA_OUT();//sda线输出
	IIC_SCL=0;SDA = 0,SCL = 0 to prepare for the stop signal
	IIC_SDA=0;//STOP:when CLK is high DATA change form low to high
 	delay_us(4);
	IIC_SCL=1; 
	IIC_SDA=1;//发送I2C总线结束信号
	delay_us(4);							   	
}

//等待应答信号到来
//返回值：1,接收应答失败
// 0,接收应答成功
u8 IIC_Wait_Ack(void)
{
    
	u8 ucErrTime=0;
	SDA_IN();      //SDA设置为输入 
	IIC_SDA=1;delay_us(1);	   
	IIC_SCL=1;delay_us(1);	 
	while(READ_SDA)//数据线是 高 就一直等,It is considered invalid until the low level is reached
	{
    
		ucErrTime++;
		if(ucErrTime>250)
		{
    
			IIC_Stop();
			return 1;
		}
	}
	IIC_SCL=0;//时钟输出0 低电平 
	return 0;  
} 

应答信号

//产生ACK应答
void IIC_Ack(void)
{
    
	IIC_SCL=0;
	SDA_OUT();
	IIC_SDA=0;     //SDA始终为 低 产生应答
	delay_us(2);
	IIC_SCL=1;
	delay_us(2);
	IIC_SCL=0;
}
//不产生ACK应答 
void IIC_NAck(void)
{
    
	IIC_SCL=0;
	SDA_OUT();
	IIC_SDA=1;       //SDA始终为 高 不产生应答
	delay_us(2);
	IIC_SCL=1;
	delay_us(2);
	IIC_SCL=0;
}	

Below is the function to send a byte and read a byte

//IIC发送一个字节
//返回从机有无应答
//1,有应答
//0,无应答 
void IIC_Send_Byte(u8 txd)
{
                            
    u8 t;   
	SDA_OUT(); 	    
    IIC_SCL=0;//拉低时钟开始数据传输
    for(t=0;t<8;t++)
    {
                  
        //IIC_SDA=(txd&0x80)>>7;
		if((txd&0x80)>>7)      //准备数据
			IIC_SDA=1;
		else
			IIC_SDA=0;
		txd<<=1; 	  
		delay_us(2);   //对TEA5767这三个延时都是必须的
		IIC_SCL=1;
		delay_us(2); 
		IIC_SCL=0;	
		delay_us(2);
    }	 
} 	    

如下图所示

SDA在SCLPrepare data for low time,SCL在0、1、0变化过程中,SDA时钟为高电平

//读1个字节,ack=1时,发送ACK,ack=0,发送nACK 
u8 IIC_Read_Byte(unsigned char ack)
{
    
	unsigned char i,receive=0;
	SDA_IN();//SDA设置为输入 在SCLRead the signal when it is high,Just the opposite of sending
    for(i=0;i<8;i++ )
	{
    
        IIC_SCL=0; 
        delay_us(2);
		IIC_SCL=1;
        receive<<=1;  //The entire data is shifted one bit to the left,If five digits are received,00012345,读取数据6,左移一位00123456
        if(READ_SDA)receive++;   //After shifting to the left, the lowest is changed to0 to the lowest bit++
		delay_us(1); 
    }					 
    if (!ack)
        IIC_NAck();//发送nACK 不应答信号
    else
        IIC_Ack(); //发送ACK 应答信号
    return receive;
}

EEPROM（24C02）