iic接口读写._c

atmage8中的I2C口读写程序

//ICC-AVR application builder : 2009-3-12 17:05:04
// Target : M8
// Crystal: 8.0000Mhz

#include <iom8v.h>
#include <macros.h>

void port_init(void)
{
 PORTB = 0x00;
 DDRB  = 0x00;
 PORTC = 0x00; //m103 output only
 DDRC  = 0x00;
 PORTD = 0x00;
 DDRD  = 0x00;
}

//call this routine to initialize all peripherals
void init_devices(void)
{
 //stop errant interrupts until set up
 CLI(); //disable all interrupts
 port_init();

 MCUCR = 0x00;
 GICR  = 0x00;
 TIMSK = 0x00; //timer interrupt sources
 SEI(); //re-enable interrupts
 //all peripherals are now initialized
}

/*************************************************************************
用    途:iic发送接收
Taget   :mega8
crystal :8M
介    绍:PC4-SDA
         PC5-SCK/SCL
//***********************************************************************
 I2C 状态定义
 MT 主方式传输 MR 主方式接受
***************************/
#define START			0x08
#define RE_START		0x10
#define MT_SLA_ACK		0x18
#define MT_SLA_NOACK 	0x20
#define MT_DATA_ACK		0x28
#define MT_DATA_NOACK	0x30

#define MR_SLA_ACK		0x40
#define MR_SLA_NOACK	0x48
#define MR_DATA_ACK		0x50
#define MR_DATA_NOACK	0x58

#define RD_DEVICE_ADDR 0xA1  //前4位器件固定,后三位看连线,最后1位是读写指令位
#define WD_DEVICE_ADDR 0xA0
#define Start()		 (TWCR=(1<<TWINT)|(1<<TWSTA)|(1<<TWEN))		//启动I2C
#define Stop()		 (TWCR=(1<<TWINT)|(1<<TWSTO)|(1<<TWEN))		//停止I2C
#define Wait()		 {while(!(TWCR&(1<<TWINT)));}				//等待中断发生
#define TestAck()	 (TWSR&0xf8)								//观察返回状态
#define SetAck		 (TWCR|=(1<<TWEA))							//做出ACK应答
#define SetNoAck	 (TWCR&=~(1<<TWEA))							//做出Not Ack应答
#define Twi()		 (TWCR=(1<<TWINT)|(1<<TWEN))				//启动I2C
#define Write8Bit(x) {TWDR=(x);TWCR=(1<<TWINT)|(1<<TWEN);}		//写数据到TWDR
/*延时子程序*/
void delay_ms(int time)
{
 int i;
 for(;time>0;time--)
  for(i=0;i<1000;i++);
}
//初始化
void iic_init()
{
 TWBR= 0x20; //设置波特率
 TWSR= 0x00; //设置预分频比
 TWCR= 0x44; //使能应答，使能TWI
 DDRC|=(1<<PC4)|(1<<PC5);
 PORTC|=(1<<PC4)|(1<<PC5);
}
/*********************************************
I2C总线写一个字节
返回0:写成功
返回1:写失败
**********************************************/
unsigned char iic_write(unsigned char Wdata,unsigned char RegAddress)
{
   Start();						//I2C启动
   Wait();
   if(TestAck()!=START) 
	  return 1;					//ACK
	  
   Write8Bit(WD_DEVICE_ADDR);	//写I2C从器件地址和写方式
   Wait();
   if(TestAck()!=MT_SLA_ACK) 
	  return 1;		            //ACK
	  			
   Write8Bit(RegAddress);		//写器件相应寄存器地址
   Wait();
   if(TestAck()!=MT_DATA_ACK) 
	 return 1;				    //ACK
	 
   Write8Bit(Wdata);			 	//写数据到器件相应寄存器
   Wait();
   if(TestAck()!=MT_DATA_ACK) 
	  return 1;				    //ACK	
	  
   Stop();  						//I2C停止
   delay_ms(100);				//延时
   return 0;
}  

/*********************************************
I2C总线读一个字节
返回非0:读成功
返回0:读失败
**********************************************/
unsigned char iic_read(unsigned RegAddress)
{
   unsigned char temp;
   Start();//I2C启动
   Wait();
   if (TestAck()!=START) 
	   return 0;			 		//ACK	   
	   
   Write8Bit(WD_DEVICE_ADDR);	//写I2C从器件地址和写方式
   Wait(); 
   if (TestAck()!=MT_SLA_ACK) 
	   return 0;				    //ACK
	   
   Write8Bit(RegAddress);		//写器件相应寄存器地址
   Wait();
   if (TestAck()!=MT_DATA_ACK) 
	   return 0;
	   
   Start();	   				   	//I2C重新启动
   Wait();
   if (TestAck()!=RE_START)  
	   return 0;
	   
   Write8Bit(RD_DEVICE_ADDR);	//写I2C从器件地址和读方式
   Wait();
   if(TestAck()!=MR_SLA_ACK)  
	   return 0;				   //ACK
	   
   Twi();	 				   //启动主I2C读方式
   Wait();
   if(TestAck()!=MR_DATA_NOACK) 
	   return 0;					//ACK	
	   
   temp=TWDR;        //读取I2C接收数据
   Stop();          //I2C停止
   return temp;
}
//****************************************************************************
void main()
{
 unsigned char i,j;
 port_init();
 init_devices();
 
 iic_init();
 
 i=iic_write(0xaa,0X10);//在0X10地址写入数据0XAA
 if (i==0)
 	PORTB=0x1;//若写入失败(i=0),D口全灭；若读出成功，D口输出0XAA
 else
 	PORTB=0x2;
 j=iic_read(0X10);//读出0x10地址的数据
 if(j==1)
	PORTD=0xff;	//若读出失败(j=1),D口全灭；若读出成功，D口输出0XAA
 else
	PORTD=j;
 while(1)
 {
  ;
 }
}