i2c.h

GY-27资料源码 ADXL345 HMC5883L

#include <macros.h>
#include "delay.h"

//使用AVR内部硬件iic，引脚定义
//PC0->SCL  ;  PC1->SDA
//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  0xA7	   //定义器件在IIC总线中的从地址,根据ALT ADDRESS地址引脚不同修改
#define WD_DEVICE_ADDR  0xA6	   //ALT  ADDRESS引脚接地时地址为0xA6，接电源时地址为0x3A

//常用TWI操作(主模式写和读)
#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

unsigned char I2C_Write(unsigned char RegAddress,unsigned char Wdata);
unsigned char I2C_Read(unsigned RegAddress);

/*********************************************
I2C总线写一个字节
返回0:写成功
返回1:写失败
**********************************************/
unsigned char I2C_Write(unsigned char RegAddress,unsigned char Wdata)
{
	  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_nms(10);				//延时  
	  return 0;
}

/*********************************************
I2C总线读一个字节
返回0:读成功
返回1:读失败
**********************************************/

unsigned char I2C_Read(unsigned RegAddress)

 {
	   unsigned char temp;
	   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;
	   
	   Start();	   				   	//I2C重新启动
	   Wait();
	   if (TestAck()!=RE_START)  
	   	  return 1;
	   
	   Write8Bit(RD_DEVICE_ADDR);	//写I2C从器件地址和读方式
	   Wait();
	   if(TestAck()!=MR_SLA_ACK)  
	   	  return 1;				   //ACK
	   
	   Twi();	 				   //启动主I2C读方式
	   Wait();
	   if(TestAck()!=MR_DATA_NOACK) 
	   	 return 1;					//ACK	
	   
	   temp=TWDR;//读取I2C接收数据
       Stop();//I2C停止
	   return temp;
      }