i2c.c

ATmega128芯片的测试程序

#include "i2c.h"


byte i2c_local_buff[5];

 void init_i2c(void)
 {
  int i;
  
  	bool FirstCheck = TRUE;
	while(!((PIND&0x01)&&(PIND&02)))
	{
		if(!FirstCheck)
		{
		    
			DDRD |= 0x20;//将PD5置为输出，RST_MOST;
	        PORTD &= ~_BV(PD5);//复位OS81050
	        for(i=0;i<10000;i++);
	       PORTD |= _BV(PD5);//启动OS81050	
	        DDRD &= 0xdf;
			
		}
		else
		{
			for(i=0;i<10000;i++);
		}
		FirstCheck = FALSE;
	}
   
	
   /////关于i2c的TWI的 设置。。。。。  
  	TWCR =0x00;
	TWBR = 0x0A;
	TWSR = 0x00;
	TWCR = 	(1<<TWEN)|                                          // Enable TWI-interface and define TWI pins.
         	(0<<TWIE)|(0<<TWINT)|                               // Disable Interupt.
         	(0<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|                    // No Signal requests.
         	(0<<TWWC); 
   /////下面这两条是什么语句，去掉？？      
	DDRD &= 0xfc; 
	PORTD |= 0x03;
}

byte i2c_read_buff(byte DevAddr, byte *Buf, byte Length)
{
	byte rAddr = DevAddr|0x01;
	Length --;
	Start();	   
	Wait();
	if (TestAck()!=START) return 0;	   
	Write8Bit(rAddr);
	Wait(); 
	if(TestAck()!=MR_SLA_ACK)  return 0;
	while( Length --)
	{
		TwiAck();
		Wait();
		if(TestAck()!=MR_DATA_ACK) return 0;	
		*(Buf ++) = TWDR;
	}
	Twi();
	Wait();
	if(TestAck()!=MR_DATA_NOACK) return 0;	
	*Buf = TWDR;
	Stop();
	return 1;
}
byte i2c_write_buff(byte DevAddr, byte *Buf, byte Length)
{
   
    int i;
	Start();
	Wait();
	if(TestAck()!=START) return 1;
	Write8Bit(DevAddr);
	Wait();
	if(TestAck()!=MT_SLA_ACK) return 1;
	
	while(Length -- )//写字节；
	{
		Write8Bit(*(Buf++));
	  	Wait();
	  	if(TestAck()!=MT_DATA_ACK) return 1;
	 }
	 Stop();
	 

	 
	 for(i=0;i<10000;i++);//加延迟，以使芯片将缓冲区数据保存到需要的存储器位置；
	 return 0;
}
byte i2c_read_byte(byte DevAddr)
{
	byte result;
	i2c_read_buff(DevAddr, i2c_local_buff, 1);
	result = i2c_local_buff[0];
	return (result);
}
byte i2c_write_byte(byte DevAddr,byte data)
{
	byte result;
	i2c_local_buff[0] = data;
	result = i2c_write_buff(DevAddr, i2c_local_buff, 1);
	return (result);
}
word i2c_read_word(byte DevAddr)
{
	word  result;

	i2c_read_buff(DevAddr, i2c_local_buff, 2);
	result = ((word ) i2c_local_buff[0]) << 8;
	result |= (word ) i2c_local_buff[1];
	return (result);
	
}
word 	pm_read (byte *buf)
{

	byte addr;
    byte data;
	word  length;
	word  pm_length;
	
	addr = INIC_ADDR | 0x01;					        // sending slave address + READ
	
	Start();	   
	Wait();
	if (TestAck()!=START) return 0;	   
	Write8Bit(addr);
	Wait(); 
	if(TestAck()!=MR_SLA_ACK)  return 0;
	
	TwiAck();
	Wait();
	if(TestAck()!=MR_DATA_ACK) return 0;	
	data = TWDR;
	*(buf++) = data;
	length = (word ) data <<8;	
	
	TwiAck();
	Wait();
	if(TestAck()!=MR_DATA_ACK) return 0;
	data = TWDR;
	*(buf++) = data;									        // read data from register, put in buffer
	length |= data;									        // or in the low byte of length
	pm_length = length + 2;							        // add 2 for 2 bytes of pm length itself, save for return
 
 if((0<length)&&(length<64))
 {	while (length--)
	{
		if (length != 0)								    // then this is not last byte
		{
			TwiAck();
			Wait();
			if(TestAck()!=MR_DATA_ACK) return 0;
			data = TWDR;
			*(buf++) = data;								    // read data from register, put in buffer
		}
		else											    // last byte, don't ack
		{
			Twi();
			Wait();
			if(TestAck()!=MR_DATA_NOACK) return 0;	
			data = TWDR;
			*(buf++) = data;								    // read data from register, put in buffer
		}
	}
	
 }
	Stop();
	

	
	if (length == 0xFFFF)                                   // everything went OK? (this compiler ends loop above with length at -1)
	{
		return(pm_length);                                  // returns # of bytes in Port Message
	}
	else
	{
		return 0;					        // got a NACK during transmission & broke out of loop
	}	
}