twi_nbyte.c

avr单片机的twi(i2c）的程序

/*
8m
*/
#include <iom16v.h>
#include <macros.h>
unsigned char a[16],b[16];
void a_init(void)
{	 
	 unsigned char i;
	 for(i=0;i<16;i++)
	     a[i]=i+1;
} 
void delay_1ms(void)
{    unsigned int i;
	 for(i=1142;i>0;i--)
	 ;
}
/*****nms延时程序*****/
void delay_nms(unsigned int n)
{	 
	 unsigned int i;
	 for(i=n;i>0;i--)
	 	delay_1ms();
}
void port_init(void)
{	 
	 DDRA=0X00;
	 PORTA=0XFF;
	 DDRB=0Xff;
	 PORTB=0XFF;
	 DDRD=0XFF;
	 PORTD=0XFF;
	 DDRC=0XFF;
	 PORTC=0XFF;
}
void usart_init(void)
{	 
	 UCSRB=0X00;
	 UCSRA=0X20;
	 UCSRC=0X86;
	 
	 UBRR=0X33;//FOSC=8M
	 UCSRB=0X98;
}
void usart_txc(unsigned char td)
{	 
	 CLI();
	 while(!(UCSRA&(1<<UDRE)))
	 ;
	 UDR=td;
}
void twi_init(void)
{	 
	 TWCR=0X00;
	 TWBR=0X0F;
	 TWSR=0X03;
	 TWCR=(TWEN<<1);
}
void start(void)
{	 
	 TWCR=(1<<TWINT)|(1<<TWSTA)|(1<<TWEN);
	 while(!(TWCR&(1<<TWINT)))
	 ;
}
void send_data(unsigned char data)
{	 
	 TWDR=data;
	 TWCR=(1<<TWINT)|(1<<TWEN);
	 while(!(TWCR&(1<<TWINT)))
	 ;
}
	 
void stop(void)
{	 
	 TWCR=(1<<TWINT)|(1<<TWSTO)|(1<<TWEN);
}
unsigned char at24c02_write(unsigned char add,unsigned char * d,unsigned char n)
{	 
	 unsigned char i;
	 for(i=0;i<n;i++)
	 {    start();//发送开始
	      if((TWSR&0XF8)!=0x08)
	 	  		return 1;
	 	  send_data(0xa0);//发送地址
	 	  if((TWSR&0XF8)!=0x18)
	 	  		return 1;
	 	  send_data(add++);
	 	  if((TWSR&0XF8)!=0x28)
	 	  		return 1;
	 	  send_data(*(d));
	 	  if((TWSR&0XF8)!=0x28)
	 	  		return 1;
		  stop();
		  delay_nms(3);
		  usart_txc(*(d));
		  d++;  
	 }
	 return 0;
}
unsigned char at24c02_read(unsigned char add,unsigned char *add1,unsigned char n)
{	 
	 unsigned char i;
	 for(i=0;i<n;i++)
	 {    
	 	  start();
	 	  if((TWSR&0XF8)!=0x08)
	 	  		return 1;
	 	  send_data(0xa0);
	 	  if((TWSR&0XF8)!=0x18)
	 	  		return 1;
	 	  send_data(add);
	 	  if((TWSR&0XF8)!=0x28)
	 	  		return 1;
	 	  start();
	 	  if((TWSR&0XF8)!=0x10)
	 	  		return 1;
	 	  send_data(0xa1);
	 	  if((TWSR&0XF8)!=0x40)
	 	  		return 1;
	 	  TWCR=(1<<TWINT)|(1<<TWEN);
	 	  while(!(TWCR&(1<<TWINT)));
	 	  if((TWSR&0xf8)!=0x58) 
	 	  		return 1;
	 	  add1[i]=TWDR;
		  delay_nms(1);
		  usart_txc(add1[i]);
		  stop();
		  add++;
		  delay_nms(1);
	 }
	 return 0;
}
void main(void)
{	 
	 unsigned char add=0,i;
	 port_init();
	 twi_init();
	 usart_init();
	 a_init();
	 at24c02_write(add,a,16);
	 add=0x00;
	 at24c02_read(add,b,16);
}