今天上午寫了atmega16的I2C硬件接口程序，程序不難，只是給初學的朋友一個思路，不過通過和51的軟件模擬I2C程序比較發(fā)現(xiàn)，AVR的I2C硬件接口使程序更簡單了，

程序功能：先由atmega16向EEPROM中某地址寫數(shù)字71，然后再從EEPROM里讀出來顯示到數(shù)碼管上；

#include

#include <avrdef.h>

unsigned charconstduacode[]={0x3f,0x06,0x5b,0x4f,

0x66,0x6d,0x7d,0x07,

0x7f,0x6f,0x77,0x7c,

0x39,0x5e,0x79,0x71}; //0-f 數(shù)字模*/

void delay(unsigned int);

void display(unsigned int);

void send1byte(unsigned char address,unsigned char data);

unsigned char read1byte(unsigned char address);

#define START TWCR=BIT(7)|BIT(5)|BIT(2)

#define STOP TWCR=BIT(7)|BIT(4)|BIT(2)

#define WRITE(x) {TWDR=x; TWCR=BIT(7)|BIT(2);}

void main()

{unsigned char i=0;

DDRC=0xff;

while(1)

{

send1byte(4,71);

i=read1byte(4);

display(i);

}

}

void send1byte(unsigned char address,unsigned char data)

{

START;

while(!(TWCR&0x80));

WRITE(0xa0);

while(!(TWCR&0x80));

WRITE(address);

while(!(TWCR&0x80));

WRITE(data);

while(!(TWCR&0x80));

STOP;

delay(2);

}

unsigned char read1byte(unsigned char address)

{

unsigned char temp;

START;

while(!(TWCR&0x80));

WRITE(0xa0);

while(!(TWCR&0x80));

WRITE(address);

while(!(TWCR&0x80));

START;

while(!(TWCR&0x80));

WRITE(0xa1);

while(!(TWCR&0x80));

TWCR=BIT(7)|BIT(2);

while(!(TWCR&0x80));

temp=TWDR;

STOP;

return temp;

}

void display(unsigned int dat)

{

unsigned char a[4],i;

for(i=0;i<4;i++)

{

a[3-i]=dat%10;

dat/=10;

}

DDRB=0xff; DDRD=0xff;

for(i=0;i<4;i++)

{

PORTB=duacode[a[i]];

PORTD&=~BIT(i);

delay(10);

PORTD|=BIT(i);

}

}

void delay(unsigned int x)

{

unsigned int a; unsigned char b;

for(a=x;a>0;a--)

for(b=100;b>0;b--);

}