slave._c

ICCavr编写的TWI总线协议读写函数

/*
	文件名：slave.c 
	两个Mega8间的TWI通信实验从模式单片机程序
	
	外部4MHz晶振
	
	芯艺 2004-09-02 --- 2004-09-03
*/

#include <iom8v.h>
#include <stdio.h>
#include"delay.h"
#include"twi.h"
#define uint unsigned int
#define uchar unsigned char
#define  uchar  unsigned char

#define TWI_ADDRESS 0X32

/*
#define  TW_STATUS  (TWSR&0xf8)
#define  TW_WRITE    0xa0
#define  TW_READ    0xa1
*/
//初始化
void IoInit(void)
{
	//使能SCL、SDA引脚内部上拉电阻
	DDRC=0;
	PORTC=0X30;

	//TWI接口初始化,从器件模式
	TWAR=TWI_ADDRESS | (1<<TWGCE);
	TWCR=(1<<TWEA) | (1<<TWEN);
}

void main(void)
{
	uchar i,j=0;
	
	IoInit();
	uart_init();
	printf("START\n");
	while(1)
	{
		//while ((TWCR & (1<<TWINT)) == 0);  //完成一次接收
		i=TW_STATUS;                       //看看状态
		 Delay_nms(100);
		switch(i)
		{
			case TW_SR_SLA_ACK:
				printf("START\nSLA+W\n");
				break;
			case TW_SR_DATA_ACK:
				if(j==0)
					printf("收到:%d",TWDR);
				else
					printf(" %d",TWDR);
				j++;
				break;
			case TW_SR_STOP:
				printf(";\nSTOP\n\n");
				j=0;
				break;
			default:
				printf("error:%x",(int)i);
				break;
		}
		TWCR=(1<<TWEA) | (1<<TWEN)|(1<<TWINT);	//清除TWINT位
	}

}