I2C-bus.rar_I2C仲裁_总线控制

#include<reg52.h> #define uchar unsigned char #define uint unsigned int bit write=0; //写24C02的标志； sbit sda=P2^5; sbit scl=P2^4; sbit dula=P2^6; sbit wela=P2^7; uchar sec,tcnt; uchar code table[]={ 0x3f,0x06,0x5b,0x4f, 0x66,0x6d,0x7d,0x07, 0x7f,0x6f,0x77,0x7c, 0x39,0x5e,0x79,0x71}; void delay() { ;; } void delay1ms(uint z) { uint x,y; for(x=z;x>0;x--) for(y=110;y>0;y--); } void start() //开始信号 { sda=1; delay(); scl=1; delay(); sda=0; delay(); } void stop() //停止 { sda=0; delay(); scl=1; delay(); sda=1; delay(); } void respons() //应答 { uchar i; scl=1; delay(); while((sda==1)&&(i<250))i++; scl=0; delay(); } void init() { sda=1; delay(); scl=1; delay(); } void write_byte(uchar date) { uchar i,temp; temp=date; for(i=0;i<8;i++) { temp=temp<<1; scl=0; delay(); sda=CY; delay(); scl=1; delay(); } scl=0; delay(); sda=1; delay(); } uchar read_byte() { uchar i,k; scl=0; delay(); sda=1; delay(); for(i=0;i<8;i++) { scl=1; delay(); k=(k<<1)|sda; scl=0; delay(); } return k; } void write_add(uchar address,uchar date) { start(); write_byte(0xa0); respons(); write_byte(address); respons(); write_byte(date); respons(); stop(); } uchar read_add(uchar address) { uchar date; start(); write_byte(0xa0); respons(); write_byte(address); respons(); start(); write_byte(0xa1); respons(); date=read_byte(); stop(); return date; } void display(uchar bai_c,uchar sh_c) //显示程序 { dula=0; P0=table[bai_c]; //显示第一位 dula=1; dula=0; P0=0xff; wela=0; P0=0x7e; wela=1; wela=0; delay1ms(5); dula=0; P0=table[sh_c]; //显示第二位 dula=1; dula=0; P0=0xff; wela=0; P0=0x7d; wela=1; wela=0; delay1ms(5); } void main() { init(); sec=read_add(2); //读出保存的数据赋于sec if(sec>100) //防止首次读取出错误数据 sec=0; TMOD=0x01; //定时器工作在方式1 ET0=1; EA=1; TH0=(65536-50000)/256; //对TH0 TL0赋值 TL0=(65536-50000)%256; //使定时器0.05秒中断一次 TR0=1; //开始计时 while(1) { display(sec/10,sec%10); if(write==1) //判断计时器是否计时一秒 { write=0; //清零 write_add(2,sec); //在24c02的地址2中写入数据sec } } } void t0() interrupt 1 //定时中断服务函数 { TH0=(65536-50000)/256; //对TH0 TL0赋值 TL0=(65536-50000)%256; //重装计数初值 tcnt++; //每过50ms tcnt加一 if(tcnt==20) //计满20次（1秒）时 { tcnt=0; //重新再计 sec++; write=1; //1秒写一次24C02 if(sec==100) //定时100秒，再从零开始计时 sec=0; } }