C51多地址I2C程序.doc

连接多个相同地址I2C设备的C51程序本人初学C,曾为这个问题大伤脑筋_,就是一个单片机系统有两个以上的相同地址的I2C设备,无法用两个同一对SDA/SCL引脚,#include stc89c51.h#include iic.hsbit scl0=P35;sbit sda0 = P34;sbit scl1= P33;sbit sda1 = P32;/这里只写了两个I2C设备,如果需要可以再加上 sbit scl2=xx; sbit sda2=xx; 实际上多个设备的scl脚可以共用unsigned char iic_delay_time = 8;void scl(device,value);void sda(device,value);bit sdasense(char device);/ delayvoid iic_delay(unsigned char m) unsigned char n; for(n=0;nm;n+);/void scl(device,value) if (device=0) /设备1 scl1=value; if (device=1) /设备2 scl2=value;void sda(device,value) if (device=0) /设备1 sda1=value; if (device=1) /设备2 sda2=value;bit sdasense(char device)switch(device) case 1: return sda1; break; case 2: return sda2; break; /启动I2C总线的函数，当scl为高电平时使sda产生一个负跳变 void iic_start(device) sda(device,1); scl(device,1); iic_delay(iic_delay_time); sda(device,0); iic_delay(iic_delay_time); scl(device,0); iic_delay(iic_delay_time/2);/终止I2C总线，当scl为高电平时使sda产生一个正跳变void iic_stop(device) scl(device,0); sda(device,0); scl(device,1); iic_delay(iic_delay_time); sda(device,1); iic_delay(iic_delay_time);/发送应答信号void iic_ack(device) sda(device,0); scl(device,1); scl(device,0); sda(device,1);/发送无应答信号void iic_noack(device) sda(device,1); scl(device,1); scl(device,0); /检测应答信号bit iic_testack(device) bit errorbit; /真确应答,返回0 sda(device,1); iic_delay(iic_delay_time); scl(device,1); iic_delay(iic_delay_time); errorbit=sdasense(device); scl(device,0); iic_delay(iic_delay_time); return(errorbit);/发送一个字节void iic_write8bit(device,unsigned char input) unsigned char temp; for(temp=0;temp8;temp+) if(inputtemp)&0x80) sda(device,1); else sda(device,0); scl(device,1); iic_delay(iic_delay_time); scl(device,0); /读一个字节unsigned char iic_read8bit(device) unsigned char temp,rbyte=0; for(temp=0;temp8;temp+) scl(device,1); iic_delay(iic_delay_