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1、 多机通信系统单片机a,b,c. a为主机，bc为从机。a上有一个外部中断0输入，按第一次a的两个LED亮500ms，再按一下，b机的两个LED灯亮500ms，第三次按下c机的两个LED灯亮500ms，然后周而复始。两个数码管分别显示0/1/2, 和abc（bc由从机反馈）/*主从通信基本步骤：1 主机从机初始化为方式2或者3，从机都置SM2=1，允许中断2 主机置TB8=1，发送从机地址3 所有从机均接收主机发送要寻址的从机地址4 被寻址的从机确认地址后，置本机SM2=0，向主机返回地址，供主机核对5 核对无误后，主机向被寻址的从机发送命令，通知从机接受或者发送数据。6 本次通信结束后，主从
2、机重置SM2=1，主机可再对其他从机寻址*/*主机a：*#include #define uchar unsigned char#define uint unsigned intuchar leddata=0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F,0x77,0x7C,0x39,0x5E,0x79,0x71,0x40,0x00;uchar Mode;sbit P10 = P10;sbit P13 = P13;sbit P17 = P17;sbit P20 = P20;sbit P21 = P21;void UART_init() TMOD
3、 = 0x20; TH1 = 0xfd; TL1 = 0xfd; TR1 = 1; SCON = 0xd0; ES = 1; EX0 = 1; IT0 = 1; /INT0下跳触发 EA = 1; TI = 0;void DelayMs(int ms) uchar i; while(ms-) for(i=0; i120; i+);void putc_to_SerialPort(uchar c) SBUF = c; while(TI = 0); TI = 0;void MasterControl(unsigned char Addr, unsigned char Comd) TB8 = 1; p
4、utc_to_SerialPort(Addr); DelayMs(50); TB8 = 0; putc_to_SerialPort(Comd); DelayMs(50);Ex0_int(void) interrupt 0 P0 = leddataMode; P20 = 0; if(Mode = 0) P2 = leddata10; P10 = 0; P13 = 0; DelayMs(500); P10 = 1; P13 = 1;/ MasterControl(b,C);/ MasterControl(c,C); else if(Mode = 1) P10 = 1; P13 = 1; Maste
5、rControl(b,O); / MasterControl(c,C); else if(Mode = 2) P10 = 1; P13 = 1; / MasterControl(b,C); MasterControl(c,O); Mode = (Mode + 1) % 3; com_int(void) interrupt 4 if(RI) RI = 0; if(SBUF = b) P2 = leddata11; if(SBUF = c) P2 = leddata12; void main(void) P0 = 0x00; P1 = 0xff; P2 = 0x00; UART_init(); M
6、ode = 0; while(1);*从机b：*#include #define uchar unsigned charuchar RecData;sbit P10 = P10;sbit P13 = P13;void UART_init() TMOD = 0x21; TH1 = 0xfd; TL1 = 0xfd; TR1 = 1; SCON = 0xf0; ES = 1; PS = 1; EA = 1;void DelayMs(int ms) uchar i; while(ms-) for(i=0; i120; i+);void putc_to_SerialPort(uchar c) SBUF
7、 = c; while(TI = 0); TI = 0;com_int(void) interrupt 4 if(RI) RecData = SBUF; RI = 0; if(RB8 = 1) /地址 if(RecData = b) /是自己的地址,置SM2=0,准备接受数据 SM2 = 0; putc_to_SerialPort(b); else /不是自己的地址 SM2 = 1; if(RB8 = 0) /数据 if(RecData=O) P10 = 0; P13 = 0; DelayMs(500); P10 = 1; P13 = 1; if(RecData=C) P10 = 1; P13
8、 = 1; SM2 = 1; void main(void) P0 = 0xff; P1 = 0xff; UART_init(); while(1);*从机c：*#include #define uchar unsigned charuchar RecData;sbit P10 = P10;sbit P13 = P13;void UART_init() TMOD = 0x21; TH1 = 0xfd; TL1 = 0xfd; TR1 = 1; SCON = 0xf0; ES = 1; PS = 1; EA = 1;void DelayMs(int ms) uchar i; while(ms-)
9、 for(i=0; i120; i+);void putc_to_SerialPort(uchar c) SBUF = c; while(TI = 0); TI = 0;com_int(void) interrupt 4 if(RI) RecData = SBUF; RI = 0; if(RB8 = 1) /地址 if(RecData = c) /是自己的地址,置SM2=0,准备接受数据 SM2 = 0; putc_to_SerialPort(c); else /不是自己的地址 SM2 = 1; if(RB8 = 0) /数据 if(RecData=O) P10 = 0; P13 = 0; DelayMs(500); P10 = 1; P13 = 1; SM2 = 1; if(RecData=C) P10 = 1; P13 = 1; SM2 = 1; void main(void) P0 = 0xff; P1 = 0xff; UART_init(); while(1); 多机通信系统实验清单： 排阻 （1K） 10片 80C51芯片 10片 按键开关（2脚） 5个 发光二极管 30个 电容 10uF 15个 30pF 30个 数码管 10个 石英晶体（1.212MHZ） 15个 电阻 8.2K欧 15个 220欧 45个 51芯片插座 10个
