MAX485两个单片机半双工通信

#include<reg52.h> #define uint unsigned int #define uchar unsigned char sbit P0_0=P0^0; uchar idata table[17]={0xfe,0xfd,0xfb,0xf7,0xef,0xdf,0xbf,0x7f,0xaa,0xbd,0xee,0xdd,0x99,0xfd,0xff,0xff}; uchar idata table2[10]; uchar num,temp; uchar num1=0,flag; void delay(uint z) { uint x,y; for(x=z;x>0;x--) for(y=110;y>0;y--); } uchar keyscan(); void int0(void) interrupt 0 { int m; P1=0xff; for(m=0;m<5;m++) { P1=table2[m]; delay(500); } } void main() { uchar n=0; uchar m; uchar i=0; flag=1; TMOD=0x20;//设置定时器1为工作方式2 TH1=0xe8; TL1=0xe8; TR1=1; EA=1; //总中断开启 EX0=1; //外部中断INT0开启 IT0=1; REN=1; SM0=0; SM1=1; while(flag) i=keyscan(); flag=1; while(1) { if(num1==0) { RI=0; P0_0=0; while(!RI); delay(500); P1=SBUF; m=SBUF; table2[n]=m; n++; RI=0; } else if(num1==1) { while(flag) i=keyscan(); flag=1; P0_0=1; SBUF=table[i-1]; while (!TI); P1=table[i-1]; TI=0; } } } uchar keyscan() { P2=0xfe; temp=P2; temp=temp&0xf0; while(temp!=0xf0) { delay(5); temp=P2; temp=temp&0xf0; while(temp!=0xf0) { temp=P2; switch(temp) { case 0xee:{num=1;flag=0;} break; case 0xde:{num=2; flag=0;} break; case 0xbe:{num=3; flag=0;} break; case 0x7e:{num=4; flag=0;} break; } while(temp!=0xf0) { temp=P2; temp=temp&0xf0; } } } P2=0xfd; temp=P2; temp=temp&0xf0; while(temp!=0xf0) { delay(5); temp=P2; temp=temp&0xf0; while(temp!=0xf0) { temp=P2; switch(temp) { case 0xed:{num=5;flag=0;} break; case 0xdd:{num=6;flag=0;} break; case 0xbd:{num=7;flag=0;} break; case 0x7d:{num=8;flag=0;} break; } while(temp!=0xf0) { temp=P2; temp=temp&0xf0; } } } P2=0xfb; temp=P2; temp=temp&0xf0; while(temp!=0xf0) { delay(5); temp=P2; temp=temp&0xf0; while(temp!=0xf0) { temp=P2; switch(temp) { case 0xeb:{num=9; flag=0;} break; case 0xdb:{num=10; flag=0;} break; case 0xbb:{num=11;flag=0;} break; case 0x7b:{num=12; flag=0;} break; } while(temp!=0xf0) { temp=P2; temp=temp&0xf0; } } } P2=0xf7; temp=P2; temp=temp&0xf0; while(temp!=0xf0) { delay(5); temp=P2; temp=temp&0xf0; while(temp!=0xf0) { temp=P2; switch(temp) { case 0xe7:{num=13; flag=0;} break; case 0xd7:{num=14;num1=2; flag=0;} break; case 0xb7:{num=15;num1=1;flag=0;} break; case 0x77:{num=16; flag=0;num1=0;} break; } while(temp!=0xf0) { temp=P2; temp=temp&0xf0; } } } return num; return flag; }