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we are interfacing 3x4 matrix keyboard and interfacing it with port 1 of P89C51RD2 microcontroller. We are connecting column to P1.0 to P1.3 and row to P1.4 to P1.6. could anybody have code in C
Thanks for replying i tried the key board, my logic is correct but when i m fusing the only last rows keys are working here i m sending my code actually here i m connetcing 12 switch 3x4 matrix to mc.Rows are to P1.6,P1.5,P1.4 and columns are to lower nibble of P1 and port0 to respective LED for checking .please find mistake and do correction in that.waiting for ur +ve response,thanks ////////////
#include <stdio.h> /*standared inclide file for main and other c functions */ #include <AT89X51.H> unsigned char var_keynumber; //for key indentification #pragma OPTIMIZE(6) //for reitteration #pragma SAVE void delay(void) //delay function for debaunse 20ms { TMOD=01; // ;timer 0 ,mode 1 TL0=0xE0; TH0=0xB1; TR0=1; again: if (TF0!=1) goto again; //if (TF0!=1) TR0=0; //;stoP timer TF0=0; // ;clear tf0 flag } #pragma RESTORE //start the Program////////////////////////////////////////////////////////// void main(void) { EA=0; // disable interrupt*/ P1 =0x0F; //set port 1 as input SP=0x07; //initialize stack pointer while(1) //loop forever { #pragma asm push ACC //save accumulator and flag push PSW #pragma endasm P0=0x00; //initially all output leds are off P2=0x00; //initially all output leds are off P1_4=0; //mask lower bit ground all the rows P1_5=0; P1_6=0; //checking previous key is released or not nadREL: if((P1_3==1)&&(P1_2==1)&&(P1_1==1)&&(P1_0==1)) delay(); else goto nadREL; //checking for new key is pressed or not nadNEW: if((P1_3==1)&&(P1_2==1)&&(P1_1==1)&&(P1_0==1)) goto nadNEW; else delay(); //scan for pressed key P1_4=0; //row 0 P1_5=1; P1_6=1; P1_0=0; if((P1_3==1)&&(P1_2==1)&&(P1_1==1)&&(P1_0==0)) var_keynumber=0;goto LAST; else if((P1_3==1)&&(P1_2==1)&&(P1_1==0)&&(P1_0==1)) var_keynumber=1;goto LAST; else if((P1_3==1)&&(P1_2==0)&&(P1_1==1)&&(P1_0==1)) var_keynumber=2;goto LAST; else if((P1_3==0)&&(P1_2==1)&&(P1_1==1)&&(P1_0==1)) var_keynumber=3;goto LAST; P1_4=1; //row 1 P1_5=0; P1_6=1; if((P1_3==1)&&(P1_2==1)&&(P1_1==1)&&(P1_0==0)) var_keynumber=4;goto LAST; else if((P1_3==1)&&(P1_2==1)&&(P1_1==0)&&(P1_0==1)) var_keynumber=5;goto LAST; else if((P1_3==1)&&(P1_2==0)&&(P1_1==1)&&(P1_0==1)) var_keynumber=6;goto LAST; else if((P1_3==0)&&(P1_2==1)&&(P1_1==1)&&(P1_0==1)) var_keynumber=7;goto LAST; P1_4=1; //row 2 P1_5=1; P1_6=0; if((P1_3==1)&&(P1_2==1)&&(P1_1==1)&&(P1_0==0)) var_keynumber=8;goto LAST; else if((P1_3==1)&&(P1_2==1)&&(P1_1==0)&&(P1_0==1)) var_keynumber=9;goto LAST; else if((P1_3==1)&&(P1_2==0)&&(P1_1==1)&&(P1_0==1)) var_keynumber=10;goto LAST; else if((P1_3==0)&&(P1_2==1)&&(P1_1==1)&&(P1_0==1)) var_keynumber=11;goto LAST; goto nadNEW //if error then check again LAST: switch(var_keynumber) { case 0:P0_0=1; break; case 1:P0_1=1; break; case 2:P0_2=1; break; case 3:P0_3=1; break; case 4:P0_4=1; break; case 5:P0_5=1; break; case 6:P0_6=1; break; case 7:P0_7=1; break; case 8:P2_6=1; break; case 9:P2_7=1; break; case 10:P2_5=1;break; case 11:P2_4=1;break; #pragma asm Pop ACC //save accumulator and flag from stack Pop PSW #pragma endasm } //switch end } //while end } //main end ///////////////////////////////////////////////////////////////////////////