Ms80c51 Keyboard Scan

// Ms80c51 <br/> // 4*4 Keyboard Scan <br/> // P2 ^ 1 ~ P2 ^ 3 connect to the keyboard row <br/> // P2 ^ 4 ~ P2 ^ 7 keyboard column <br/> // led_scan.h is the custom header file required for LED display <br/> # include "led_scan.h" <br/> # include <reg51.h> <br/> # define unchar unsigned char <br/> // returns the number of digits of special data 1 <br/> // If 00001000, 4 is returned, if 00000100 returns 3 <br/> unchar getlocation (unchar value) <br/>{< br/> unchar location = 0; <br/> If (value! = 0) <br/>{< br/> while (value) <br/>{< br/> location ++; <br/> value = value> 1; <br/>}< br/> return location; <br/>}< br/> void delay () <br/>{< br/> unsigned char a, B; <br/> for (a = 0; A <50; A ++) <br/> for (B = 0; B <100; B ++); <br/>}< br/> void main () <br/>{< br/> unchar ROW = 0; <br/> unchar column = 0; </P> <p> P2 = 0x0f; // 00001111 <br/> while (1) <br/>{< br/> If (P2! = 0x0f) <br/>{< br/> ROW = getlocation (~ (P2 | 0xf0); // locate the row of the pressed key <br/> P2 = 0xf0; // 11110000 <br/> If (P2! = 0xf0) <br/>{< br/> column = getlocation (~ (P2> 4) | 0xf0 )); // locate the column of the key to be pressed <br/>}< br/> else <br/>{< br/> ROW = 0; <br/> column = 0; <br/>}< br/> delay (); <br/> ledstore (row, column ); // load <br/> ledscan (); // LED display <br/> ROW = 0; <br/> column = 0; <br/> P2 = 0x0f; <br/>}< br/>}