Microcontroller introductory experiment eight

;Experiment name: 2 independent keyboards control LED light experiment       ;
;Author:                Long Yi                 ;
;Version:               VER 1.0               ;
;Description:           Beginner's introductory experiment          ;
;Modification:                 None                   ;
;Programming language:           Assembly language              ;

;**********************************************;

         ORG  00H
START:   MOV  P0,#0FFH            ;Shield LED light
        MOV  P2,#0FFH            ;Shield independent keyboard
PANDUAN:  JNB  P2.7,LIANG          ;Judge whether the lit keyboard is pressed?
        JNB  P2.6,MIE           ;Judge whether the extinguished keyboard is pressed?
        JMP  PANDUAN             ;No keyboard is pressed, return to re-judge
LIANG:   CALL  DELAY             ;Software debounce
        JB   P2.7,PANDUAN        ;Is the lit key really pressed?
        JNB  P2.7,$             ;Is the lit key released?
        CLR  P0.0               ;Light up the LED light
        JMP  PANDUAN            ;Return to re-judge the keyboard
MIE:     CALL  DELAY             ;Software debounce
        JB   P2.6,PANDUAN        ;Is the extinguished key really pressed?
        JNB  P2.6,$             ;Is the extinguished key released?
        SETB  P0.0              ; Turn off the LED light
        JMP  PANDUAN            ; Return to re-judge the keyboard
DELAY:   MOV  R6,#20             ; Use 12MHZ crystal oscillator, the delay time is 0.01 seconds    
D1:      MOV  R7,#248
        DJNZ  R7,$
        DJNZ  R6,D1
        RET
         END