PA: EQU 80H ;PORT A
PB: EQU 81H ;port B
PC: EQU 82H ;port C
CR: EQU 83H ;control register
ORG 0000H
JMP START
ORG 0024H
RET
START:
LXI SP,2010H
MVI A,90H
OUT CR ;configure the ppi
MVI A,00H
OUT PB
MVI A,00H
XRI 01H
MAIN:
CALL PSB_SCN
JMP MAIN
PSB_SCN: ;function for scanning psb
MVI C,00H ;counter for psb scan index
IN PA ;first scanning instant
ORI 00H ;check if button is pressed or not
JZ START ;jump to start if no switch pressed
MOV D,A
CALL DLY20MS ;call delay
IN PA
CMP D ;check valid press
JNZ RT_PSB
X: ;generate psb index
INR C
RAR
JNC X
CALL DISP
DISP: ;function for 7s diplay
LXI H,TABLE ;initialize M with lut address
MOV A,C
SUI 01H
ADD L ;add index to M value
MOV L,A
MOV A,M
OUT PB
RET
DLY20MS: ;DELAY function
