Page 31 - The Journal of the Royal Society of Thailand

วารสารราชบััณฑิิตยสภา
ปีีท่� ๔๙ ฉบัับัท่� ๑ มกิราคุม-เมษาย์น ๒๕๖๗

ศาสตราจารย์์กิิตติคุุณ ดร.มงคุล เดชนคุรินทร์ 21

call delay1
mov al,0
out ppi_port2b,al ;turn off all LEDs
call delay1 ;wait 0.16 sec
call delay1
inc si ;next byte
loop dspl ;loop 99 times

mov al,byte ptr[si] ;last (100th) byte
out ppi_port2b,al ;show and retain data on Port 2B LEDs
call delay2 ;wait 0.6 sec
call delay2
call delay2
call delay2

jmp begn ;jump to start of principal loop

main endp
;******************************************

;Procedures
LedFlicker proc
;5-cycle flicker of LEDs on Port 2B
;input: data byte in al
push ax
push cx
mov ah,al ;save al in ah
mov cx,5
rpt: mov al,ah ;retrieve al
out ppi_port2b,al ;turn ON LEDs
call delay2 ;0.6-sec delay
mov al,0
out ppi_port2b,al ;turn OFF LEDs
call delay2 ;0.6-sec delay
loop rpt ;loop 5 times
pop cx
pop ax
ret
LedFlicker endp
;**********************************************

chknak proc
;check NAK=1 in ah.0 after calling i2c_wr
and ah,01h ;check bit ah.0 for "1"
cmp ah,00h
je extpr ;it's ACK="0", so return
mov al,11h ;code for NAK error
flick: call LedFlicker ;flicker Port 2B LEDs 5 cycles
jmp flick ;endless exit loop
extpr:
ret
chknak endp
;**********************************************