?? gg202.asm
字號:
;gg202.asm/forsum2
;for 讀A口送B口<芯片8255A:A口接8開關(guān),B口接LED,pc7接1S脈沖>
;for 產(chǎn)生1S脈沖<芯片8253-5>
;2005-05
;lcy/p_Sa
data SEGMENT
PA EQU 280h
PB EQU 281h
PC EQU 282h
PCTL EQU 283h
T0 EQU 288H
T1 EQU 289H
T2 EQU 28aH
TCTL EQU 28bH
data ENDS
stack0 SEGMENT para stack
DW 20h DUP(0)
stack0 ENDS
coseg SEGMENT
ASSUME CS:coseg,DS:data,SS:stack0
start: MOV AX, data
MOV DS, AX
;================MOV-DS-AX==============
MOV DX, TCTL
MOV AL, 27h ;00-10-011-1B:0通道,高8位,方式3(方波發(fā)生器),BCD記數(shù)
OUT DX, AL
MOV DX, T0
MOV AL, 10h ;1us=>1ms方波
OUT DX, AL
MOV DX, TCTL
MOV AL, 65h ;01-10-010-1B:1通道,高8位,方式2(頻率發(fā)生器),BCD記數(shù)
OUT DX, AL
MOV DX, T1
MOV AL, 10h ;1ms=>1s脈沖
OUT DX, AL
MOV AL, 98h ;1-0011-000B:A口方式0輸入,B口方式0輸出
MOV DX, PCTL
OUT DX, AL
MOV CX, 10h
L1:MOV DX, PC
IN AL, DX
TEST AL, 80h
JZ L1 ;判斷pc7上升沿
MOV DX, PA
IN AL, DX
MOV DX, PB
OUT DX, AL
MOV DX, PC
L2:IN AL, DX
TEST AL, 80h
JNZ L2 ;判斷pc7下降沿
LOOP L1
;================INT-21H================
MOV AH, 4ch
INT 21h
coseg ENDS
END start
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