?? led.asm
字號:
BIT_COUNT DATA 07FH
TIMER DATA 07EH
TIMER1 DATA 07DH
TEMP DATA 07CH
DATA_IN DATA 021H
DATA_OUT DATA 020H
CLK BIT P3.5
DAT BIT P3.4
KEY BIT P3.3
ORG 000H
JMP START
ORG 100H
START: MOV SP,#2FH ;設置堆棧
MOV TIMER,#50H
DELAY: MOV TIMER1,#0FFH ;延時已確保7281完成復位
DELAY1: DJNZ TIMER1,DELAY1
DJNZ TIMER,DELAY
MOV DATA_OUT,#12H
CALL SEND ;8271初始化
MOV DATA_OUT,#80H
CALL SEND ;設置為164模式,不反相
MAIN: JB KEY,MAIN ;等待按鍵
MOV DATA_OUT,#93H ;讀鍵值
CALL SEND
CALL RECEIVE ;讀出數據
MOV DATA_OUT,#15H ;HEX譯碼指令
CALL SEND
MOV TEMP, DATA_IN
ANL TEMP,#0F0H ;鍵值高4位在第一位顯示
MOV A,TEMP
SWAP A
ORL A,#10H
MOV DATA_OUT,A
CALL SEND
MOV DATA_OUT,#15H ;HEX譯碼指令
CALL SEND
MOV A,DATA_IN
ANL A,#0FH ;取鍵值低4位
MOV DATA_OUT,A ;在0位顯示
CALL SEND
JMP MAIN
SEND: CLR CLK
SETB CLK
WAIT1: JB DAT,SEND
CLR CLK
SETB CLK
WAIT2: JNB DAT,WAIT2
MOV BIT_COUNT,#08H
SENDLOOP:MOV C,DATA_OUT.7
MOV DAT,C
CLR CLK
SETB CLK
MOV A,DATA_OUT
RL A
MOV DATA_OUT,A
NOP
NOP
NOP
DJNZ BIT_COUNT,SENDLOOP
SETB DAT
NOP
NOP
NOP
NOP
RET
RECEIVE: CLR CLK
SETB CLK
WAIT3: JB DAT,WAIT3
CLR CLK
SETB CLK
MOV BIT_COUNT,#08H
REC_LOOP:NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
MOV A,DATA_IN
MOV C,DAT
RLC A
MOV DATA_IN,A
CLR CLK
SETB CLK
DJNZ BIT_COUNT,REC_LOOP
NOP
NOP
NOP
NOP
RET
END
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