单片机期末考试的五道程序题
1、晶振为12Mhz，编写延迟时间为1ms的延迟子程序
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| DELAY: MOV R5,#10H
LOOP1: MOV R6,#250H
LOOP2: DJMZ R6,LOOP2
DJMZ R5,LOOP1
RETI
END
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2.查询地址30H-60H中，出现AAH的次数
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| ORG 0000H
AJMP MAIN
ORG 0100H
MAIN:MOV R1,#60H
MOV R0,#0
START:DEC R1
CJNE R1,#02FH,NEXT
AJMP EXT
NEXT:CJNE @R1,#0AAH,START
INC R0
AJMP START
EXT:END
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3.设计令定时器T0在P2.0上产生频率为20Hz方波
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| ORG 0000H
AJMP MAIN
ORG 000BH
AJMP CTMO
ORG 0030H
MAIN:MOV TMOD,#01H
MOV TH0,#9EH
MOV TL0,#58H
SETB EA
SETB ET0
SETB TR0
WAIT:SJMP WAIT
CTMO:MOV TH0,#9EH
MOV TL0,58H
CPL P2.0
EXIT
END
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4.串行口通信
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| ORG OOOOH
AJMP MAIN
ORG 0100H
MAIN:MOV SP,#60H
MOV R0,#0
MOV SCON,#40H
START: LCALL DELAY
INC R0
MOV A,R0
MOV SBUF,A
JNB T1,$
CLR T1
LJMP SATRT
END
DELAY:MOV R5,#10
LOOP1:MOV R6,#200
LOOP2:MOV R7,#250
DJMZ R7,$
DJMZ R6,LOOP2
DJMZ R5,LOOP1
RET
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5.按键显示
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| ORG 0000H
AJMP MAIN
ORG 0100H
MAIN:MOV P1,#0
NET1:JB P0.0,NET2
MOV P1,#09FH
MET2:JB P0.1,NET3
MOV P1,#0A4H
NET3:JB P0.2,NET4
MOV P1,#0B0H
NET4:JB P0.3,NET0
MOV P1,#99H
LMP NET1
END
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