實踐中，單片機端口在連接開關器件時都要考慮消抖的問題，或在硬件上增加延遲，或是增加軟件延遲查詢的功能模塊。這里，我們考慮這樣一個檢測電路：單片機連接一個開關和兩個LED。程序是這樣的，如果開關的消抖正確，就點亮LED1，否則就閃亮LED2。按下開關，點亮LED1，釋放開關，LED1即熄滅。我們加入20毫秒的消抖延遲時間。當檢測到開關為低電平時，單片機在延遲20毫秒后再次檢測開關的狀態(tài)。如果此時開關狀態(tài)為高，則LED2就閃亮，如為低則點亮LED1。 源代碼： led1 bit P2.0
led2 bit P2.1
switch1 bit P1.0
ORG 0000h
setb switch1 //initialize switch 1 as input
setb led1 //Turn OFF LED1
setb led2 //Turn OFF LED2 wait:
jb switch1,wait // Wait till switch1 has been pressed
call debounce_delay
jb switch1,c1_wait
//switch low even after debouncing period
//switch has been succesfully debounced
clr led1 //Turn ON LED1
jnb switch1,$ //wait till switch has been released
setb led1 //Turn OFF LED1
ajmp wait c1_wait:
//Switch PIN high after debounce period so error in debouncing
cpl led2
ajmp wait debounce_delay: //Subroutine for generating 20ms delay
MOV r7,#245
l1_debounce_delay:
MOV r6,#40
djnz r6,$
djnz r7,l1_debounce_delay
ret END
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66821730(技術支持)
