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#include <reg52.h> COmu.'%*
sbit LED1 = P0^0; $1Zr.ERL|(
sbit LED2 = P0^1; IreY8.FND
sbit LED3 = P0^2; @]p{%" $
sbit LED4 = P0^3; YHMJ5IM@.
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sbit KEY1 = P2^0; MU\Pggs
sbit KEY2 = P2^1; 1kR. .p<"
sbit KEY3 = P2^2; _x^rHADp
sbit KEY4 = P2^3; I5`>XfO)
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void delay(); oJ`=ob4WDo
void main() ^7Z;=]8J
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bit keybuf = 1; //按键值暂存,临时保存按键的扫描值 :R>RCR2g)
bit backup = 1; //按键值备份,保存前一次的扫描值 TQ0ZBhd
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while (1) b#R$P]dr=
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keybuf = KEY4; //把当前扫描值暂存 AjoIL
if (keybuf != backup) //当前值与前次值不相等说明此时按键有动作 lNl.lI\t)y
{ .yFO]
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delay(); //延时大约10ms \fuz`fK:
if (keybuf == KEY4) //判断扫描值有没有发生改变,即按键抖动 lnm@DWhf
{ lP*=4Jh
if (backup == 0) //如果前次值为0,则说明当前是弹起动作 `l/nAKg?W
{ t%0c$c
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P0 =~P0; //计数值显示到数码管上 ?~E"!
} K_-m:P
backup = keybuf; //更新备份为当前值,以备进行下次比较 hw*u. 46
} }pnp._j
} {2q0Ko<
} lNtxM"G&
} 5h0Hk<N
//软件延时函数,延时约10ms /e*fsQ>M:
void delay() c h((u(G
{ j+{cc: h"X
unsigned int i = 1000; -Fu,oEj{*
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while (i--); %e3E}m>
} AE~@F4MK