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#include <reg52.h> ?h8/\~Dw
sbit LED1 = P0^0; 4-\4G"4
sbit LED2 = P0^1; XV!UeBq
sbit LED3 = P0^2; '=IuwCB|;
sbit LED4 = P0^3; 2Mu(GUe;
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sbit KEY1 = P2^0; DE?@8k
sbit KEY2 = P2^1; $'lJ_jL
sbit KEY3 = P2^2; &jDRRT3
sbit KEY4 = P2^3; ,->
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void delay(); gKb5W094@
void main() =PoPp
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bit keybuf = 1; //按键值暂存,临时保存按键的扫描值 bre6SP@
bit backup = 1; //按键值备份,保存前一次的扫描值 *8 ]
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while (1) FRTvo
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keybuf = KEY4; //把当前扫描值暂存 F,XJGD*
if (keybuf != backup) //当前值与前次值不相等说明此时按键有动作 g:"Hg-s
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delay(); //延时大约10ms }Z\+Qc<<
if (keybuf == KEY4) //判断扫描值有没有发生改变,即按键抖动 p|w;StLy
{ dk2o>jI4;
if (backup == 0) //如果前次值为0,则说明当前是弹起动作 B Zw#ACU
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P0 =~P0; //计数值显示到数码管上 ;D<rGkry
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backup = keybuf; //更新备份为当前值,以备进行下次比较 z~a]dMs"(P
} ?r~](l
} 9$'Edi=6
} g:c
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//软件延时函数,延时约10ms m;I;{+"u
void delay() 'w7{8^Z2
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unsigned int i = 1000; >:P3j<xTv
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while (i--); w@2LFDp
} ihhnB