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Re: 關於port的預設值
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版主
 
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PORTC 設為輸入其輸入值會變來變去，是否忘了接 Pull-Up 電阻了，找 4 個 47Kohm 的電阻接 Vcc 吧。
發表於: 2005/3/9 16:37
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關於port的預設值
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新會員
 
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我是使用icd2除錯器及picdem2 plus公版.....
我在練習簡單的鍵盤掃描.....因為有問題所以我先try一行四獵的掃描..........我已portb輸出......portc輸入,下面是這一小段的部分程式.......我有疑問的是我利用watch及sfr視窗來監看port .....就目前來說...reset時我監看portc.....她的腳位預設都會一值改變,有時候是oxfc或是0xdc或是0xd8......2; 當我執行程式用step one時....portc的值也會變來變去的(ps:鍵盤完全沒按) 所以在我的if條件判斷時.....有時條件就會自動成立.... 請問是什麼原因呢...... TRISB=0X00; // set PORTB as outputs TRISD=0X00; //SET PORTD AS INPUTS TRISC=0XFF; PORTB=0X0F; PORTD=0X00; while(1){ PORTB=0x0E; if(RC2==0){PORTD=0x00;keyup();} if(RC3==0){PORTD=0x01;keyup();} if(RC4==0){PORTD=0x02;keyup();} if(RC6==0){PORTD=0x03;keyup();}
發表於: 2005/3/9 11:39
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