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#define LED 13
#define KEY 2
void setup()
{
// put your setup code here, to run once:
pinMode(LED,OUTPUT);
pinMode(KEY,INPUT_PULLUP);
}
void loop()
{
if(digitalRead(KEY) == LOW)
{
delay(20);
if(digitalRead(KEY) == LOW)
{
digitalWrite(LED, !digitalRead(LED));
while(digitalRead(KEY) == LOW);
}
}
}
程式如上
使用PIN2內建上拉電阻
比較有疑問的是這句
digitalWrite(LED, !digitalRead(LED));
LED的輸出電位一直和按鈕讀入電位相反
開關在按下時不是都是LOW,也就是說 每進LOOP一次LED就是輸出HIGH
這樣為何燈泡會有明暗變化?照理說不是輸出high燈泡亮,LOW燈泡按嗎?
可是感覺在LOOP中,只會輸出HIGH阿...因為按鈕按下讀入是LOW,LED就輸出HIGH
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