push button

const int led = 2;
const int sw = 3;
int val;
void setup()
{
  pinMode(sw, INPUT);
  pinMode(led, OUTPUT);
}
void loop()
{
  val = digitalRead(sw);
  if (val == HIGH)//我的板子4*4是提昇電阻
  //我要沒按是０Ｖ，有按是５ｖ
    digitalWrite(led, LOW);
  else
    digitalWrite(led, HIGH);
}

方法2:

const int led = 2;
const int sw = 3;
int val;
void setup()
{
  pinMode(sw, INPUT);
  pinMode(led, OUTPUT);
}
void loop()
{
  val = digitalRead(sw);
  if (val == LOW)//我的板子4*4是提昇電阻
  //我要沒按是０Ｖ，有按是５ｖ
    digitalWrite(led, HIGH);
  else
    digitalWrite(led, LOW);
}

方法3:
const int led = 2;
const int sw = 3;
int val;
void setup()
{
  pinMode(sw, INPUT);
  pinMode(led, OUTPUT);
}
void loop()
{
  val = digitalRead(sw);
  if (val != LOW)//我的板子4*4是提昇電阻，不等於
    //我要沒按是０Ｖ，有按是５ｖ
    digitalWrite(led, LOW);
  else
    digitalWrite(led, HIGH);
}