int led_state = LOW;
int button_state;
int last_button_state;
void setup()
{
pinMode(4, OUTPUT);
pinMode(14, INPUT_PULLUP);
button_state = digitalRead(14);
}
void loop()
{
last_button_state = button_state;
button_state = digitalRead(14);
delay(10);
if (last_button_state == HIGH && button_state == LOW) {
led_state = !led_state;
digitalWrite(4, led_state);
}
}