Timer (Emergencie)

[Bruno Cunha]

Hi, i have this project where i control the the time (0-20 s) that a relay is actuated, i have a button to turn the relay and i want another button to turn off the relay in any moment, like a emergencie button. I though about running a parallel program but i dont know if it possible, here is the code.

"
int potPin = A0;
int ledPin = 13;
const int buttonPin = 2;

void setup() {
Serial.begin(9600);
pinMode(ledPin, OUTPUT);

pinMode(buttonPin, INPUT);

}

void loop()
{
int buttonState = digitalRead(buttonPin);

int val = analogRead(potPin);
long tempo = (val*19.550342131);
Serial.print(val);
Serial.print("tempo:");

// read the value from the sensor
if (buttonState==HIGH) {

digitalWrite(ledPin, HIGH);
delay(tempo);
digitalWrite(ledPin, LOW);
} else {}; // turn the ledPin off

delay(500);
}
"

[gohan]

Use an if statement instead of delay and use millis to count time passed, when time is up turn off pin.

[Tmaster]

if it is an emergency button should be connected directly to relay (connected by hardware). And not using code,because if arduino it's freezed it will not respond and you cant stop it