I don’t have a sketch for this project, just doing some thinking before I pullout the keyboard (this is my phone). I was interested in writing a program that uses a predetermined time limit, for instance having a definition like...

#define RUNTIME 30000 

So the game runs for 30 seconds. By doing this it would be a simple matter of changing the 30000 to 60000 and uploading to the Arduino.

After thinking about that a while, I would prefer to be able to adjust the time using a selector switch.
So my question is.... if I use a 1p4t (on-on-on-on) rotary selector switch, assign each position to a pin and run 5v to the common. Each pin would defined as RUNTIME and a different time limit, 30000, 60000, 90000, 120000, three pins would be LOW and one HIGH depending on position. Then using IF and ELSE statements in the loop setup would I be able to switch the times? I know once the Arduino is powered up the selector switch would need to be at the correct location and if you choose to change the “RUNTIME” a reset would need to be pressed.

Thank you for any assistance or ideas.

  • 1
    Better to use GND not +5V and use the INPUT_PULLUP mode for the pins. If you don't you then need to add a pulldown resistor to all 4 inputs.
    – Majenko
    Mar 13, 2018 at 13:35
  • You would not HAVE to reset when changing the switch position. you could periodically check the switch input and update the value while running.
    – Chad G
    Mar 13, 2018 at 16:36
  • you could use an analog pin and 4 voltages instead of many pins.
    – dandavis
    Mar 13, 2018 at 20:01
  • for a simpler keyswitch circuit look at the keypad schematic at the bottom of this page ... in the "More" section .... dfrobot.com/wiki/index.php/… ......... use the code on the page for reference
    – jsotola
    Mar 14, 2018 at 1:30

1 Answer 1


If I understand you well, it's very easy.

Assuming the 4 outputs of the switch will be connected to 4 GPIO's you just can check for the state of each GPIO and act on it

// Pin numbers where switch 1 to 4 are attached to.
#define PIN_SWITCH_1  8
#define PIN_SWITCH_2  9
#define PIN_SWITCH_3 10
#define PIN_SWITCH_4 11

unsigned long timer_value = 1000; // No switch selected

void setup()
     // Set switch pins to input mode.
     pinMode(PIN_SWITCH_1, INPUT); 
     pinMode(PIN_SWITCH_2, INPUT); 
     pinMode(PIN_SWITCH_3, INPUT); 
     pinMode(PIN_SWITCH_4, INPUT); 

     // Check switches
     if (digitalRead(PIN_SWITCH_1) == HIGH)
         timer_value = 30000;
     else if (digitalRead(PIN_SWITCH_2) == HIGH)
         timer_value = 60000;
     else if (digitalRead(PIN_SWITCH_3) == HIGH)
         timer_value = 90000;
     else if (digitalRead(PIN_SWITCH_4) == HIGH)
         timer_value = 120000;
         // Keep default value

 void loop()
     // Here you can use timer_value to check for the end of the game.
  • 1
    Thank you everyone for your input. I will be moving ahead with this project.
    – Bender
    Mar 13, 2018 at 16:58
  • 2
    pin 1 is a trap for the beginner?
    – Juraj
    Mar 13, 2018 at 18:13
  • 1
    @Juraj ... yes it's mean of me to use those pins ... I was not near an Arduino so I should check which are really free and obvious to use. Mar 13, 2018 at 23:12

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