Using One Analog Pin to Read 4 Buttons - Arduino




The idea is to read the resistanse differense between them using resistors.
The buttons are connected in such way that each button add the resistors of the buttons before him to a serial out put.

I used 4 220ohm resistors and 4 buttons.

int sensorPin = A0;    
int sensorValue = 0;
void setup() {
  pinMode (sensorPin, INPUT_PULLUP);
  Serial.begin (9600);
void loop() {
  sensorValue = analogRead(sensorPin);    
  sensorValue =  (map (sensorValue, 18,44, 1, 5));
  if (sensorValue < 5 ) Serial.println (sensorValue); 

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    3 Discussions


    3 years ago

    Can someone please explain how this line works?
    sensorValue = (map (sensorValue, 18,44, 1, 5));


    5 years ago

    why couldn't you make a voltage divider before each button. Since this is a 10-bit adc, your 1024 steps could be chopped up into analog ranges for each button press.


    5 years ago

    Well this takes me back.. Old VCRs used too use this method... Old top load VCRs with 30' " wired" remotes. If a switch gets worn out and develops enough resistance it will mimic the next highest resistance switch next too it.