Line 6 pedal board: Programming the expression pedals

The expression pedal board contains two analog circuits for the two pedals, a simple switch and a LED. The connector has one pin for each, plus a ground and Vcc pin.

The pedals use an infrared LED and photo-transistor that is slightly amplified by a transistor. They produce a weak analog value. I have not been able to get reliable readings on the pins. I suspect that the unit has to be embedded into its casing to prevent stray light from reaching the receptor.UPDATE: By measuring voltage at a different point on the pedal circuits, I was able to get full readings, from 0 to approximately 5 volts. I Guess that transistor is not used as an amplifier but as a switching transistor. I will replace the connections on the socket. I will just bypass the transistors.

The LED on the left (led9) will be addressed directly with a digital pin from the Arduino. The switch is activated by pressing firmly on the pedal, to engage the WAH function on the effects board. It will be read directly with a digital or analog pin.

/*
  
 */
int led9=9;
int express=1;
int wah=2;

void setup() {
  Serial.begin(9600);
  pinMode(led9, OUTPUT);

}

void loop() {
//Read analog signals from both pedals
  int pedValue1 = analogRead(express);
  int pedValue2 = analogRead(wah);
  Serial.print(pedValue1);
  Serial.print(" ");
  Serial.println(pedValue2);
//read sw9 from the pedal sub-board
  int switch9 = analogRead(A3);
  if (switch9 != 0)
    digitalWrite(led9,LOW);
    else
    digitalWrite(led9,HIGH);

}