shmups.system11.org

  /*
   * Constants for analog pins
   */
  /*
   * analog read returns a value between 0-1023 with 0 = ground
   * and 1023 = analog reference (5v for this purpose)
   * For scart fast switch pin, < 0.4V is low, so 0.5V will be the target
   * (0.5V/(5V/1024)) should give the int value corresponding to 0.5V
   */
  const int activeInputVoltage = 102;
  const int I0 = A0;
  const int I1 = A1;
  const int I2 = A2;
  const int I3 = A3;
  const int I4 = A4;
  const int I5 = A5;
  const int I6 = A6;
  const int I7 = A7;

  /*
   * constants for digital pins
   */
  const int inAddr0 = 10;  //Input address bit 0 (EXT 5)
  const int inAddr1 = 5;   //Input address bit 1 (EXT 6)
  const int inAddr2 =  2;  //Input address bit 2 (EXT 7)

  //pin 12 is OVERRIDE (EXT 2) set low to enable
  const int overridePin = 12;

  /*
   * variables for code execution
   */
  //store the lowest numbered input detected this loop iteration
  int lowestEnabledInput;

  /*
   * store the input that is currently selected
   * store this so the digital pins don't need
   * to be reset every second
   */
  int currentSelectedInput = 8;//default to 8 so it will be overwritten first loop iteration

void setup() {
  //set up digital pins
 
  pinMode(overridePin, OUTPUT);
  digitalWrite(overridePin, LOW);   //enable OVERRIDE

  pinMode(inAddr0, OUTPUT);
  pinMode(inAddr1, OUTPUT);
  pinMode(inAddr2, OUTPUT);

  pinMode(I7, INPUT);
  pinMode(I6, INPUT);
  pinMode(I5, INPUT);
  pinMode(I4, INPUT);
  pinMode(I3, INPUT);
  pinMode(I2, INPUT);
  pinMode(I1, INPUT);
  pinMode(I0, INPUT);

  analogReference(EXTERNAL);

  Serial.begin(9600);
}

void loop() {
  // read inputs from highest to lowest fo find the highest
  // priority that is currently active

  Serial.print("beginning loop iteration, current input = ");
  Serial.print(currentSelectedInput);
  Serial.println();

  lowestEnabledInput = 8; //guarantee an input will be found to have a higher priority

  if(analogRead(I7) > activeInputVoltage) {
    Serial.println("Input 7 active");
    Serial.print("Voltage = ");
    Serial.print(analogRead(I7));
    Serial.println();
    lowestEnabledInput = 7;
  }
  if(analogRead(I6) > activeInputVoltage) {
    Serial.println("Input 6 active");
    Serial.print("Voltage = ");
    Serial.print(analogRead(I6));
    Serial.println();
    lowestEnabledInput = 6;
  }
  if(analogRead(I5) > activeInputVoltage) {
    Serial.println("Input 5 active");
    Serial.print("Voltage = ");
    Serial.print(analogRead(I5));
    Serial.println();
    lowestEnabledInput = 5;
  }
  if(analogRead(I4) > activeInputVoltage) {
    Serial.println("Input 4 active");
    Serial.print("Voltage = ");
    Serial.print(analogRead(I4));
    Serial.println();
    lowestEnabledInput = 4;
  }
  if(analogRead(I3) > activeInputVoltage) {
    Serial.println("Input 3 active");
    Serial.print("Voltage = ");
    Serial.print(analogRead(I3));
    Serial.println();
    lowestEnabledInput = 3;
  }
  if(analogRead(I2) > activeInputVoltage) {
    Serial.println("Input 2 active");
    Serial.print("Voltage = ");
    Serial.print(analogRead(I2));
    Serial.println();
    lowestEnabledInput = 2;
  }
  if(analogRead(I1) > activeInputVoltage) {
    Serial.println("Input 1 active");
    Serial.print("Voltage = ");
    Serial.print(analogRead(I1));
    Serial.println();
    lowestEnabledInput = 1;
  }
  if(analogRead(I0) > activeInputVoltage) {
    Serial.println("Input 0 active");
    Serial.print("Voltage = ");
    Serial.print(analogRead(I0));
    Serial.println();
    lowestEnabledInput = 0;
  }

  Serial.print("lowest enabled input = ");
  Serial.println(lowestEnabledInput);
  if(currentSelectedInput != lowestEnabledInput) {
    Serial.print("updating input, previous selection was ");
    Serial.println(currentSelectedInput);
    Serial.print("bit 0 ");
    Serial.println(bitRead(lowestEnabledInput, 0));
    Serial.print("bit 1 ");
    Serial.println(bitRead(lowestEnabledInput, 1));
    Serial.print("bit 2 ");
    Serial.println(bitRead(lowestEnabledInput, 2));
    //send the address of the input to use to gscart EXT
    digitalWrite(inAddr0, bitRead(lowestEnabledInput, 0));
    digitalWrite(inAddr1, bitRead(lowestEnabledInput, 1));
    digitalWrite(inAddr2, bitRead(lowestEnabledInput, 2));
    currentSelectedInput = lowestEnabledInput;
  }

  delay(500); //wait 0.5 second to poll again
}