IN-17 Bulb CrossFade Code Example.

Hi everyone!!

FYI, I did search the forum and I didn't see anyone talk about this one...

I am using the code from http://www.arduinix.com/Main/Downloads.htm for the 6 tube crossfade. There is something that doesn't make sense for me. I'm trying to learn how this actually works.

Here is the problem:

1) ledPin_a_1 is defined as pin 10 and initialized as OUTPUT but is never referenced anywhere else in the code.
2) ledPin_a_4 is defined as pin 13 but is NOT initialized as OUTPUT but it is used in the DisplayFadeNumberString function.
3) in the DisplayFadeNumberString, ledPin_a_4 IS used even though ledPin_a_4 is never initialized as an OUTPUT.
4) if this is a 6 tube clock code, why do we need 4 anodes?

code snippets below

Thanks!
Joe

Code:

// anode pins
int ledPin_a_1 = 10;
int ledPin_a_2 = 11;
int ledPin_a_3 = 12;
int ledPin_a_4 = 13;

In setup:
pinMode(ledPin_a_1, OUTPUT);
  pinMode(ledPin_a_2, OUTPUT);
  pinMode(ledPin_a_3, OUTPUT);

void DisplayFadeNumberString()
{

  // Anode channel 1 - numerals 0,3
  SetSN74141Chips(currNumberArray[0],currNumberArray[3]);
  digitalWrite(ledPin_a_2, HIGH);
  delay(NumberArrayFadeOutValue[0]);
  SetSN74141Chips(NumberArray[0],NumberArray[3]);
  delay(NumberArrayFadeInValue[0]);
  digitalWrite(ledPin_a_2, LOW);

  // Anode channel 2 - numerals 1,4
  SetSN74141Chips(currNumberArray[1],currNumberArray[4]);
  digitalWrite(ledPin_a_3, HIGH);
  delay(NumberArrayFadeOutValue[1]);
  SetSN74141Chips(NumberArray[1],NumberArray[4]);
  delay(NumberArrayFadeInValue[1]);
  digitalWrite(ledPin_a_3, LOW);

   // Anode channel 3 - numerals 2,5
  SetSN74141Chips(currNumberArray[2],currNumberArray[5]);
  digitalWrite(ledPin_a_4, HIGH);
  delay(NumberArrayFadeOutValue[2]);
  SetSN74141Chips(NumberArray[2],NumberArray[5]);
  delay(NumberArrayFadeInValue[2]);
  digitalWrite(ledPin_a_4, LOW);