Arduino LEDs

gistfile1.txt

// Declare the pins backwards, so we can use pointer
// arithmetic without finding the end of the array
int ledPins[] = {9,8,7,6,5,4,3,2};
int pinCount = 8;
int highValue = 2 << (pinCount - 1);

void setup() {                
  // initialize the digital pins as an output.
  for (int i = 0 ; i < pinCount; i++) { 
    pinMode(ledPins[i], OUTPUT);
  }
}

void loop() {
  // Binary counter
  for (int i = 0 ; i < 255; i++) { 
    lightPins(ledPins, 7, i, 100);
  }
  lightPins(ledPins, pinCount, 0, 1000);
  
  // Left retract
  int n = 0;
  for (int pin = pinCount * 2; pin > 0; pin--) {
    if (pin >= pinCount) {
      n = highValue + (n >> 1);
     } else {
       n = n << 1;
     }
     lightPins(ledPins, pinCount, n, 100);
  }
  lightPins(ledPins, pinCount, 0, 1000);
  
  // Left pass through
  for (int pin = pinCount * 2; pin > 0; pin--) {
    if (pin > pinCount) {
      n = highValue + (n >> 1);
    } else {
      n = n >> 1;
    }
    lightPins(ledPins, pinCount, n, 100);
  }
  lightPins(ledPins, pinCount, 0, 1000);
  
  // Right retract
  for (int pin = pinCount * 2; pin > 0; pin--) {
    if (pin > pinCount) {
      n = 1 + (n << 1);
    } else {
      n = n >> 1;
    }
    lightPins(ledPins, pinCount, n, 100);
  }
  lightPins(ledPins, pinCount, 0, 1000);
  
  // Right pass through
  for (int pin = pinCount * 2; pin > 0; pin--) {
    if (pin > pinCount) {
      n = 1 + (n << 1);
    } else {
      n = n << 1;
    }
    lightPins(ledPins, pinCount, n, 100);
  }
  lightPins(ledPins, pinCount, 0, 1000);
  
  // Random numbers
  for (int i = 0; i < 10; i++) {
    lightPins(ledPins, pinCount, (rand() % (2 << pinCount)), 1000);
  }  
  lightPins(ledPins, pinCount, 0, 1000);

}

void lightPins(int* pins, int count, int pattern, int duration) {
  digitalWrite(*pins++, pattern % 2);
  if (count-- == 1) {
    delay(duration);
    return;
  }
  lightPins(pins++, count, pattern >> 1, duration);
}