LED christmas tree

Project: LED christmas tree
Featured:
State	Active
Members	Vicarious, Xopr
GitHub	No GitHub project defined. Add your project here.
Description	Blinken lights!
Picture

synopsis

Create a christmas tree out of cartboard, leds, some RJ45 wire, tiny experiment print, headers, solder, Scotch-tape, a brown plastic instant-coffee container and an arduino.

I hereby declare freedom of firmware for the tree; change to whatever you want it; this was just a kick-start.

implementation

Since the tree was already made two years ago, but the code (and/or Arduino) got lost, Xopr took his Andon light arduino, and did an ugly rush job on making the leds identifiable.

After identifying which port pin was which LED, I wrote some shifting logic to be able to call setLed( x, y ) and clearLed( x, y ).

Actually, I think writing about it on the wiki costs more time than actually pimping the tree, so here it is.

pics

Pics (or vid) or it didn't happen!

Since the video plugin still doesn't work, here a direct link: Media:Christmas tree and message ticker.mov.

code

The current code running is the one pasted here (with some preparations on doing PWM) Arduino code (portable to plain avr-gcc):

void setup()
{
  // Set tree pins as output
  DDRB = B11110000;
  DDRH = B01111000;
  DDRE = B00111010;
  DDRG = B00100000;

  // All lights on
  PORTB = B11110000;
  PORTE = B00111010;
  PORTG = B00100000;
  PORTH = B01111000;
  delay( 2000 );

  // All lights off
  PORTB = 0;
  PORTE = 0;
  PORTG = 0;
  PORTH = 0;
  delay( 1000 );
}

/*
  // Mapping of the pins on the tree are as followed (reverse-lookup pins from Arduino mega 1280):
  // {Port-and-pin-number}: {light-on-the-tree} {port-as-index-number,pin-number}: {resulting-mapping-index}
  PORTB7: top  0,7: 7
  PORTB6: 3a   0,6: 6
  PORTB5: 3c   0,5: 5
  PORTB4: 3b   0,4: 4

  PORTH6: 3d   3,6: 30
  PORTH5: 2b   3,5: 29
  PORTH4: 2c   3,4: 28
  PORTH3: 2d   3,3: 27

  PORTE5: 1d   1,5: 13
  PORTE4: 1a   1,4: 12
  PORTE3: 2a   1,3: 11
  PORTE2: 1b   1,1: 9

  PORTG5: 1c   2,5: 19
*/

// Mapping
byte g_mappedTree[4][4] = {
  { 12,  9, 21, 13 }, // Row 1, Da Syntax helped me calculating the number 21 ;)
  { 11, 29, 28, 27 }, // Row 2
  {  6,  4,  5, 30 }, // Row 3
  {  7,  7,  7,  7 }, // Top; yes it is only one led, so one pin
};

void loop()
{
  for ( byte n = 0; n < 10; n++ )
    horizontalBlink();
  for ( byte n = 0; n < 10; n++ )
    verticalBlink();
  for ( byte n = 0; n < 100; n++ )
    randomBlink();
}

void horizontalBlink()
{
  // Add vertical strips of light: switch on clock wise
  // When all lights are on, switch them off clock wise

  // Horizontal
  for ( byte x = 0; x < 4; x++ )
  {
    // Vertical
    for ( byte y = 0; y < 4; y++ )
    {
      setLed( x, y );
    }
    delay( 100 );
  }
  // Horizontal
  for ( byte x = 0; x < 4; x++ )
  {
    // Vertical
    for ( byte y = 0; y < 4; y++ )
    {
      clearLed( x, y );
    }
    delay( 100 );
  }
 
}

void verticalBlink()
{
  // In four steps, light a ring from bottom to top
  // When all lights are on, switch them off bottom to top

  // Vertical
  for ( byte y = 0; y < 4; y++ )
  {
   // Horizontal
    for ( byte x = 0; x < 4; x++ )
    {
      setLed( x, y );
    }
    delay( 100 );
  }
  // Vertical
  for ( byte y = 0; y < 4; y++ )
  {
   // Horizontal
    for ( byte x = 0; x < 4; x++ )
    {
      //setLed( x, y );
      clearLed( x, y );
    }
    delay( 100 );
  }
 
}

void randomBlink()
{
  // Pick a random row and column, a random state,
  // and apply that state to the indexed led
  // This is somewhat similar as the original tree had

  byte x = random( 4 );
  byte y = random( 4 );
  if ( random( 2 ) )
    setLed( x, y );
  else
    clearLed( x, y );
  delay( 100 );
}


void setLed( byte _x, byte _y )
{
  // This function does the led magic: it deduces the bit and port index from the mapping number
  // like this: xxxppbbb, there the lowest 3 bits are values 0-7, indicating the bit we're after
  // and the two bits after that determine the port

  // Yes, I could use the arduino port index, but this is faster

  // Fetch the mapping index for the given coordinate
  byte mappedPort = g_mappedTree[ _y ][ _x ];
  // Determine the bit index (lower three bits)
  byte shiftBit = mappedPort & 7;

  // Find which port it is (shift out the lower three bits and get the index)
  // And set the given bit
  switch ( mappedPort >> 3 )
  {
    case 0:
      PORTB |= (1 << shiftBit);
      break;
      
    case 1:
      PORTE |= (1 << shiftBit);
      break;
      
    case 2:
      PORTG |= (1 << shiftBit);
      break;

    case 3:
      PORTH |= (1 << shiftBit);
      break;
  }
}

void clearLed( byte _x, byte _y )
{
  // Same as setLed, except for the port bit banging
  // Yes, these functions can be combined, but the whole program was a quick hack

  // Fetch the mapping index for the given coordinate
  byte mappedPort = g_mappedTree[ _y ][ _x ];
  // Determine the bit index (lower three bits)
  byte shiftBit = mappedPort & 7;

  // Find which port it is (shift out the lower three bits and get the index)
  // And clear the given bit
  switch ( mappedPort >> 3 )
  {
    case 0:
      PORTB &= ~(1 << shiftBit);
      break;
      
    case 1:
      PORTE &= ~(1 << shiftBit);
      break;
      
    case 2:
      PORTG &= ~(1 << shiftBit);
      break;

    case 3:
      PORTH &= ~(1 << shiftBit);
      break;

  }
}