Our “tree of knowledge” has a new program. The colour change is  more slowly (gives a more intensive experience :), the short range of red colours is extended by passing red even more slowly, and the tree is now communicative: the lights turn all red and do not turn out when someone appoaches. The arduino code is below.

#include <Wire.h>
/*
 * Tree Of Knowledge --
 * Tree with 30 BlinkM led modules
 * The modules are connected using I2C. The blinkM routines are taken from
 * the blinkM website: http://thingm.com/
 * Tree connections to Arduino
 * PWR - -- gnd -- blue -- Gnd
 * PWR + -- +5V -- red   -- 5V
 * I2C d -- SDA -- yellow -- Analog In 4
 * I2C c -- SCK -- green  -- Analog In 5
 *
 * original version from E. Dertien with changes from A. Mader, 3 june 2009
 */

#include "Wire.h"
#include "BlinkM_funcs.h"
#define BLINKM_ARDUINO_POWERED 1
int hue[32], stap, sense;      // each ball has now its own colour variable
int sensePin=0;

void setup()
{
    BlinkM_begin();
    Serial.begin(9600);
    BlinkM_stopScript(0);  // addr 0 means to all blinkm's. This command stops pre-programmed sequences.
    for (int ball=1; ball<31; ball++) //check all balls visually
    {
     hue[ball] = 3*ball+100;
     BlinkM_setFadeSpeed( ball, 255 );
     BlinkM_fadeToHSB( ball, 25, 0xff, 0xff );
     BlinkM_fadeToHSB(ball-1, 0x00, 0xff, 0x00 );
     delay(100); 
    }  
}

void loop()
{
 int ball;
 sense = analogRead(sensePin);
 if (sense>350) 
  { // case: someone is approaching the tree, the apples turn red
   for(ball=1; ball<31; ball++)
   {hue[ball]=int(ball-25)%255;       // this is approximately the range of red colours
   BlinkM_fadeToHSB( ball, hue[ball], 0xff, 0xff );};
  }
 else
  { // case: stand-alone tree where colours are changing
  for(ball=1; ball<31; ball++)
  {if ( (hue[ball]>235) or (hue[ball]<25)) {stap=1; delay(10);} else {stap=3;}; 
                                      // in the red range the colour cange is by step of 1, 
    hue[ball]=(hue[ball]+stap)%255;
    BlinkM_setFadeSpeed( ball, 1 );   // this is a slow fade 
    BlinkM_fadeToHSB( ball, hue[ball], 0xff, 0xff);
  } }
  //Serial.println(sense);
  delay(400);
}

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