== Modify Huey the Chameleon ==
Note, that this script is pretty complicated due to the need to read accurate values from the color sensor. This is embedded in the read_color() function. This is almost certainly the hardest of the available lab projects, so if you're intimidated, you may want to try a different one.

Huey contains:

 * a switch on pin 5
 * a color sensor module using pins 8-12, no library for this
 * an 8 LED strip, NOT NeoPixels, on pins 2 and 3
 * note that 2 of the leds are supposed to be positioned behind the eyes, but I think one has slipped out of place...

To use this, you will need to download and install the [[https://github.com/adafruit/LPD8806|LPD8806 library]] to drive the LED strip.

Here is Huey's current sketch:
{{{
#include "LPD8806.h"
#include "SPI.h"
// Number of RGB LEDs in strand:
int nLEDs = 8;

int dataPin  = 2;
int clockPin = 3;

// First parameter is the number of LEDs in the strand.  The LED strips
// are 32 LEDs per meter but you can extend or cut the strip.  Next two
// parameters are SPI data and clock pins:
LPD8806 strip = LPD8806(nLEDs, dataPin, clockPin);

void setup() {
  // Start up the LED strip
  strip.begin();

  // Update the strip, to start they are all 'off'
  strip.show();

  pinMode(5,OUTPUT);  // Using 5/6 combined for the pushbutton switch
  pinMode(6,INPUT_PULLUP);   // output is just to avoid another solder connection

  pinMode(8,OUTPUT); // 8 & 9 define color (RBCG)
  pinMode(9,OUTPUT); 
  pinMode(10,OUTPUT); // 10 & 11 define amplification (off, .02, .2, 1.0)
  pinMode(11,OUTPUT);
  pinMode(12,INPUT);  // color out, frequency encoded, ~16khz max

  digitalWrite(5,LOW);

  digitalWrite(10,HIGH);
  digitalWrite(11,HIGH);

}

int lp=1;
unsigned long cm[4] = {0,0,0,0};   // color max values
//unsigned long cmi[4] = {500,500,500,500};  // color min values
unsigned long cmi[4] = {0,0,0,0};  // color min values

const uint32_t read_color(float gamma) {
  int c,i;
  unsigned long cs[4];
  
  // This block reads the color values from the hardware sensor and keeps track of min/max
  for (c=0; c<4; c++) {
    digitalWrite(9,(c&1)?HIGH:LOW);
    digitalWrite(8,(c&2)?HIGH:LOW);
    
    for (i=0; i<4; i++) pulseIn(12,LOW,100000); //wait in case it takes time to adjust
    
    unsigned long av=0;
    for (i=0; i<10; i++) {
      av+=pulseIn(12,HIGH,100000);
    }
    av++;  // just in case it's zero
    cs[c]=200000/av;  // 320 should be the max value we get here
    if (cs[c]>cm[c]) cm[c]=cs[c];    // keep track of the maximum for each color
    if (cs[c]<cmi[c]) cmi[c]=cs[c];  // and the minimum
  }

  float r2,g2,b2,c2;
  int s;
   r2=(cs[0]-cmi[0])/(float)(cm[0]-cmi[0]);
   g2=(cs[3]-cmi[3])/(float)(cm[3]-cmi[3]);
   b2=(cs[1]-cmi[1])/(float)(cm[1]-cmi[1]);
   c2=(cs[2]-cmi[2])/(float)(cm[2]-cmi[2]);
  
  r2=pow(r2,gamma);
  g2=pow(g2,gamma);
  b2=pow(b2,gamma);
  s=(int)(127*c2);
  
  float l=r2+g2+b2;
   
  r2/=l;
  g2/=l;
  b2/=l;
   
   return strip.Color((int)(r2*s),(int)(g2*s),(int)(b2*s));
}

uint32_t cary[7] = { 0,0,0,0,0,0,0 };
int cycle = 0;

uint32_t   red(uint32_t color) { return (color>>8)&127; }
uint32_t  blue(uint32_t color) { return color&127; }
uint32_t green(uint32_t color) { return (color>>16)&127; }
int ldr=1,on=1;

void loop() {
  uint32_t c;
  int i;
  
  // Draw the back if in "on" mode
  if (on) {
    // every 10 cycles we shift back
    if (cycle==0) {
      for (i=0; i<6; i++) cary[i]=cary[i+1];
      cary[6]=read_color(3.0);
    }
  
    // draw the interpolated colors
    for (i=0; i<6; i++) 
      strip.setPixelColor(i,(red(cary[i])*(9-cycle)+red(cary[i+1])*cycle)/9,(green(cary[i])*(9-cycle)+green(cary[i+1])*cycle)/9,(blue(cary[i])*(9-cycle)+blue(cary[i+1])*cycle)/9 );
  }
  
  int dr=digitalRead(6);
  if (dr==0 && ldr==1) on^=1;
 
  // draw the eyes in the currently seen color
  c=read_color(3.0);
  if (dr) { strip.setPixelColor(6,c); strip.setPixelColor(7,c); }
  else { strip.setPixelColor(6,strip.Color(0,0,0)); strip.setPixelColor(7,strip.Color(0,0,0)); }
   
  strip.show();
  delay(30);
  
  ldr=dr;
  cycle=(cycle+1)%10;
}
}}}
 
 * You might want to try compiling the stock sketch first and make sure you can get it to work.
 * Make Huey do something interesting

That's it. You're done. Nothing to turn in (though if you made Huey do something particularly interesting, you could send me a copy of the sketch).