Having a hell of a time with this arduino sketch. It's for this installation: http://www.andrewlb.com/2013/01/firesite-debug-view/ I think I'm getting there though. It is currently not quite working, but kind of working. I had misunderstood how the LPD8806 chip worked, switched over to only using the PWM pins. I'm going to have to split the sign…

firesiteSerial.ino

#include "LPD8806.h"
#include "SPI.h"

// Constants
const int NUMLIGHTS = 6;    // Number of lights per arm
const int NUMARMS = 3;      // Number of arms per light
const int LEDPERARM = 20;   // Number of lights
const int serialPin = 52;
const int testPin = 53;
bool connected;

int dataPins[NUMLIGHTS/**NUMARMS*/] = {
//    22,24,26,   // Light 0
//    28,30,32,   // Light 1
//    34,36,38,   // Light 2
//    40,42,44,   // Light 3
//    46,48,50,   // Light 4
//    4,6,8     // Light 5 
    2,
    4,
    6,
    8,
    10,
    12 
    
    
    
};

int clockPins[NUMLIGHTS/**NUMARMS*/] = {
//    23,25,27,   // Light 0
//    29,31,33,   // Light 1
//    35,37,39,   // Light 2
//    41,43,45,   // Light 3
//    47,49,51,   // Light 4
//    5,7,9     // Light 5    
    3,
    5,
    7,
    9,
    11,
    13 
    
    
};

// Light struct
typedef struct {
    int id; // The id must match that of the OF program
    int pwr; // 0-127 val, derived from OF float val
    LPD8806 strip[NUMARMS]; // The three strips
} Light;

Light Lights[NUMLIGHTS]; // Declare lights array


// Serial communication
String inString = ""; 
int curLight = 0;
//int curArm = 0;
int curPwr = 0;

void setup() {
    // Setup all lights and arms
    pinMode(testPin,OUTPUT);
    pinMode(serialPin,OUTPUT);
    for(int i=0;i<NUMLIGHTS;i++) {
        // Set up the Lights with the appropriate objects
        Lights[i].id = i;
        for(int a=0;a<NUMARMS;a++) {
            Lights[i].strip[a] = LPD8806(LEDPERARM, dataPins[i+a],   clockPins[i+a]);   
            Lights[i].strip[a].begin();
            Lights[i].strip[a].show();
            testStrip(&Lights[i].strip[a]);
            clearStrip(&Lights[i].strip[a]);
        }
    }
    
    // Start serial communication    
    Serial.begin(9600); connected = false;
    digitalWrite(testPin, HIGH); 
    delay(500);
}

void testStrip(LPD8806 * strip) {
    int i;
    for(i=0; i<strip->numPixels(); i++) { 
        strip->setPixelColor(i, 0);
    }
    strip->show(); 
    
    // Then display one pixel at a time:
    for(i=0; i<strip->numPixels(); i++) {
        strip->setPixelColor(i, getColor(127) ); // Set new pixel 'on'
        strip->show();              // Refresh LED states
        strip->setPixelColor(i, 0); // Erase pixel, but don't refresh!
        delay(25);
    }
    
    strip->show(); // Refresh to turn off last pixel
}

void clearStrip(LPD8806 * strip) {
    int i;
    
    for (i=0; i < strip->numPixels(); i++) {
        strip->setPixelColor(i, getColor(0));
        strip->show();
        delay(10);
    }
}
               
void loop() {
    if(connected) {
       digitalWrite(serialPin,HIGH); 
        digitalWrite(testPin, LOW); 
        for(int i=0;i<NUMLIGHTS;i++) {
            render(i);
        }
       digitalWrite(testPin, HIGH); 
   } else {
     digitalWrite(serialPin,LOW); 
     digitalWrite(testPin, HIGH); 
     for(int i=0;i<NUMLIGHTS;i++) {
         //Lights[i].pwr = 127;
        // render(i);
         for( int a=0;a<NUMARMS;a++) {
            testStrip(&Lights[i].strip[a]);
         }
     }        
   digitalWrite(testPin, LOW); 
   }
}                  
                                         
void render(uint32_t lightId) {
    int maxPower, minPower, ptr, ledStr, pwr;
    for(int a=0;a<NUMARMS;a++) {
        // Turn on
        for(int i=0;i<LEDPERARM;i++) {
            Lights[lightId].strip[a].setPixelColor(i,0);
            maxPower = i / LEDPERARM;
            minPower = 127 - (maxPower * (127-Lights[lightId].pwr));
          //  ptr = i + ( a * LEDPERARM );
            pwr = Lights[lightId].pwr;
            if(pwr > 0)
                Lights[lightId].strip[a].setPixelColor(i,getColor(pwr));
//            Lights[lightId].strip[a].show();
//            Lights[lightId].strip[a].setPixelColor(i,127);
        }
        Lights[lightId].strip[a].show();
        delay(10);
        // Turn all off
       
              
    }
//for(int a=0;a<NUMARMS;a++) {
//    for(int i=0;i<LEDPERARM;i++) {
//        Lights[lightId].strip[a].setPixelColor(i,0);
//    }
//    Lights[lightId].strip[a].show();
//}
    
     // holders for 10ms
}

// Derived from the LPD8806 lib
uint32_t getColor(int pwr) {    
    byte r,g,b;
    r = (byte)1-(pwr/2);
    b = (byte)(pwr/2);
    g = (byte)0;
/*    
    r = 127;
    b = 60;
    g = 0; */
    
    return ((uint32_t)(g | 0x80) << 16) |
    ((uint32_t)(r | 0x80) <<  8) |
    b | 0x80 ;
}
                                         
void parseSerial() {
    // Read serial input:
   int inChar;
   while(Serial.available()) {
       inChar = Serial.read();
    
    // Collecting the datas.
    if (isDigit(inChar)) {
        inString += (char)inChar; 
    }
    
    // Iterating through the lights
    if (inChar == ',') {
        Lights[curLight].pwr = inString.toInt();
        inString = ""; 
        curLight++;
    }
    
    // Last light
    if (inChar == '\n') {
        Lights[NUMLIGHTS-1].pwr = inString.toInt();
        inString = ""; 
        curLight = 0;
    }   
    Serial.println(curLight);
    Serial.println(Lights[curLight].pwr);
   }
}

void serialEvent() {
    connected = true;
    parseSerial();
}