//  Arduino analog input 5 - I2C SCL
//  Arduino analog input 4 - I2C SDA

#include <Wire.h>

int set1StartAddress = 0x20;
int set2StartAddress = 0x38;

//byte oldModuleId = 0;
int oldModuleId = 0;

byte data;  // the data that presents at the seial port
int moduleNo; // modules 0-12
int ledNo; // leds 0-7
byte moduleId; //this is a byte representation of fixed "set" address + module number (0-12)
byte ledByte; // this is

int LEDPin = 13;

void setup() {

  pinMode(LEDPin, OUTPUT);    // set pin 13 to be an output

  // initialize the serial communication:
  Serial.begin(9600);
  Wire.begin();

  //flash flash: lets us know the program is running
  digitalWrite(LEDPin, HIGH);
  delay(250);
  digitalWrite(LEDPin, LOW);
  delay(250);
  digitalWrite(LEDPin, HIGH);
  delay(250);
  digitalWrite(LEDPin, LOW);
  delay(250);

  //turn set 1 off
  for(int i = 0; i<8; i++) {
    moduleId = byte(set1StartAddress + i);
    Wire.beginTransmission(moduleId);
    Wire.write(0);
    Wire.endTransmission();
  }

  //turn set 2 off
  for(int i = 0; i<5; i++) {
    moduleId = byte(set2StartAddress + i);
    Wire.beginTransmission(moduleId);
    Wire.write(0);
    Wire.endTransmission();
  }
}

//Waits for a number 0 - 100 from processing
void loop(){

  //check for available byte and read it
  if(Serial.available() > 0) {

    //serial working feedback
    digitalWrite(LEDPin, HIGH);

    data = Serial.read();

    // gives module number 0-12 (sans remainder)
    moduleNo = int(data) / 8;
    // gives 1 of 8 LEDs 0-7 (using remainder)
    ledNo = int(data) % 8;

    //which I2c module set are we addressing?
    if(moduleNo < 8) {
      moduleId = byte(set1StartAddress + moduleNo);
    }
    else {
      moduleId = byte(set2StartAddress + moduleNo - 8);
    }

    //set LED byte
    ledByte = byte(1 << ledNo);



    //Switch old module off
    Wire.beginTransmission(oldModuleId);
    Wire.write(0);
    Wire.endTransmission();

    //Switch new LED on
    Wire.beginTransmission(moduleId);
    Wire.write(ledByte);
    Wire.endTransmission();

    oldModuleId = moduleId;

  }
  digitalWrite(LEDPin, LOW);
}