Building Your Own AVR / Arduino Internet of Things (IoT) Development Board Part 2

This is part 2 in a 5 part series where we build our own AVR / Arduino Internet of Things (IoT) development board, yay! In this part we add the Arduino bootloader to our Atmega 328p as well as build and test a prototype of our design.

BLE Micro Shield Eagle Files 1.0 version (use at your own risk):
https://dl.dropboxusercontent.com/u/26591541/BLE%20Shield.zip


//*******************Arduino Code**********************************************
/*
  This sketch is part of a video tutorial on the ForceTronics YouTube Channel for Building Your AVR/Arduino IoT Development Board 
  which uses a Atmega 328p and a Bluetooth low energy module. 
  The bluetooth module is connected to an Arduino and the Arduino is connected to an LED. 

  This code is in the public domain.
 */

// Pin 13 has a LED connected to it
int led = 13;

// the setup routine runs once when you press reset:
void setup() {
  
  Serial.begin(115200);
  // initialize the digital pin as an output and set it low initially
  pinMode(led, OUTPUT);
  digitalWrite(led, LOW);
}

// the loop routine runs over and over again forever:
void loop() {
  delay(30);
  String t; //create an empty string to store messages from Android
  while(Serial.available()) { //keep reading bytes while they are still more in the buffer
    t += (char)Serial.read(); //read byte, convert to char, and append it to string
  }
  
  if(t.length()) { //if string is not empty do the following
    if(t == "on") { //if the string is equal to "on" then turn LED on
      digitalWrite(led, HIGH); //Set digital pin to high to turn LED on
      Serial.write("LED is on"); //Tell the Android app that the LED was turned on
    }
    else if (t == "off") { 
      digitalWrite(led, LOW);  
      Serial.write("LED is off");
    } // turn the LED off by making the voltage LOW
  }
}