A transmitter and receiver circuit to turn on a laser diode

/* 
Author: Will Forfang 
Corresponding Email: W.Forfang@gmail.com
Date: 6/4/2013
This program samples an analog voltage signal (sensor output) and stores the last N samples in a buffer.
It computes the average of samples in the buffer, converts the average to an array of characters, and then
transmit the array via RF to a receiver.


*/

// Global area

#include <VirtualWire.h> //Make sure this library is installed in your 'Energia\hardware\msp430\libraries' directory.

const int transmit_pin = 9;    //pin 9 on launchpad is P2_1
const int receive_pin = 2;     //P1_0
const int transmit_en_pin = 3; //P1_1
const int xpin = 5;            // output of accel, or temp sensor goes to analog input 3 (P1_3) on launchpad

const int frameLength = 120; //number of samples with which to calculate statistics
int frame [frameLength]; //initialize
float sum = 0; //initialize 
char avgChar[7]; //initialize

void setup(){ 
  
  // Initialise the IO and ISR
  vw_set_tx_pin(transmit_pin);
  vw_set_rx_pin(receive_pin);
  vw_set_ptt_pin(transmit_en_pin);
  vw_set_ptt_inverted(true); // Required for DR3100
  vw_setup(2000);	 // Bits per sec
  Serial.begin( 9600 ); }

void loop(){ 
  Serial.println("test"); //for debugging
sum = 0;
byte count = 0;
for (count = 0; count<frameLength; count++)
{
  int currentValue = analogRead(xpin);
  frame[count] = analogRead(xpin); //frame of samples; not used yet
  sum = sum + currentValue;
}
 
  //compute average of time-domain samples in 'frame'
  int avg = sum / frameLength;
  //Convert integer to char array for transmission
  itoa(avg,avgChar,7);
    
  
 // vw_send((uint8_t*)avgChar, 7);
  vw_send((uint8_t *)avgChar, strlen(avgChar));
  vw_wait_tx(); // Wait until the whole message is gone

  Serial.print("temp:"); 
  Serial.print("\t"); //tab
  Serial.print(avgChar);
  Serial.print("\n"); //new line
  
}