SMS Relay

#include <SoftwareSerial.h>

char input[64]; // variable to store the incoming characters

SoftwareSerial debug(4, 5);  //RX, TX
const int Relay = 8;

void setup() {
  debug.begin(9600);
  debug.println("Device Initializing...");

  pinMode(Relay, OUTPUT);
  memset(input, 0, 64); //clear input buffer

  digitalWrite(Relay, LOW);

  // wake up the GSM shield
  Serial.begin(9600);

  delay(2000);
  Serial.println("AT+CMGF=1"); // set SMS mode to text
  delay(100);
  Serial.println("AT+CNMI=2,2,0,0,0");
  // just to get a notification when SMS arrives &direct out SMS upon receipt to the GSM serial out
  delay(100);
}

void executeCommand(){
  if(!strcmp(input, "$a0")){
      debug.println("Relay OFF");
      digitalWrite(Relay, LOW);
  } else if(!strcmp(input, "$a1")) {
    debug.println("Relay ON");
    digitalWrite(Relay, HIGH);
  } else {
    debug.println(strcat("Unknown Command: ", input));
  }
  Serial.println("AT+CMGD=1,4"); // delete all SMS
  delay(1000);
}

void loop(){
  //If a character comes in from the GSM...

  int i = 0;
  while(Serial.available()){
    char c = Serial.read();
    input[i++] = c;
    delay(12);
  }

  if(i){
    input[i++] = 0; //null terminate our string
    executeCommand();
    i = 0;
  }
}