 #include <SoftwareSerial.h>
 #include <SabertoothSimplified.h>
 #include <TinyGPS++.h>
+#include <PID_v1.h>
 
 SoftwareSerial SWSerial(NOT_A_PIN, 8); // RX on no pin (unused), TX on pin 11 (to S1).
 SabertoothSimplified ST(SWSerial); // Use SWSerial as the serial port.

  SWSerial.begin(9600);
  // Initialize serial communications at 9600 bps:
  Serial.begin(19200);
}

void SerialEvent() {

long lastWriteTime = 0;

TinyGPSPlus nmea;
TinyGPSCustom pwm(nmea, "ORPWM", 1);
TinyGPSCustom roll(nmea, "ORPOS", 1);
TinyGPSCustom elevation(nmea, "ORPOS", 2);
TinyGPSCustom bearing(nmea, "ORPOS", 3);

//Define Variables we'll be connecting to
double Setpoint, Input, Output;

//Specify the links and initial tuning parameters
PID myPID(&Input, &Output, &Setpoint,10,0,50, DIRECT);

void setup()
{
