#include <U8g2lib.h>
#define SDA_1 15
#define SCL_1 16
#define SDA_2 17
#define SCL_2 18

U8G2_SSD1315_128X64_NONAME_1_HW_I2C(U8G2_R1)

#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_HMC5883_U.h>

/* Assign a unique ID to this sensor at the same time */
Adafruit_HMC5883_Unified mag = Adafruit_HMC5883_Unified(12345);

  #define GPS_BAUD 9600
#define RXD2 16
#define TXD2 17
// Create an instance of the HardwareSerial class for Serial 2
HardwareSerial gpsSerial(2);




void setup() {

  u8g2.begin();
  gpsSerial.begin(GPS_BAUD, SERIAL_8N1, RXD2, TXD2);


}

void loop() {
  // put your main code here, to run repeatedly:
  
  sensors_event_t event; 
  mag.getEvent(&event);

  while (gpsSerial.available() > 0){
    // get the byte data from the GPS
    char gpsData = gpsSerial.read();
    Serial.print(gpsData);
  }
  delay(1000);
  Serial.println("-------------------------------");

  /* Display some basic information on this sensor */
  displaySensorDetails();
   gpsSerial.begin(GPS_BAUD, SERIAL_8N1, RXD2, TXD2);
  float heading = atan2(event.magnetic.y, event.magnetic.x);
  
  // Once you have your heading, you must then add your 'Declination Angle', which is the 'Error' of the magnetic field in your location.
  // Find yours here: http://www.magnetic-declination.com/
  // Mine is: -13* 2' W, which is ~13 Degrees, or (which we need) 0.22 radians
  // If you cannot find your Declination, comment out these two lines, your compass will be slightly off.
  float declinationAngle = 0.22;
  heading += declinationAngle;
  
  // Correct for when signs are reversed.
  if(heading < 0)
    heading += 2*PI;
    
  // Check for wrap due to addition of declination.
  if(heading > 2*PI)
    heading -= 2*PI;
   
  // Convert radians to degrees for readability.
  float headingDegrees = heading * 180/M_PI; 
}