/*********************************************************************
SCULLCOM Hobby Electronics
Simple GPS System
Using Arduino Pro Mini + OLED 128x64 display + GPS Module
*********************************************************************/

#include <SPI.h>                      //Serial Peripheral Interface (SPI) library for synchronous serial data protocol
#include <Wire.h>                     //Wire library used for I2C communication: Arduino Pro Mini pins used = A4 (SDA) and A5 (SCL)
#include <Adafruit_GFX.h>             //Adafruit graphic display library used for the OLED display
#include <Adafruit_SSD1306.h>         //Adafruit driver for OLED

#include <SoftwareSerial.h>           //SoftwareSerial library used to allow serial communication on other digital pins (i.e. Pins 3 & 4 for the this GPS project)
#include <TinyGPS.h>                  //GPS Library used to read the data from GPS Module

#define OLED_RESET 5
Adafruit_SSD1306 display(OLED_RESET);

TinyGPS gps;                          //Create the TinyGPS object, giving it a name of your choice (here we use the name gps)
SoftwareSerial nss(3, 4);             //set sotfware serial communications to arduino ports 3 and 4 (TX = 3 and RX = 4)

void setup()   {                  
   nss.begin(9600);
  
  unsigned long age, date, time, chars = 0;

  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);  // initialize the OLED and set the I2C address to 0x3C (for the 128x64 OLED) 
  
  display.clearDisplay();             //Clear display buffer.

  display.setTextSize(2);             //set text size to 2 (large)
  display.setTextColor(WHITE);
  display.setCursor(0,0);             //set text start position to column=0 and row=0
  display.print("SCULLCOM");          //print "SCULLCOM" to display
  
  display.setTextSize(1);             //set text size to 1 (small)
  display.setCursor(0,18);            //set text start position to column=0 and row=18
  display.print("GPS SYSTEM");        //print "GPS SYSTEM" to display
  
  display.setCursor(0,30);            //set text start position to column=0 and row=30
  display.setTextColor(BLACK, WHITE); // 'inverted' text
  display.print("INITIALISING .....");//print "INITIALISING ....." to display
  display.setCursor(0,40);            //set text start position to column=0 and row=40
  display.setTextColor(WHITE);        //
  display.print("Trying to locate GPS satellites ...");  //print "Trying to locate GPS satellites ..." to display
  
  display.setCursor(0,57);            //set text start position to column=0 and row=57
  display.print("Please Wait");       //print "Please Wait" to display
  
  display.display();                  //update OLED with new display data
  delay(1000);                        //short delay
  display.clearDisplay();             //clear display
}


//MAIN PROGRAMME LOOP
void loop() {

bool newdata = false;
  unsigned long start = millis();
  while(millis() - start < 1000){    // Every 1 seconds we print an update
    if (feedgps())
      newdata = true;
  }
  if (newdata)
  { 
    gpsdump(gps);
  }
}
 
 
//PRINT GPS DATA TO OLED DISPLAY
void gpsdump(TinyGPS &gps)
{  
  print_date(gps);                  //print date and time at top of OLED display
  
  float flat, flon, falt;

  display.clearDisplay();
  
  display.setTextSize(1);           //set text size to 1
  display.setTextColor(WHITE);      //
  display.setCursor(0,0);           //set text start position for date and time (row = 0, column =0)
  print_date(gps);                  //prints date and time on top line to OLED
  
  gps.f_get_position(&flat, &flon); //retrieves latitude and longditude data
  display.setCursor(0,20);          //set text start position to column=0 and row=20
  display.print("Altitude : ");     //print "Altitude" : to display
  display.println(gps.f_altitude());//print altitude data to display
  display.setCursor(100,20);        //set text start position to column=100 and row=20
  display.println("m");             //print "m" to display
  
  display.setCursor(0,30);          //set text start position to column=0 and row=30
  display.print("Sats     : ");     //print "Sats    :" to display
  display.println(gps.satellites());//print number of satellites detected to display
  
  display.setCursor(0,40);          //set text start position to column=0 and row=40
  display.print("latitude : ");     //print "latitude :" to display
  display.println(flat,6);          //print latitude data to display up to 6 decimal places
  
  display.setCursor(0,50);          //set text start position to column=0 and row=50
  display.print("longitude: ");     //print "longitude:" to display
  display.println(flon,6);          //print longitude data to display up to 6 decimal places

  display.display();                //update OLED display
}


//TEST FOR NEW DATA FROM THE GPS MODULE
bool feedgps()
{
  while (nss.available())
  {
    if (gps.encode(nss.read()))    //Each byte of NEMA data must be giving to TinyGPS by using encode(). True is returned when new data has been fully decoded and can be used
      return true;
  }
  return false;
} 


//GET DATE AND TIME FOR DISPLAY
static void print_date(TinyGPS &gps)
{
  int year;
  byte month, day, hour, minute, second, hundredths;
  unsigned long age;
  gps.crack_datetime(&year, &month, &day, &hour, &minute, &second);
  {
    char sz[32];
    sprintf(sz, "%02d/%02d/%02d  %02d:%02d:%02d",
        day, month, year, hour, minute, second);    
    display.print(sz);                      //Print date and time to OLED
  }

}