LoRaWAN-Signal-Mapping/iot/main/gps.h

#pragma once

#include <SoftwareSerial.h>

#include "settings.h"

// A lightweight struct to hold location information.
// TinyGPS++ actually uses a *ton* of RAM so we can't keep the instance around as a global variable
// FUTURE: Rewrite this to use TinyGPS's integer system instead?
struct GPSLocation {
	float lat;
	float lng;
	#ifdef SD_DEBUG_ENABLED
	char time[20];
	#endif
};

/**
 * Initialises the connection to the GPS device.
 */
SoftwareSerial gps_begin();

/**
 * Fetches new data from the GPS module.
 * May take a moment, as the GPS device needs time to acquire a satellite fix.
 */
GPSLocation gps_fetch();

/**
 * Ends the connection to the GPS device and puts it to sleep in order to save 
 * power.
 * Note that the GPS device is connected directly to the power management 
 * system and so doesn't get turned off after each measurement, as it takes 
 * ~30s to reacquire a lock when it first starts up - hence why we put it to 
 * sleep instead.
 * TODO: Connect the gps module to the timed power rail instead, as its; got an onboard battery.
 */
void gps_end(SoftwareSerial gps);