Implement GPS & microSD card functionality, but it's not finished or tested yet.

iot/main/gps.c

@@ -1,6 +0,0 @@
-#include "gps.h"
-#include "settings.h"
-
-void gps_begin() {
-	serial_gps.begin(BAUD_GPS);
-}

iot/main/gps.cpp

@@ -0,0 +1,27 @@
+#include "gps.h"
+#include "settings.h"
+
+void gps_begin() {
+	serial_gps.begin(BAUD_GPS);
+}
+
+TinyGPSLocation gps_location() {
+	Serial.print("[gps] Getting location: ");
+	while(serial_gps.available() > 0) {
+		if(!gps.encode(serial_gps.read()))
+			continue;
+		
+		if(!gps.location.isValid() || gis.location.isUpdated()) {
+			Serial.print(".");
+			delay(100);
+			continue;
+		}
+		
+		Serial.println("ok");
+		return gps.location;
+	}
+}
+
+void gps_end() {
+	Serial.println(F("[warning] Putting the GPS device to sleep isn't implemented yet."));
+}

iot/main/gps.h

@@ -22,4 +22,14 @@ void gps_begin();
  * May take a moment, as the GPS device needs time to acquire a satellite fix.
  * @return TinyGPSLocation	The current location.
  */
-TinyGPSLocation get_location();
+TinyGPSLocation gps_location();
+
+/**
+ * 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.
+ */
+void gps_end();

iot/main/main.ino

@@ -1,4 +1,5 @@
 #include <Arduino.h>
+#include <TinyGPS++.h>
 
 #include "settings.h"
 #include "gps.h"
@@ -7,10 +8,13 @@ void setup() {
 	Serial.begin(BAUD_PC);
 	
 	gps_begin();
+	TinyGPSLocation loc = get_location();
+	gps_end();
+	
+	Serial.print("[main] Location: ("); Serial.print(loc.longitude()); Serial.print(", "); Serial.print(loc.latitude()); Serial.println();
 	
 	
 	
-	get_location();
 }
 
 void loop() {

iot/main/random.h

@@ -0,0 +1 @@
+#pragma once

iot/main/settings.h

@@ -29,5 +29,7 @@
 ////////// microSD Card //////////
 //////////////////////////////////
 
-// 
+// The chip select pin that activates the connection to the microSD card over SPI.
 #define	PIN_SD_SPI_CHIP_SELECT	3
+
+#define SD_FILENAME	"data.tsv"

iot/main/storage.c

@@ -1,17 +0,0 @@
-#include <Arduino.h>
-#include <SD.h>
-
-#include "settings.h"
-
-void store_init() {
-	pinMode(PIN_SPI_CHIP_SELECT, OUTPUT);
-	
-	if(!SD.begin(PIN_SPI_DATA)) {
-		Serial.println("Error: Failed to initialise connection to microSD card");
-		while(true) { delay(1); } // Pseudo-halt, but uses delay() to ensure we keep passing back control to allow easy re-programming
-	}
-}
-
-void store_reading(uint32_t id, TinyGPSLocation location) {
-	File handle;
-}

iot/main/storage.cpp

@@ -0,0 +1,33 @@
+#include <Arduino.h>
+#include <SD.h>
+
+#include "settings.h"
+
+void store_init() {
+	// NOTE: If this doesn't work, then we need to use pinMode() & specify the data pin here instead.
+	if(!SD.begin(PIN_SD_SPI_CHIP_SELECT)) {
+		Serial.println(F("Error: Failed to initialise connection to microSD card"));
+		while(true) { delay(1); } // Pseudo-halt, but uses delay() to ensure we keep passing back control to allow easy re-programming
+	}
+}
+
+void store_reading(uint32_t id, TinyGPSLocation location) {
+	// Open the file to  write the data to. If it doesn't exist it will be created.
+	// Unlike elsewhere, FILE_WRITE opens the file with the cursor starting at the end, so it's basically actually equivalent to FILE_APPEND that we use in other environments. Confusing, I know.
+	File handle = SD.open(SD_FILENAME, FILE_WRITE);
+	
+	handle.print(id);
+	handle.print("\t");
+	
+	handle.print(location.longitude());
+	handle.print("\t");
+	
+	handle.print(location.latitude());
+	handle.println();
+	
+	handle.close();
+}
+
+void store_close() {
+	SD.end();
+}