docs: Add comments

Aiolos_Drone.ino

@@ -1,5 +1,7 @@
- #include "RYLR896.h"
+// Import LoRa Module Library
+#include "RYLR896.h"
 
+// Drone ID, for future use when using with multiple drones
 #define DRONE_ID 1
 
 int MQ2 = A0;
@@ -11,14 +13,18 @@ int MQ8 = A5;
 int MQ9 = A6;
 int MQ135 = A7;
 
+// Define Serial interfaces for GPS and LoRa (easier configuration)
 #define GPS_SERIAL Serial1
 #define LORA_SERIAL Serial3
 
+// Create global LoRa library object
 RYLR896* lora;
 
 void setup() {
+  // Initialize Serial0 for debug messages
   Serial.begin(115200);
   Serial.println("Starting up...");
+  // Set sensor pin modes
   pinMode(MQ2, INPUT);
   pinMode(MQ4, INPUT);
   pinMode(MQ5, INPUT);
@@ -28,16 +34,24 @@ void setup() {
   pinMode(MQ9, INPUT);
   pinMode(MQ135, INPUT);
   Serial.println("Initializing communications...");
+  // Initialize LoRa's serial interface outside the library because of
+  // weird HardwareSerial.h behavior when called within another library.
   Serial3.begin(115200);
+  // Initialize LoRa Library
   lora = new RYLR896(&LORA_SERIAL, 115200);
+  // Set RF Parameters for close range message transmission 
+  // (see: page 2, http://reyax.com/wp-content/uploads/2018/01/REYAX-Lora-AT-COMMAND-GUIDE_EN.pdf)
   lora->SetRFParamsLessThan3KM();
+  // Set AES encryption passcode
   lora->SetAESPassword("FABC0002EEDCAA90FABC0002EEDCAA90");
   Serial.println("Initializing GPS...");
+  // Initialize GPS' serial interface
   GPS_SERIAL.begin(9600);
   Serial.println("Setup completed!");
 }
 
 void loop() {
+  // Read sensor values
   float GAS_MQ2 = analogRead(MQ2);
   float GAS_MQ4 = analogRead(MQ4);
   float GAS_MQ5 = analogRead(MQ5);
@@ -47,29 +61,19 @@ void loop() {
   float GAS_MQ9 = analogRead(MQ9);
   float GAS_MQ135 = analogRead(MQ135);
 
+  // Once we have available GPS data
   if (GPS_SERIAL.available() > 0){
+    // Store NMEA sentence
     String gpsData = GPS_SERIAL.readStringUntil('\n');
+    // Since we are only keeping GPRMC NMEA sentences, only enter
+    // if we are on that sentence (see http://aprs.gids.nl/nmea/#rmc)
     if (gpsData.startsWith("$GPRMC")){
+      // Construct message to send over LoRa
       String data = String(DRONE_ID) + "|" + gpsData + "|" + "MQ2=" + String(GAS_MQ2) + "|" + "MQ4=" + String(GAS_MQ4) + "|" + "MQ5=" + String(GAS_MQ5) + "|" + "MQ6=" + String(GAS_MQ6) + "|" + "MQ7=" + String(GAS_MQ7) + "|" + "MQ8=" + String(GAS_MQ8) + "|" + "MQ9=" + String(GAS_MQ9) + "|" + "MQ135=" + String(GAS_MQ135);
-      // Serial.print("MQ2: ");
-      // Serial.println(GAS_MQ2);
-      // Serial.print("MQ4: ");
-      // Serial.println(GAS_MQ4);
-      // Serial.print("MQ5: ");
-      // Serial.println(GAS_MQ5);
-      // Serial.print("MQ6: ");
-      // Serial.println(GAS_MQ6);
-      // Serial.print("MQ7: ");
-      // Serial.println(GAS_MQ7);
-      // Serial.print("MQ8: ");
-      // Serial.println(GAS_MQ8);
-      // Serial.print("MQ9: ");
-      // Serial.println(GAS_MQ9);
-      // Serial.print("MQ135: ");
-      // Serial.println(GAS_MQ135);
-      // Serial.println("\n");
+      // Print a debug message on Serial0 with the data we are about to send
       Serial.println(data);
+      // Transmit message over LoRa
       lora->Send(data);
     }
   }
-}
+}