Added comments

src/modules/ESP8266.cpp

@@ -1,20 +1,26 @@
 #include "ESP8266.h"
 
 ESP8266::ESP8266(Module* module) {
-  portTcp = 80; // Default HTTP port (TCP application)
+  portTcp = 80;     // Default HTTP port (TCP application)
-  portUdp = 53; // Default DNS port (UDP application)
+  portUdp = 53;     // Default DNS port (UDP application)
   portMqtt = 1883;
   _mod = module;
 }
 
 uint8_t ESP8266::begin(long speed) {
+  // set module properties
   _mod->AtLineFeed = "\r\n";
   _mod->baudrate = speed;
   _mod->init(USE_UART, INT_NONE);
+  
+  // empty UART buffer (garbage data)
   _mod->ATemptyBuffer();
+  
+  // test AT setup
   if(!_mod->ATsendCommand("AT")) {
     return(ERR_AT_FAILED);
   }
+  
   return(ERR_NONE);
 }
 
@@ -27,7 +33,7 @@ uint8_t ESP8266::reset() {
   // wait for the module to start
   delay(2000);
   
-  // test AT
+  // test AT setup
   uint32_t start = millis();
   while (millis() - start < 3000) {
     if(!_mod->ATsendCommand("AT")) {
@@ -207,8 +213,8 @@ uint8_t ESP8266::MqttConnect(String host, String clientId, String username, Stri
   packet[5] = 'Q';
   packet[6] = 'T';
   packet[7] = 'T';
-  packet[8] = 0x04;        //protocol level
+  packet[8] = 0x04;         //protocol level
-  packet[9] = 0b11000010;  //flags: user name + password + clean session
+  packet[9] = 0b11000010;   //flags: user name + password + clean session
   packet[10] = 0x00;        //keep-alive interval MSB
   packet[11] = 0x3C;        //keep-alive interval LSB
   
@@ -230,14 +236,6 @@ uint8_t ESP8266::MqttConnect(String host, String clientId, String username, Stri
     packet[i + 18 + clientId.length() + username.length()] = (uint8_t)password.charAt(i);
   }
   
-  /*for(uint8_t i = 0; i < len + 2; i++) {
-    Serial.print(i);
-    Serial.print('\t');
-    Serial.write(packet[i]);
-    Serial.print("\t0x");
-    Serial.println(packet[i], HEX);
-  }*/
-  
   // create TCP connection
   uint8_t state = openTransportConnection(_MqttHost.c_str(), "TCP", portMqtt, 7200);
   if(state != ERR_NONE) {
@@ -251,18 +249,8 @@ uint8_t ESP8266::MqttConnect(String host, String clientId, String username, Stri
   }
   
   // read the response
-  /*uint8_t response[] = {0, 0, 0, 0, 0};
-  receive(response);*/
   String raw = receive();
   
-  /*for(uint8_t i = 0; i < raw.length(); i++) {
-    Serial.print(i);
-    Serial.print('\t');
-    Serial.write(raw.charAt(i));
-    Serial.print("\t0x");
-    Serial.println(raw.charAt(i), HEX);
-  }*/
-  
   // parse the response
   int32_t numBytesIndex = raw.indexOf(":");
   if(numBytesIndex == -1) {
@@ -274,13 +262,6 @@ uint8_t ESP8266::MqttConnect(String host, String clientId, String username, Stri
     response[i] = raw.charAt(i + numBytesIndex + 1);
   }
   
-  /*for(uint8_t i = 0; i < 4; i++) {
-    Serial.print(i);
-    Serial.print('\t');
-    Serial.write(response[i]);
-    Serial.print("\t0x");
-    Serial.println(response[i], HEX);
-  }*/
   if(response[3] != 0x00) {
     return(ERR_MQTT_CONNECTION_REFUSED);
   }
@@ -307,14 +288,6 @@ uint8_t ESP8266::MqttPublish(String topic, String message) {
     packet[i + 4 + topic.length()] = (uint8_t)message.charAt(i);
   }
   
-  /*for(uint8_t i = 0; i < len + 2; i++) {
-    Serial.print(i);
-    Serial.print('\t');
-    Serial.write(packet[i]);
-    Serial.print("\t0x");
-    Serial.println(packet[i], HEX);
-  }*/
-  
   // send MQTT packet
   uint8_t state = send(packet, len + 2);
   if(state != ERR_NONE) {
@@ -393,9 +366,6 @@ uint32_t ESP8266::receive(uint8_t* data, uint32_t timeout) {
   while(millis() - start < timeout) {
     while(_mod->ModuleSerial->available() > 0) {
       uint8_t b = _mod->ModuleSerial->read();
-      /*Serial.write(b);
-      Serial.print("\t0x");
-      Serial.println(b, HEX);*/
       #ifdef DEBUG
         Serial.print(b);
       #endif

src/modules/ESP8266.h

@@ -22,6 +22,7 @@ class ESP8266 {
   public:
     ESP8266(Module* module);
     
+    // Port numbers
     uint16_t portTcp, portUdp, portMqtt;
     
     // Basic methods

src/modules/HC05.cpp

@@ -5,6 +5,7 @@ HC05::HC05(Module* module) {
 }
 
 void HC05::begin(long speed) {
+  // set module properties
   _mod->baudrate = speed;
   _mod->init(USE_UART, INT_NONE);
 }

src/modules/RF69.cpp

@@ -5,9 +5,10 @@ RF69::RF69(Module* module) {
 }
 
 uint8_t RF69::begin() {
-  //_mod->init(USE_SPI, INT_BOTH);
+  // set module properties
   _mod->init(USE_SPI, INT_0);
   
+  // try to find the RF69 chip
   uint8_t i = 0;
   bool flagFound = false;
   while((i < 10) && !flagFound) {
@@ -49,39 +50,48 @@ uint8_t RF69::begin() {
 uint8_t RF69::transmit(Packet& pack) {
   char buffer[256];
   
+  // copy packet source and destination addresses into buffer
   for(uint8_t i = 0; i < 8; i++) {
     buffer[i] = pack.source[i];
     buffer[i+8] = pack.destination[i];
   }
   
+  // copy packet data into buffer
   for(uint8_t i = 0; i < pack.length; i++) {
     buffer[i+16] = pack.data[i];
   }
   
-  //_mod->SPIsetRegValue(RF69_REG_PACKET_CONFIG_2, RF69_RESTART_RX, 2, 2);
+  // set mode to standby
-  
   setMode(RF69_STANDBY);
   
+  // set DIO pin mapping
   _mod->SPIsetRegValue(RF69_REG_DIO_MAPPING_1, RF69_DIO0_PACK_PACKET_SENT, 7, 6);
+  
+  // clear interrupt flags
   clearIRQFlags();
   
+  // check overall packet length
   if(pack.length > 256) {
     return(ERR_PACKET_TOO_LONG);
   }
   
+  // write packet to FIFO
   _mod->SPIwriteRegister(RF69_REG_FIFO, pack.length);
   _mod->SPIwriteRegisterBurstStr(RF69_REG_FIFO, buffer, pack.length);
   
+  // set mode to transmit
   setMode(RF69_TX);
   _mod->SPIsetRegValue(RF69_REG_TEST_PA1, RF69_PA1_20_DBM);
   _mod->SPIsetRegValue(RF69_REG_TEST_PA2, RF69_PA2_20_DBM);
   
+  // wait for transmission end
   while(!_mod->getInt0State()) {
     #ifdef DEBUG
       Serial.print('.');
     #endif
   }
   
+  // clear interrupt flags
   clearIRQFlags();
   
   return(ERR_NONE);
@@ -90,18 +100,22 @@ uint8_t RF69::transmit(Packet& pack) {
 uint8_t RF69::receive(Packet& pack) {
   char buffer[256];
   
+  // set mode to standby
   setMode(RF69_STANDBY);
   
-  //_mod->SPIsetRegValue(RF69_REG_PACKET_CONFIG_2, RF69_RESTART_RX, 2, 2);
+  // set DIO pin mapping
-  
   //_mod->SPIsetRegValue(RF69_REG_DIO_MAPPING_1, RF69_DIO0_PACK_PAYLOAD_READY | RF69_DIO1_PACK_TIMEOUT, 7, 4);
   _mod->SPIsetRegValue(RF69_REG_DIO_MAPPING_1, RF69_DIO0_PACK_PAYLOAD_READY, 7, 6);
+  
+  // clear interrupt flags
   clearIRQFlags();
   
+  // set mode to receive
   setMode(RF69_RX);
   _mod->SPIsetRegValue(RF69_REG_TEST_PA1, RF69_PA1_NORMAL);
   _mod->SPIsetRegValue(RF69_REG_TEST_PA2, RF69_PA2_NORMAL);
   
+  // wait for packet reception or timeout
   /*while(!_mod->getInt0State()) {
     if(_mod->getInt1State()) {
       clearIRQFlags();
@@ -116,17 +130,20 @@ uint8_t RF69::receive(Packet& pack) {
     }
   }
   
+  // read packet from FIFO
   pack.length = _mod->SPIreadRegister(RF69_REG_FIFO);
-  
   _mod->SPIreadRegisterBurstStr(RF69_REG_FIFO, pack.length, buffer);
   
+  // clear interrupt flags
   clearIRQFlags();
   
+  // get packet source and destination addresses from buffer
   for(uint8_t i = 0; i < 8; i++) {
     pack.source[i] = buffer[i];
     pack.destination[i] = buffer[i+8];
   }
   
+  // get packet source and destination addresses from buffer
   for(uint8_t i = 16; i < pack.length; i++) {
     pack.data[i-16] = buffer[i];
   }

src/modules/SX1272.cpp

@@ -5,10 +5,12 @@ SX1272::SX1272(Module* module) {
 }
 
 uint8_t SX1272::begin(Bandwidth bw, SpreadingFactor sf, CodingRate cr, uint16_t addrEeprom) {
+  // copy LoRa modem settings
   _bw = bw;
   _sf = sf;
   _cr = cr;
   
+  // ESP32-only: initialize  EEPROM
   #ifdef ESP32
     if(!EEPROM.begin(9)) {
       #ifdef DEBUG
@@ -18,8 +20,10 @@ uint8_t SX1272::begin(Bandwidth bw, SpreadingFactor sf, CodingRate cr, uint16_t
     }
   #endif
   
+  // copy EEPROM start address
   _addrEeprom = addrEeprom;
   
+  // check if the node has address
   bool hasAddress = false;
   for(uint16_t i = 0; i < 8; i++) {
     if(EEPROM.read(_addrEeprom + i) != 255) {
@@ -28,6 +32,7 @@ uint8_t SX1272::begin(Bandwidth bw, SpreadingFactor sf, CodingRate cr, uint16_t
     }
   }
   
+  // generate new address
   if(!hasAddress) {
     randomSeed(analogRead(5));
     generateLoRaAdress();
@@ -48,8 +53,10 @@ uint8_t SX1272::begin(Bandwidth bw, SpreadingFactor sf, CodingRate cr, uint16_t
     #endif
   }
   
+  // set module properties
   _mod->init(USE_SPI, INT_BOTH);
   
+  // try to find the SX1272 chip
   uint8_t i = 0;
   bool flagFound = false;
   while((i < 10) && !flagFound) {
@@ -85,38 +92,49 @@ uint8_t SX1272::begin(Bandwidth bw, SpreadingFactor sf, CodingRate cr, uint16_t
     }
   #endif
   
+  // configure LoRa modem
   return(config(_bw, _sf, _cr));
 }
 
 uint8_t SX1272::transmit(Packet& pack) {
   char buffer[256];
   
+  // copy packet source and destination addresses into buffer
   for(uint8_t i = 0; i < 8; i++) {
     buffer[i] = pack.source[i];
     buffer[i+8] = pack.destination[i];
   }
   
+  // copy packet data into buffer
   for(uint8_t i = 0; i < pack.length; i++) {
     buffer[i+16] = pack.data[i];
   }
   
+  // set mode to standby
   setMode(SX1272_STANDBY);
   
+  // set DIO pin mapping
   _mod->SPIsetRegValue(SX1272_REG_DIO_MAPPING_1, SX1272_DIO0_TX_DONE, 7, 6);
+  
+  // clear interrupt flags
   clearIRQFlags();
   
+  // check overall packet length
   if(pack.length > 256) {
     return(ERR_PACKET_TOO_LONG);
   }
   
+  // write packet to FIFO
   _mod->SPIsetRegValue(SX1272_REG_PAYLOAD_LENGTH, pack.length);
   _mod->SPIsetRegValue(SX1272_REG_FIFO_TX_BASE_ADDR, SX1272_FIFO_TX_BASE_ADDR_MAX);
   _mod->SPIsetRegValue(SX1272_REG_FIFO_ADDR_PTR, SX1272_FIFO_TX_BASE_ADDR_MAX);
-  
   _mod->SPIwriteRegisterBurstStr(SX1272_REG_FIFO, buffer, pack.length);
   
+  
+  // set mode to transmit
   setMode(SX1272_TX);
   
+  // wait for transmission end
   unsigned long start = millis();
   while(!_mod->getInt0State()) {
     #ifdef DEBUG
@@ -124,6 +142,7 @@ uint8_t SX1272::transmit(Packet& pack) {
     #endif
   }
   
+  // clear interrupt flags
   clearIRQFlags();
   
   return(ERR_NONE);
@@ -133,16 +152,23 @@ uint8_t SX1272::receive(Packet& pack) {
   char buffer[256];
   uint32_t startTime = millis();
   
+  // set mode to standby
   setMode(SX1272_STANDBY);
   
+  // set DIO pin mapping
   _mod->SPIsetRegValue(SX1272_REG_DIO_MAPPING_1, SX1272_DIO0_RX_DONE | SX1272_DIO1_RX_TIMEOUT, 7, 4);
+  
+  // clear interrupt flags
   clearIRQFlags();
   
+  // set FIFO address pointers
   _mod->SPIsetRegValue(SX1272_REG_FIFO_RX_BASE_ADDR, SX1272_FIFO_RX_BASE_ADDR_MAX);
   _mod->SPIsetRegValue(SX1272_REG_FIFO_ADDR_PTR, SX1272_FIFO_RX_BASE_ADDR_MAX);
   
+  // set mode to receive
   setMode(SX1272_RXSINGLE);
   
+  // wait for packet reception or timeout
   while(!_mod->getInt0State()) {
     if(_mod->getInt1State()) {
       clearIRQFlags();
@@ -150,31 +176,40 @@ uint8_t SX1272::receive(Packet& pack) {
     }
   }
   
+  // check received packet CRC
   if(_mod->SPIgetRegValue(SX1272_REG_IRQ_FLAGS, 5, 5) == SX1272_CLEAR_IRQ_FLAG_PAYLOAD_CRC_ERROR) {
     return(ERR_CRC_MISMATCH);
   }
   
+  // get header type
   uint8_t headerMode = _mod->SPIgetRegValue(SX1272_REG_MODEM_CONFIG_1, 0, 0);
   if(headerMode == SX1272_HEADER_EXPL_MODE) {
     pack.length = _mod->SPIgetRegValue(SX1272_REG_RX_NB_BYTES);
   }
   
+  // read packet from FIFO
   _mod->SPIreadRegisterBurstStr(SX1272_REG_FIFO, pack.length, buffer);
   
+  // clear interrupt flags
   clearIRQFlags();
   
+  // get packet source and destination addresses from buffer
   for(uint8_t i = 0; i < 8; i++) {
     pack.source[i] = buffer[i];
     pack.destination[i] = buffer[i+8];
   }
   
+  // get packet source and destination addresses from buffer
   for(uint8_t i = 16; i < pack.length; i++) {
     pack.data[i-16] = buffer[i];
   }
   pack.data[pack.length-16] = 0;
   
+  // measure overall datarate
   uint32_t elapsedTime = millis() - startTime;
   dataRate = (pack.length*8.0)/((float)elapsedTime/1000.0);
+  
+  // get packet RSSI
   lastPacketRSSI = getLastPacketRSSI();
   
   return(ERR_NONE);

src/modules/SX1278.cpp

@@ -5,10 +5,12 @@ SX1278::SX1278(Module* module) {
 }
 
 uint8_t SX1278::begin(Bandwidth bw, SpreadingFactor sf, CodingRate cr, uint16_t addrEeprom) {
+  // copy LoRa modem settings
   _bw = bw;
   _sf = sf;
   _cr = cr;
   
+  // ESP32-only: initialize  EEPROM
   #ifdef ESP32
     if(!EEPROM.begin(9)) {
       #ifdef DEBUG
@@ -18,8 +20,10 @@ uint8_t SX1278::begin(Bandwidth bw, SpreadingFactor sf, CodingRate cr, uint16_t
     }
   #endif
   
+  // copy EEPROM start address
   _addrEeprom = addrEeprom;
   
+  // check if the node has address
   bool hasAddress = false;
   for(uint16_t i = 0; i < 8; i++) {
     if(EEPROM.read(_addrEeprom + i) != 255) {
@@ -28,6 +32,7 @@ uint8_t SX1278::begin(Bandwidth bw, SpreadingFactor sf, CodingRate cr, uint16_t
     }
   }
   
+  // generate new address
   if(!hasAddress) {
     randomSeed(analogRead(5));
     generateLoRaAdress();
@@ -48,8 +53,10 @@ uint8_t SX1278::begin(Bandwidth bw, SpreadingFactor sf, CodingRate cr, uint16_t
     #endif
   }
   
+  // set module properties
   _mod->init(USE_SPI, INT_BOTH);
   
+  // try to find the SX1278 chip
   uint8_t i = 0;
   bool flagFound = false;
   while((i < 10) && !flagFound) {
@@ -85,38 +92,48 @@ uint8_t SX1278::begin(Bandwidth bw, SpreadingFactor sf, CodingRate cr, uint16_t
     }
   #endif
   
+  // configure LoRa modem
   return(config(_bw, _sf, _cr));
 }
 
 uint8_t SX1278::transmit(Packet& pack) {
   char buffer[256];
   
+  // copy packet source and destination addresses into buffer
   for(uint8_t i = 0; i < 8; i++) {
     buffer[i] = pack.source[i];
     buffer[i+8] = pack.destination[i];
   }
   
+  // copy packet data into buffer
   for(uint8_t i = 0; i < pack.length; i++) {
     buffer[i+16] = pack.data[i];
   }
   
+  // set mode to standby
   setMode(SX1278_STANDBY);
   
+  // set DIO pin mapping
   _mod->SPIsetRegValue(SX1278_REG_DIO_MAPPING_1, SX1278_DIO0_TX_DONE, 7, 6);
+  
+  // clear interrupt flags
   clearIRQFlags();
   
+  // check overall packet length
   if(pack.length > 256) {
     return(ERR_PACKET_TOO_LONG);
   }
   
+  // write packet to FIFO
   _mod->SPIsetRegValue(SX1278_REG_PAYLOAD_LENGTH, pack.length);
   _mod->SPIsetRegValue(SX1278_REG_FIFO_TX_BASE_ADDR, SX1278_FIFO_TX_BASE_ADDR_MAX);
   _mod->SPIsetRegValue(SX1278_REG_FIFO_ADDR_PTR, SX1278_FIFO_TX_BASE_ADDR_MAX);
-  
   _mod->SPIwriteRegisterBurstStr(SX1278_REG_FIFO, buffer, pack.length);
   
+  // set mode to transmit
   setMode(SX1278_TX);
   
+  // wait for transmission end
   unsigned long start = millis();
   while(!_mod->getInt0State()) {
     #ifdef DEBUG
@@ -124,6 +141,7 @@ uint8_t SX1278::transmit(Packet& pack) {
     #endif
   }
   
+  // clear interrupt flags
   clearIRQFlags();
   
   return(ERR_NONE);
@@ -133,16 +151,23 @@ uint8_t SX1278::receive(Packet& pack) {
   char buffer[256];
   uint32_t startTime = millis();
   
+  // set mode to standby
   setMode(SX1278_STANDBY);
   
+  // set DIO pin mapping
   _mod->SPIsetRegValue(SX1278_REG_DIO_MAPPING_1, SX1278_DIO0_RX_DONE | SX1278_DIO1_RX_TIMEOUT, 7, 4);
+  
+  // clear interrupt flags
   clearIRQFlags();
   
+  // set FIFO address pointers
   _mod->SPIsetRegValue(SX1278_REG_FIFO_RX_BASE_ADDR, SX1278_FIFO_RX_BASE_ADDR_MAX);
   _mod->SPIsetRegValue(SX1278_REG_FIFO_ADDR_PTR, SX1278_FIFO_RX_BASE_ADDR_MAX);
   
+  // set mode to receive
   setMode(SX1278_RXSINGLE);
   
+  // wait for packet reception or timeout
   while(!_mod->getInt0State()) {
     if(_mod->getInt1State()) {
       clearIRQFlags();
@@ -150,31 +175,40 @@ uint8_t SX1278::receive(Packet& pack) {
     }
   }
   
+  // check received packet CRC
   if(_mod->SPIgetRegValue(SX1278_REG_IRQ_FLAGS, 5, 5) == SX1278_CLEAR_IRQ_FLAG_PAYLOAD_CRC_ERROR) {
     return(ERR_CRC_MISMATCH);
   }
   
+  // get header type
   uint8_t headerMode = _mod->SPIgetRegValue(SX1278_REG_MODEM_CONFIG_1, 0, 0);
   if(headerMode == SX1278_HEADER_EXPL_MODE) {
     pack.length = _mod->SPIgetRegValue(SX1278_REG_RX_NB_BYTES);
   }
   
+  // read packet from FIFO
   _mod->SPIreadRegisterBurstStr(SX1278_REG_FIFO, pack.length, buffer);
   
+  // clear interrupt flags
   clearIRQFlags();
   
+  // get packet source and destination addresses from buffer
   for(uint8_t i = 0; i < 8; i++) {
     pack.source[i] = buffer[i];
     pack.destination[i] = buffer[i+8];
   }
   
+  // get packet source and destination addresses from buffer
   for(uint8_t i = 16; i < pack.length; i++) {
     pack.data[i-16] = buffer[i];
   }
   pack.data[pack.length-16] = 0;
   
+  // measure overall datarate
   uint32_t elapsedTime = millis() - startTime;
   dataRate = (pack.length*8.0)/((float)elapsedTime/1000.0);
+  
+  // get packet RSSI
   lastPacketRSSI = getLastPacketRSSI();
   
   return(ERR_NONE);

src/modules/XBee.cpp

@@ -10,20 +10,23 @@ XBee::XBee(Module* module) {
 }
 
 uint8_t XBee::begin(long speed) {
+  // set Arduino pins
   pinMode(A4, OUTPUT);
   pinMode(A5, OUTPUT);
-  //pinMode(3, INPUT);
   pinMode(3, OUTPUT);
   digitalWrite(A4, LOW);
   digitalWrite(A5, LOW);
   digitalWrite(3, HIGH);
   
+  // set module properties
   _mod->AtLineFeed = "\r";
-  
   _mod->baudrate = speed;
   _mod->init(USE_UART, INT_NONE);
+  
+  // empty UART buffer (garbage data)
   _mod->ATemptyBuffer();
   
+  // enter command mode
   #ifdef DEBUG
     Serial.println("Entering command mode ...");
   #endif
@@ -31,6 +34,7 @@ uint8_t XBee::begin(long speed) {
     return(ERR_CMD_MODE_FAILED);
   }
   
+  // test AT setup
   #ifdef DEBUG
     Serial.println("Sending test command ...");
   #endif
@@ -38,6 +42,7 @@ uint8_t XBee::begin(long speed) {
     return(ERR_AT_FAILED);
   }
   
+  // exit command mode
   #ifdef DEBUG
     Serial.println("Exiting command mode ...");
   #endif
@@ -51,6 +56,7 @@ uint8_t XBee::begin(long speed) {
 }
 
 uint8_t XBee::setDestinationAddress(const char destinationAddressHigh[], const char destinationAddressLow[]) {
+  // enter command mode
   #ifdef DEBUG
     Serial.println("Entering command mode ...");
   #endif
@@ -58,6 +64,7 @@ uint8_t XBee::setDestinationAddress(const char destinationAddressHigh[], const c
     return(ERR_CMD_MODE_FAILED);
   }
   
+  // set higher address bytes
   #ifdef DEBUG
     Serial.println("Setting address (high) ...");
   #endif
@@ -67,6 +74,7 @@ uint8_t XBee::setDestinationAddress(const char destinationAddressHigh[], const c
     return(ERR_AT_FAILED);
   }
   
+  // set lower address bytes
   #ifdef DEBUG
     Serial.println("Setting address (low) ...");
   #endif
@@ -76,6 +84,7 @@ uint8_t XBee::setDestinationAddress(const char destinationAddressHigh[], const c
     return(ERR_AT_FAILED);
   }
   
+  // exit command mode
   #ifdef DEBUG
     Serial.println("Exiting command mode ...");
   #endif
@@ -87,6 +96,7 @@ uint8_t XBee::setDestinationAddress(const char destinationAddressHigh[], const c
 }
 
 uint8_t XBee::setPanId(const char panId[]) {
+  // enter command mode
   #ifdef DEBUG
     Serial.println("Entering command mode ...");
   #endif
@@ -94,6 +104,7 @@ uint8_t XBee::setPanId(const char panId[]) {
     return(ERR_CMD_MODE_FAILED);
   }
   
+  // set PAN ID
   #ifdef DEBUG
     Serial.println("Setting PAN ID ...");
   #endif
@@ -103,6 +114,7 @@ uint8_t XBee::setPanId(const char panId[]) {
     return(ERR_AT_FAILED);
   }
   
+  // exit command mode
   #ifdef DEBUG
     Serial.println("Exiting command mode ...");
   #endif