[LoRaWAN] Add datarate into event structure (#885)

* [LoRaWAN] Move TX power logic to function

* Update keywords

* [LoRaWAN] Add datarate into event structure

examples/LoRaWAN/LoRaWAN_End_Device_Reference/LoRaWAN_End_Device_Reference.ino

@@ -214,6 +214,8 @@ void loop() {
     Serial.println(event.confirmed);
     Serial.print(F("[LoRaWAN] Confirming:\t"));
     Serial.println(event.confirming);
+    Serial.print(F("[LoRaWAN] Datarate:\t"));
+    Serial.print(event.datarate);
     Serial.print(F("[LoRaWAN] Frequency:\t"));
     Serial.print(event.freq, 3);
     Serial.println(F(" MHz"));

src/protocols/LoRaWAN/LoRaWAN.cpp

@@ -904,6 +904,7 @@ int16_t LoRaWANNode::uplink(uint8_t* data, size_t len, uint8_t port, bool isConf
     event->dir = RADIOLIB_LORAWAN_CHANNEL_DIR_UPLINK;
     event->confirmed = isConfirmed;
     event->confirming = isConfirmingDown;
+    event->datarate = this->dataRates[RADIOLIB_LORAWAN_CHANNEL_DIR_UPLINK];
     event->freq = currentChannels[event->dir].freq;
     event->power = this->txPwrCur;
     event->fcnt = this->fcntUp;
@@ -1262,6 +1263,7 @@ int16_t LoRaWANNode::downlink(uint8_t* data, size_t* len, LoRaWANEvent_t* event)
     event->dir = RADIOLIB_LORAWAN_CHANNEL_DIR_DOWNLINK;
     event->confirmed = isConfirmedDown;
     event->confirming = isConfirmingUp;
+    event->datarate = this->dataRates[RADIOLIB_LORAWAN_CHANNEL_DIR_DOWNLINK];
     event->freq = currentChannels[event->dir].freq;
     event->power = this->txPwrCur;
     event->fcnt = isAppDownlink ? this->aFcntDown : this->nFcntDown;

src/protocols/LoRaWAN/LoRaWAN.h

@@ -325,6 +325,9 @@ struct LoRaWANEvent_t {
   /*! \brief Whether the event is confirming a previous request
   (e.g., server downlink reply to confirmed uplink sent by user application)*/
   bool confirming;
+
+  /*! \brief Datarate */
+  uint8_t datarate;
   
   /*! \brief Frequency in MHz */
   float freq;