LoRaWAN.h

#if !defined(_RADIOLIB_LORAWAN_H) && !defined(RADIOLIB_EXCLUDE_LORAWAN)
#define _RADIOLIB_LORAWAN_H
 
#include "../../TypeDef.h"
#include "../PhysicalLayer/PhysicalLayer.h"
#include "../../utils/Cryptography.h"
 
// version of NVM table layout (NOT the LoRaWAN version)
#define RADIOLIB_PERSISTENT_PARAM_LORAWAN_TABLE_VERSION         (0x01)
 
// preamble format
#define RADIOLIB_LORAWAN_LORA_SYNC_WORD                         (0x34)
#define RADIOLIB_LORAWAN_LORA_PREAMBLE_LEN                      (8)
#define RADIOLIB_LORAWAN_GFSK_SYNC_WORD                         (0xC194C1)
#define RADIOLIB_LORAWAN_GFSK_PREAMBLE_LEN                      (5)
 
// MAC header field encoding                                                    MSB   LSB   DESCRIPTION
#define RADIOLIB_LORAWAN_MHDR_MTYPE_JOIN_REQUEST                (0x00 << 5) //  7     5     message type: join request
#define RADIOLIB_LORAWAN_MHDR_MTYPE_JOIN_ACCEPT                 (0x01 << 5) //  7     5                   join accept
#define RADIOLIB_LORAWAN_MHDR_MTYPE_UNCONF_DATA_UP              (0x02 << 5) //  7     5                   unconfirmed data up
#define RADIOLIB_LORAWAN_MHDR_MTYPE_UNCONF_DATA_DOWN            (0x03 << 5) //  7     5                   unconfirmed data down
#define RADIOLIB_LORAWAN_MHDR_MTYPE_CONF_DATA_UP                (0x04 << 5) //  7     5                   confirmed data up
#define RADIOLIB_LORAWAN_MHDR_MTYPE_CONF_DATA_DOWN              (0x05 << 5) //  7     5                   confirmed data down
#define RADIOLIB_LORAWAN_MHDR_MTYPE_PROPRIETARY                 (0x07 << 5) //  7     5                   proprietary
#define RADIOLIB_LORAWAN_MHDR_MTYPE_MASK                        (0x07 << 5) //  7     5                   bitmask of all possible options
#define RADIOLIB_LORAWAN_MHDR_MAJOR_R1                          (0x00 << 0) //  1     0     major version: LoRaWAN R1
 
// frame control field encoding
#define RADIOLIB_LORAWAN_FCTRL_ADR_ENABLED                      (0x01 << 7) //  7     7     adaptive data rate: enabled
#define RADIOLIB_LORAWAN_FCTRL_ADR_DISABLED                     (0x00 << 7) //  7     7                         disabled
#define RADIOLIB_LORAWAN_FCTRL_ADR_ACK_REQ                      (0x01 << 6) //  6     6     adaptive data rate ACK request
#define RADIOLIB_LORAWAN_FCTRL_ACK                              (0x01 << 5) //  5     5     confirmed message acknowledge
#define RADIOLIB_LORAWAN_FCTRL_FRAME_PENDING                    (0x01 << 4) //  4     4     downlink frame is pending
 
// port field
#define RADIOLIB_LORAWAN_FPORT_MAC_COMMAND                      (0x00 << 0) //  7     0     payload contains MAC commands only
#define RADIOLIB_LORAWAN_FPORT_RESERVED                         (0xE0 << 0) //  7     0     reserved port values
 
// MAC commands - only those sent from end-device to gateway
#define RADIOLIB_LORAWAN_LINK_CHECK_REQ                         (0x02 << 0) //  7     0     MAC command: request to check connectivity to network
#define RADIOLIB_LORAWAN_LINK_ADR_ANS                           (0x03 << 0) //  7     0                  answer to ADR change
#define RADIOLIB_LORAWAN_DUTY_CYCLE_ANS                         (0x04 << 0) //  7     0                  answer to duty cycle change
#define RADIOLIB_LORAWAN_RX_PARAM_SETUP_ANS                     (0x05 << 0) //  7     0                  answer to reception slot setup request
#define RADIOLIB_LORAWAN_DEV_STATUS_ANS                         (0x06 << 0) //  7     0                  device status information
#define RADIOLIB_LORAWAN_NEW_CHANNEL_ANS                        (0x07 << 0) //  7     0                  acknowledges change of a radio channel
#define RADIOLIB_LORAWAN_RX_TIMING_SETUP_ANS                    (0x08 << 0) //  7     0                  acknowledges change of a reception slots timing
 
#define RADIOLIB_LORAWAN_NOPTS_LEN                              (8)
 
// data rate encoding
#define RADIOLIB_LORAWAN_DATA_RATE_FSK_50_K                     (0x01 << 7) //  7     7     FSK @ 50 kbps
#define RADIOLIB_LORAWAN_DATA_RATE_SF_12                        (0x06 << 4) //  6     4     LoRa spreading factor: SF12
#define RADIOLIB_LORAWAN_DATA_RATE_SF_11                        (0x05 << 4) //  6     4                             SF11
#define RADIOLIB_LORAWAN_DATA_RATE_SF_10                        (0x04 << 4) //  6     4                             SF10
#define RADIOLIB_LORAWAN_DATA_RATE_SF_9                         (0x03 << 4) //  6     4                             SF9
#define RADIOLIB_LORAWAN_DATA_RATE_SF_8                         (0x02 << 4) //  6     4                             SF8
#define RADIOLIB_LORAWAN_DATA_RATE_SF_7                         (0x01 << 4) //  6     4                             SF7
#define RADIOLIB_LORAWAN_DATA_RATE_BW_500_KHZ                   (0x00 << 2) //  3     2     LoRa bandwidth: 500 kHz
#define RADIOLIB_LORAWAN_DATA_RATE_BW_250_KHZ                   (0x01 << 2) //  3     2                     250 kHz
#define RADIOLIB_LORAWAN_DATA_RATE_BW_125_KHZ                   (0x02 << 2) //  3     2                     125 kHz
#define RADIOLIB_LORAWAN_DATA_RATE_BW_RESERVED                  (0x03 << 2) //  3     2                     reserved value
#define RADIOLIB_LORAWAN_DATA_RATE_CR_4_5                       (0x00 << 0) //  1     0     LoRa coding rate: 4/5
#define RADIOLIB_LORAWAN_DATA_RATE_CR_4_6                       (0x01 << 0) //  1     0                       4/6
#define RADIOLIB_LORAWAN_DATA_RATE_CR_4_7                       (0x02 << 0) //  1     0                       4/7
#define RADIOLIB_LORAWAN_DATA_RATE_CR_4_8                       (0x03 << 0) //  1     0                       4/8
#define RADIOLIB_LORAWAN_DATA_RATE_UNUSED                       (0xFF << 0) //  7     0     unused data rate
 
#define RADIOLIB_LORAWAN_CHANNEL_DIR_UPLINK                     (0x00 << 0)
#define RADIOLIB_LORAWAN_CHANNEL_DIR_DOWNLINK                   (0x01 << 0)
#define RADIOLIB_LORAWAN_CHANNEL_DIR_BOTH                       (0x02 << 0)
#define RADIOLIB_LORAWAN_CHANNEL_DIR_NONE                       (0x03 << 0)
#define RADIOLIB_LORAWAN_BAND_DYNAMIC                           (0)
#define RADIOLIB_LORAWAN_BAND_FIXED                             (1)
#define RADIOLIB_LORAWAN_CHANNEL_NUM_DATARATES                  (15)
#define RADIOLIB_LORAWAN_CHANNEL_INDEX_NONE                     (0xFF >> 1) // reserve first bit for enable-flag
 
// recommended default settings
#define RADIOLIB_LORAWAN_RECEIVE_DELAY_1_MS                     (1000)
#define RADIOLIB_LORAWAN_RECEIVE_DELAY_2_MS                     ((RADIOLIB_LORAWAN_RECEIVE_DELAY_1_MS) + 1000)
#define RADIOLIB_LORAWAN_RX_WINDOW_LEN_MS                       (500)
#define RADIOLIB_LORAWAN_RX1_DR_OFFSET                          (0)
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_DELAY_1_MS                 (5000)
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_DELAY_2_MS                 (6000)
#define RADIOLIB_LORAWAN_MAX_FCNT_GAP                           (16384)
#define RADIOLIB_LORAWAN_ADR_ACK_LIMIT_EXP                      (0x06)
#define RADIOLIB_LORAWAN_ADR_ACK_DELAY_EXP                      (0x05)
#define RADIOLIB_LORAWAN_RETRANSMIT_TIMEOUT_MIN_MS              (1000)
#define RADIOLIB_LORAWAN_RETRANSMIT_TIMEOUT_MAX_MS              (3000)
#define RADIOLIB_LORAWAN_POWER_STEP_SIZE_DBM                    (-2)
 
// join request message layout
#define RADIOLIB_LORAWAN_JOIN_REQUEST_LEN                       (23)
#define RADIOLIB_LORAWAN_JOIN_REQUEST_JOIN_EUI_POS              (1)
#define RADIOLIB_LORAWAN_JOIN_REQUEST_DEV_EUI_POS               (9)
#define RADIOLIB_LORAWAN_JOIN_REQUEST_DEV_NONCE_POS             (17)
#define RADIOLIB_LORAWAN_JOIN_REQUEST_TYPE                      (0xFF)
#define RADIOLIB_LORAWAN_JOIN_REQUEST_TYPE_0                    (0x00)
#define RADIOLIB_LORAWAN_JOIN_REQUEST_TYPE_1                    (0x01)
#define RADIOLIB_LORAWAN_JOIN_REQUEST_TYPE_2                    (0x02)
 
// join accept message layout
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_MAX_LEN                    (33)
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_JOIN_NONCE_POS             (1)
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_HOME_NET_ID_POS            (4)
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_DEV_ADDR_POS               (7)
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_JOIN_EUI_POS               (4)
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_DL_SETTINGS_POS            (11)
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_RX_DELAY_POS               (12)
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_DEV_NONCE_POS              (12)
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_CFLIST_POS                 (13)
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_CFLIST_LEN                 (16)
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_CFLIST_TYPE_POS            (RADIOLIB_LORAWAN_JOIN_ACCEPT_CFLIST_POS + RADIOLIB_LORAWAN_JOIN_ACCEPT_CFLIST_LEN - 1)
 
// join accept message variables
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_R_1_0                      (0x00 << 7) //  7     7     LoRaWAN revision: 1.0
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_R_1_1                      (0x01 << 7) //  7     7                       1.1
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_F_NWK_S_INT_KEY            (0x01)
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_APP_S_KEY                  (0x02)
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_S_NWK_S_INT_KEY            (0x03)
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_NWK_S_ENC_KEY              (0x04)
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_JS_ENC_KEY                 (0x05)
#define RADIOLIB_LORAWAN_JOIN_ACCEPT_JS_INT_KEY                 (0x06)
 
// frame header layout
#define RADIOLIB_LORAWAN_FHDR_LEN_START_OFFS                    (16)
#define RADIOLIB_LORAWAN_FHDR_DEV_ADDR_POS                      (RADIOLIB_LORAWAN_FHDR_LEN_START_OFFS + 1)
#define RADIOLIB_LORAWAN_FHDR_FCTRL_POS                         (RADIOLIB_LORAWAN_FHDR_LEN_START_OFFS + 5)
#define RADIOLIB_LORAWAN_FHDR_FCNT_POS                          (RADIOLIB_LORAWAN_FHDR_LEN_START_OFFS + 6)
#define RADIOLIB_LORAWAN_FHDR_FOPTS_POS                         (RADIOLIB_LORAWAN_FHDR_LEN_START_OFFS + 8)
#define RADIOLIB_LORAWAN_FHDR_FOPTS_LEN_MASK                    (0x0F)
#define RADIOLIB_LORAWAN_FHDR_FOPTS_MAX_LEN                     (RADIOLIB_LORAWAN_FHDR_LEN_START_OFFS + 16)
#define RADIOLIB_LORAWAN_FHDR_FPORT_POS(FOPTS)                  (RADIOLIB_LORAWAN_FHDR_LEN_START_OFFS + 8 + (FOPTS))
#define RADIOLIB_LORAWAN_FRAME_PAYLOAD_POS(FOPTS)               (RADIOLIB_LORAWAN_FHDR_LEN_START_OFFS + 9 + (FOPTS))
#define RADIOLIB_LORAWAN_FRAME_LEN(PAYLOAD, FOPTS)              (16 + 13 + (PAYLOAD) + (FOPTS))
 
// payload encryption/MIC blocks common layout
#define RADIOLIB_LORAWAN_BLOCK_MAGIC_POS                        (0)
#define RADIOLIB_LORAWAN_BLOCK_CONF_FCNT_POS                    (1)
#define RADIOLIB_LORAWAN_BLOCK_DIR_POS                          (5)
#define RADIOLIB_LORAWAN_BLOCK_DEV_ADDR_POS                     (6)
#define RADIOLIB_LORAWAN_BLOCK_FCNT_POS                         (10)
 
// payload encryption block layout
#define RADIOLIB_LORAWAN_ENC_BLOCK_MAGIC                        (0x01)
#define RADIOLIB_LORAWAN_ENC_BLOCK_COUNTER_ID_POS               (4)
#define RADIOLIB_LORAWAN_ENC_BLOCK_COUNTER_POS                  (15)
 
// payload MIC blocks layout
#define RADIOLIB_LORAWAN_MIC_BLOCK_MAGIC                        (0x49)
#define RADIOLIB_LORAWAN_MIC_BLOCK_LEN_POS                      (15)
#define RADIOLIB_LORAWAN_MIC_DATA_RATE_POS                      (3)
#define RADIOLIB_LORAWAN_MIC_CH_INDEX_POS                       (4)
 
// magic word saved in persistent memory upon activation
#define RADIOLIB_LORAWAN_MAGIC                                  (0x39EA)
 
// MAC commands
#define RADIOLIB_LORAWAN_MAC_CMD_RESET                          (0x01)
#define RADIOLIB_LORAWAN_MAC_CMD_LINK_CHECK                     (0x02)
#define RADIOLIB_LORAWAN_MAC_CMD_LINK_ADR                       (0x03)
#define RADIOLIB_LORAWAN_MAC_CMD_DUTY_CYCLE                     (0x04)
#define RADIOLIB_LORAWAN_MAC_CMD_RX_PARAM_SETUP                 (0x05)
#define RADIOLIB_LORAWAN_MAC_CMD_DEV_STATUS                     (0x06)
#define RADIOLIB_LORAWAN_MAC_CMD_NEW_CHANNEL                    (0x07)
#define RADIOLIB_LORAWAN_MAC_CMD_RX_TIMING_SETUP                (0x08)
#define RADIOLIB_LORAWAN_MAC_CMD_TX_PARAM_SETUP                 (0x09)
#define RADIOLIB_LORAWAN_MAC_CMD_DL_CHANNEL                     (0x0A)
#define RADIOLIB_LORAWAN_MAC_CMD_REKEY                          (0x0B)
#define RADIOLIB_LORAWAN_MAC_CMD_ADR_PARAM_SETUP                (0x0C)
#define RADIOLIB_LORAWAN_MAC_CMD_DEVICE_TIME                    (0x0D)
#define RADIOLIB_LORAWAN_MAC_CMD_FORCE_REJOIN                   (0x0E)
#define RADIOLIB_LORAWAN_MAC_CMD_REJOIN_PARAM_SETUP             (0x0F)
#define RADIOLIB_LORAWAN_MAC_CMD_PROPRIETARY                    (0x80)
 
// unused frame counter value
#define RADIOLIB_LORAWAN_FCNT_NONE                              (0xFFFFFFFF)
 
// the length of internal MAC command queue - hopefully this is enough for most use cases
#define RADIOLIB_LORAWAN_MAC_COMMAND_QUEUE_SIZE                 (8)
 
// the maximum number of simultaneously available channels
#define RADIOLIB_LORAWAN_NUM_AVAILABLE_CHANNELS                 (16)
 
struct LoRaWANChannel_t {
  bool enabled;
 
  uint8_t idx;
 
  float freq;
 
  uint8_t drMin;
 
  uint8_t drMax;
};
 
// alias for unused channel
#define RADIOLIB_LORAWAN_CHANNEL_NONE    { .enabled = false, .idx = RADIOLIB_LORAWAN_CHANNEL_INDEX_NONE, .freq = 0, .drMin = 0, .drMax = 0 }
 
struct LoRaWANChannelSpan_t {
  uint8_t numChannels;
 
  float freqStart;
 
  float freqStep;
 
  uint8_t drMin;
 
  uint8_t drMax;
  
  uint8_t joinRequestDataRate;
};
 
// alias for unused channel span
#define RADIOLIB_LORAWAN_CHANNEL_SPAN_NONE    { .numChannels = 0, .freqStart = 0, .freqStep = 0, .drMin = 0, .drMax = 0, .joinRequestDataRate = RADIOLIB_LORAWAN_DATA_RATE_UNUSED }
 
struct LoRaWANBand_t {
  uint8_t bandType;
 
  uint8_t payloadLenMax[RADIOLIB_LORAWAN_CHANNEL_NUM_DATARATES];
 
  int8_t powerMax;
 
  int8_t powerNumSteps;
 
  LoRaWANChannel_t txFreqs[3];
 
  LoRaWANChannel_t txJoinReq[3];
  
  uint8_t numTxSpans;
 
  LoRaWANChannelSpan_t txSpans[2];
 
  LoRaWANChannelSpan_t rx1Span;
 
  uint8_t rx1DataRateBase;
 
  LoRaWANChannel_t rx2;
  
  uint8_t dataRates[RADIOLIB_LORAWAN_CHANNEL_NUM_DATARATES];
};
 
// supported bands
extern const LoRaWANBand_t EU868;
extern const LoRaWANBand_t US915;
extern const LoRaWANBand_t CN780;
extern const LoRaWANBand_t EU433;
extern const LoRaWANBand_t AU915;
extern const LoRaWANBand_t CN500;
extern const LoRaWANBand_t AS923;
extern const LoRaWANBand_t KR920;
extern const LoRaWANBand_t IN865;
 
struct LoRaWANMacCommand_t {
  uint8_t cid;
 
  uint8_t payload[5];
 
  uint8_t len;
 
  uint8_t repeat;
};
 
struct LoRaWANMacCommandQueue_t {
  uint8_t numCommands;
  uint8_t len;
  LoRaWANMacCommand_t commands[RADIOLIB_LORAWAN_MAC_COMMAND_QUEUE_SIZE];
};
 
struct LoRaWANEvent_t {
  uint8_t dir;
  
  bool confirmed;
  
  bool confirming;
  
  float freq;
  
  int16_t power;
  
  uint32_t fcnt;
  
  uint8_t port;
};
 
class LoRaWANNode {
  public:
 
    // Offset between TX and RX1 (such that RX1 has equal or lower DR)
    uint8_t rx1DrOffset;
 
    // RX2 channel properties - may be changed by MAC command
    LoRaWANChannel_t rx2;
 
    LoRaWANNode(PhysicalLayer* phy, const LoRaWANBand_t* band);
 
#if !defined(RADIOLIB_EEPROM_UNSUPPORTED)
    void wipe();
 
    int16_t restore();
#endif
 
    int16_t beginOTAA(uint64_t joinEUI, uint64_t devEUI, uint8_t* nwkKey, uint8_t* appKey, uint8_t joinDr = RADIOLIB_LORAWAN_DATA_RATE_UNUSED, bool force = false);
 
    int16_t beginABP(uint32_t addr, uint8_t* nwkSKey, uint8_t* appSKey, uint8_t* fNwkSIntKey = NULL, uint8_t* sNwkSIntKey = NULL, bool force = false);
 
    bool isJoined();
 
    int16_t saveSession();
 
    #if defined(RADIOLIB_BUILD_ARDUINO)
    int16_t uplink(String& str, uint8_t port, bool isConfirmed = false, LoRaWANEvent_t* event = NULL);
    #endif
 
    int16_t uplink(const char* str, uint8_t port, bool isConfirmed = false, LoRaWANEvent_t* event = NULL);
 
    int16_t uplink(uint8_t* data, size_t len, uint8_t port, bool isConfirmed = false, LoRaWANEvent_t* event = NULL);
 
    #if defined(RADIOLIB_BUILD_ARDUINO)
    int16_t downlink(String& str, LoRaWANEvent_t* event = NULL);
    #endif
 
    int16_t downlink(uint8_t* data, size_t* len, LoRaWANEvent_t* event = NULL);
 
    #if defined(RADIOLIB_BUILD_ARDUINO)
    int16_t sendReceive(String& strUp, uint8_t port, String& strDown, bool isConfirmed = false, LoRaWANEvent_t* eventUp = NULL, LoRaWANEvent_t* eventDown = NULL);
    #endif
 
    int16_t sendReceive(const char* strUp, uint8_t port, uint8_t* dataDown, size_t* lenDown, bool isConfirmed = false, LoRaWANEvent_t* eventUp = NULL, LoRaWANEvent_t* eventDown = NULL);
 
    int16_t sendReceive(uint8_t* dataUp, size_t lenUp, uint8_t port, uint8_t* dataDown, size_t* lenDown, bool isConfirmed = false, LoRaWANEvent_t* eventUp = NULL, LoRaWANEvent_t* eventDown = NULL);
 
    void setDeviceStatus(uint8_t battLevel);
 
    uint32_t getFcntUp();
 
    int16_t setDatarate(uint8_t drUp);
 
    void setADR(bool enable = true);
 
    int16_t selectSubband(uint8_t idx);
 
    int16_t selectSubband(uint8_t startChannel, uint8_t endChannel);
 
    void setCSMA(uint8_t backoffMax, uint8_t difsSlots, bool enableCSMA = false);
 
#if !defined(RADIOLIB_GODMODE)
  private:
#endif
    PhysicalLayer* phyLayer = NULL;
    const LoRaWANBand_t* band = NULL;
 
    LoRaWANMacCommandQueue_t commandsUp = { 
      .numCommands = 0,
      .len = 0,
      .commands = { { .cid = 0, .payload = { 0 }, .len = 0, .repeat = 0, } },
    };
    LoRaWANMacCommandQueue_t commandsDown = { 
      .numCommands = 0,
      .len = 0,
      .commands = { { .cid = 0, .payload = { 0 }, .len = 0, .repeat = 0, } },
    };
 
    // the following is either provided by the network server (OTAA)
    // or directly entered by the user (ABP)
    uint32_t devAddr = 0;
    uint8_t appSKey[RADIOLIB_AES128_KEY_SIZE] = { 0 };
    uint8_t fNwkSIntKey[RADIOLIB_AES128_KEY_SIZE] = { 0 };
    uint8_t sNwkSIntKey[RADIOLIB_AES128_KEY_SIZE] = { 0 };
    uint8_t nwkSEncKey[RADIOLIB_AES128_KEY_SIZE] = { 0 };
    uint8_t jSIntKey[RADIOLIB_AES128_KEY_SIZE] = { 0 };
    
    // device-specific parameters, persistent through sessions
    uint16_t devNonce = 0;
    uint32_t joinNonce = 0;
 
    // session-specific parameters
    uint32_t homeNetId = 0;
    uint8_t adrLimitExp = RADIOLIB_LORAWAN_ADR_ACK_LIMIT_EXP;
    uint8_t adrDelayExp = RADIOLIB_LORAWAN_ADR_ACK_DELAY_EXP;
    uint8_t nbTrans = 1;            // Number of allowed frame retransmissions
    uint8_t txPwrCur = 0;
    uint32_t fcntUp = 0;
    uint32_t aFcntDown = 0;
    uint32_t nFcntDown = 0;
    uint32_t confFcntUp = RADIOLIB_LORAWAN_FCNT_NONE;
    uint32_t confFcntDown = RADIOLIB_LORAWAN_FCNT_NONE;
    uint32_t adrFcnt = 0;
 
    // whether the current configured channel is in FSK mode
    bool FSK;
 
    // flag that shows whether the device is joined and there is an ongoing session
    bool isJoinedFlag = false;
 
    // ADR is enabled by default
    bool adrEnabled = true;
    
    // enable/disable CSMA for LoRaWAN
    bool enableCSMA;
 
    // number of backoff slots to be decremented after DIFS phase. 0 to disable BO.
    // A random BO avoids collisions in the case where two or more nodes start the CSMA
    // process at the same time. 
    uint8_t backoffMax;
    
    // number of CADs to estimate a clear CH
    uint8_t difsSlots;
 
    // available channel frequencies from list passed during OTA activation
    LoRaWANChannel_t availableChannels[2][RADIOLIB_LORAWAN_NUM_AVAILABLE_CHANNELS];
 
    // currently configured channels for TX and RX1
    LoRaWANChannel_t currentChannels[2] = { RADIOLIB_LORAWAN_CHANNEL_NONE, RADIOLIB_LORAWAN_CHANNEL_NONE };
 
    // currently configured datarates for TX and RX1
    uint8_t dataRates[2] = { RADIOLIB_LORAWAN_DATA_RATE_UNUSED, RADIOLIB_LORAWAN_DATA_RATE_UNUSED };
 
    // LoRaWAN revision (1.0 vs 1.1)
    uint8_t rev = 0;
 
    // timestamp to measure the RX1/2 delay (from uplink end)
    uint32_t rxDelayStart = 0;
 
    // timestamp when the Rx1/2 windows were closed (timeout or uplink received)
    uint32_t rxDelayEnd = 0;
 
    // delays between the uplink and RX1/2 windows
    uint32_t rxDelays[2] = { RADIOLIB_LORAWAN_RECEIVE_DELAY_1_MS, RADIOLIB_LORAWAN_RECEIVE_DELAY_2_MS };
 
    // device status - battery level
    uint8_t battLevel = 0xFF;
 
    // indicates whether an uplink has MAC commands as payload
    bool isMACPayload = false;
 
#if !defined(RADIOLIB_EEPROM_UNSUPPORTED)
    int16_t saveFcntUp();
 
    int16_t restoreFcntUp();
#endif
 
    // wait for, open and listen during Rx1 and Rx2 windows; only performs listening
    int16_t downlinkCommon();
 
    // method to generate message integrity code
    uint32_t generateMIC(uint8_t* msg, size_t len, uint8_t* key);
 
    // method to verify message integrity code
    // it assumes that the MIC is the last 4 bytes of the message
    bool verifyMIC(uint8_t* msg, size_t len, uint8_t* key);
 
    // configure the common physical layer properties (preamble, sync word etc.)
    // channels must be configured separately by setupChannels()!
    int16_t setPhyProperties();
 
    // setup uplink/downlink channel data rates and frequencies
    // will attempt to randomly select based on currently used band plan
    int16_t setupChannels(uint8_t* cfList);
 
    // select a set of semi-random TX/RX channels for the join-request and -accept message
    int16_t selectChannelsJR(uint16_t devNonce, uint8_t drJoinSubband);
 
    // select a set of random TX/RX channels for up- and downlink
    int16_t selectChannels();
 
    // find the first usable data rate for the given band
    int16_t findDataRate(uint8_t dr, DataRate_t* dataRate);
 
    // configure channel based on cached data rate ID and frequency
    int16_t configureChannel(uint8_t dir);
 
    // save all available channels to persistent storage
    int16_t saveChannels();
 
    // restore all available channels from persistent storage
    int16_t restoreChannels();
 
    // push MAC command to queue, done by copy
    int16_t pushMacCommand(LoRaWANMacCommand_t* cmd, LoRaWANMacCommandQueue_t* queue);
 
    // delete a specific MAC command from queue, indicated by the command ID
    int16_t deleteMacCommand(uint8_t cid, LoRaWANMacCommandQueue_t* queue);
 
    // execute mac command, return the number of processed bytes for sequential processing
    size_t execMacCommand(LoRaWANMacCommand_t* cmd);
    
    // Performs CSMA as per LoRa Alliance Technical Reccomendation 13 (TR-013).
    void performCSMA();
 
    // perform a single CAD operation for the under SF/CH combination. Returns either busy or otherwise.
    bool performCAD();
 
    // function to encrypt and decrypt payloads
    void processAES(uint8_t* in, size_t len, uint8_t* key, uint8_t* out, uint32_t fcnt, uint8_t dir, uint8_t ctrId, bool counter);
 
    // network-to-host conversion method - takes data from network packet and converts it to the host endians
    template<typename T>
    static T ntoh(uint8_t* buff, size_t size = 0);
 
    // host-to-network conversion method - takes data from host variable and and converts it to network packet endians
    template<typename T>
    static void hton(uint8_t* buff, T val, size_t size = 0);
};
 
#endif