Example with library lmic for stm32 https://github.com/mcci-catena/arduino-lmic

lorawan_example_rak811.ino

/*******************************************************************************
 * Copyright (c) 2015 Thomas Telkamp and Matthijs Kooijman
 *
 * Permission is hereby granted, free of charge, to anyone
 * obtaining a copy of this document and accompanying files,
 * to do whatever they want with them without any restriction,
 * including, but not limited to, copying, modification and redistribution.
 * NO WARRANTY OF ANY KIND IS PROVIDED.
 *
 * This example sends a valid LoRaWAN packet with payload "Hello,
 * world!", using frequency and encryption settings matching those of
 * the The Things Network.
 *
 * This uses OTAA (Over-the-air activation), where where a DevEUI and
 * application key is configured, which are used in an over-the-air
 * activation procedure where a DevAddr and session keys are
 * assigned/generated for use with all further communication.
 *
 * Note: LoRaWAN per sub-band duty-cycle limitation is enforced (1% in
 * g1, 0.1% in g2), but not the TTN fair usage policy (which is probably
 * violated by this sketch when left running for longer)!

 * To use this sketch, first register your application and device with
 * the things network, to set or generate an AppEUI, DevEUI and AppKey.
 * Multiple devices can use the same AppEUI, but each device has its own
 * DevEUI and AppKey.
 *
 * Do not forget to define the radio type correctly in config.h.
 *
 *******************************************************************************/

#include <lmic.h>
#include <hal/hal.h>
#include <SPI.h>


// This EUI must be in little-endian format, so least-significant-byte
// first. When copying an EUI from ttnctl output, this means to reverse
// the bytes. For TTN issued EUIs the last bytes should be 0xD5, 0xB3,
// 0x70.
static const u1_t PROGMEM APPEUI[8]= {0x23,0x87,0x94,0x20,0x40,0x89,0x37,0x56};
void os_getArtEui (u1_t* buf) { memcpy_P(buf, APPEUI, 8);}

// This should also be in little endian format, see above.
static const u1_t PROGMEM DEVEUI[8]= {0x89,0x67,0x45,0x23,0x43,0x65,0x87,0x09};
void os_getDevEui (u1_t* buf) { memcpy_P(buf, DEVEUI, 8);}

// This key should be in big endian format (or, since it is not really a
// number but a block of memory, endianness does not really apply). In
// practice, a key taken from the TTN console can be copied as-is.
static const u1_t PROGMEM APPKEY[16] = {0x98,0x76,0x54,0x56,0x78,0x90,0x32,0x92,0x48,0x93,0x40,0x32,0x49,0x82,0x34,0x89};
void os_getDevKey (u1_t* buf) {  memcpy_P(buf, APPKEY, 16);}

static uint8_t mydata[] = "Hello, world!";
static osjob_t sendjob;

// Schedule TX every this many seconds (might become longer due to duty
// cycle limitations).
const unsigned TX_INTERVAL = 20;
// LORA
#define RADIO_RESET_PORT        PB13
#define RADIO_MOSI_PORT         PA7
#define RADIO_MISO_PORT         PA6
#define RADIO_SCLK_PORT         PA5
#define RADIO_NSS_PORT          PB0
#define RADIO_DIO_0_PORT        PA11
#define RADIO_DIO_1_PORT        PB1
#define RADIO_DIO_2_PORT        PA3
#define RADIO_DIO_3_PORT        PH0
#define RADIO_DIO_4_PORT        PC13

#define RADIO_RF_CRX_RX                             PB_6  //CRF3 (ANT_SWITCH_TX_BOOST)
#define RADIO_RF_CBT_HF                             PB_7  //CRF2 HF (ANT_SWITCH_TX_RFO)
#define RADIO_RF_CTX_PA                             PA_4  //CRF1

// Pin mapping
const lmic_pinmap lmic_pins = {
    .nss = RADIO_NSS_PORT,
    .rxtx = RADIO_RF_CTX_PA,
    .rst = RADIO_RESET_PORT,
    .dio = {RADIO_DIO_0_PORT, RADIO_DIO_1_PORT, RADIO_DIO_2_PORT},
    // the RAK811 module needs PA_4 high for RX, low for TX???????
    //.rxtx_rx_active = 1,
};

void onEvent (ev_t ev) {
    Serial.print(os_getTime());
    Serial.print(": ");
    switch(ev) {
        case EV_SCAN_TIMEOUT:
            Serial.println(F("EV_SCAN_TIMEOUT"));
            break;
        case EV_BEACON_FOUND:
            Serial.println(F("EV_BEACON_FOUND"));
            break;
        case EV_BEACON_MISSED:
            Serial.println(F("EV_BEACON_MISSED"));
            break;
        case EV_BEACON_TRACKED:
            Serial.println(F("EV_BEACON_TRACKED"));
            break;
        case EV_JOINING:
            Serial.println(F("EV_JOINING"));
            break;
        case EV_JOINED:
            Serial.println(F("EV_JOINED"));
            {
              u4_t netid = 0;
              devaddr_t devaddr = 0;
              u1_t nwkKey[16];
              u1_t artKey[16];
              LMIC_getSessionKeys(&netid, &devaddr, nwkKey, artKey);
              Serial.print("netid: ");
              Serial.println(netid, DEC);
              Serial.print("devaddr: ");
              Serial.println(devaddr, HEX);
              Serial.print("artKey: ");
              for (int i=0; i<sizeof(artKey); ++i) {
                if (i != 0)
                  Serial.print("-");
                Serial.print(artKey[i], HEX);
              }
              Serial.println("");
              Serial.print("nwkKey: ");
              for (int i=0; i<sizeof(nwkKey); ++i) {
                      if (i != 0)
                              Serial.print("-");
                      Serial.print(nwkKey[i], HEX);
              }
              Serial.println("");

              LMIC_setSeqnoUp(140);
            }
            // Disable link check validation (automatically enabled
            // during join, but not supported by TTN at this time).
            LMIC_setLinkCheckMode(0);
            break;
        case EV_RFU1:
            Serial.println(F("EV_RFU1"));
            break;
        case EV_JOIN_FAILED:
            Serial.println(F("EV_JOIN_FAILED"));
            break;
        case EV_REJOIN_FAILED:
            Serial.println(F("EV_REJOIN_FAILED"));
            break;
            break;
        case EV_TXCOMPLETE:
            Serial.println(F("EV_TXCOMPLETE (includes waiting for RX windows)"));
            if (LMIC.txrxFlags & TXRX_ACK)
              Serial.println(F("Received ack"));
            if (LMIC.dataLen) {
              Serial.println(F("Received "));
              Serial.println(LMIC.dataLen);
              Serial.println(F(" bytes of payload"));
            }
            // Schedule next transmission
            os_setTimedCallback(&sendjob, os_getTime()+sec2osticks(TX_INTERVAL), do_send);
            break;
        case EV_LOST_TSYNC:
            Serial.println(F("EV_LOST_TSYNC"));
            break;
        case EV_RESET:
            Serial.println(F("EV_RESET"));
            break;
        case EV_RXCOMPLETE:
            // data received in ping slot
            Serial.println(F("EV_RXCOMPLETE"));
            break;
        case EV_LINK_DEAD:
            Serial.println(F("EV_LINK_DEAD"));
            break;
        case EV_LINK_ALIVE:
            Serial.println(F("EV_LINK_ALIVE"));
            break;
         default:
            Serial.println(F("Unknown event"));
            break;
    }
}

void do_send(osjob_t* j){
    // Check if there is not a current TX/RX job running
    if (LMIC.opmode & OP_TXRXPEND) {
        Serial.println(F("OP_TXRXPEND, not sending"));
    } else {
        // Prepare upstream data transmission at the next possible time.
        LMIC_setTxData2(1, mydata, sizeof(mydata)-1, 0);
        Serial.println(F("Packet queued"));
    }
    // Next TX is scheduled after TX_COMPLETE event.
}

void setup() {
    SPI.setMISO(RADIO_MISO_PORT);
    SPI.setMOSI(RADIO_MOSI_PORT);
    SPI.setSCLK(RADIO_SCLK_PORT);
    SPI.setSSEL(RADIO_NSS_PORT);
    Serial.begin(9600);
    Serial.println(F("Starting"));

    // LMIC init
    os_init();
    // Reset the MAC state. Session and pending data transfers will be discarded.
    LMIC_reset();

    LMIC_setLinkCheckMode(0);
    LMIC_setDrTxpow(DR_SF7,14);
    LMIC_selectSubBand(7);

    // Start job (sending automatically starts OTAA too)
    do_send(&sendjob);
}

void loop() {
    os_runloop_once();
}