File content as of revision 11:0cc0f7b84c72:

// License: Revised BSD License, see LICENSE.TXT, (c)2015 Semtech

#include "mbed.h"
#include "lmic.h"
#include "debug.h"

#define LORAWAN_NET_ID (uint32_t) 0x00000000
#define LORAWAN_DEV_ADDR (uint32_t) 0x00001056 // 0xA81F657A
#define LORAWAN_ADR_ON 1
#define LORAWAN_CONFIRMED_MSG_ON 1
#define LORAWAN_APP_PORT 15

static uint8_t NwkSKey[] = {
    0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
    0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF
//    0x6D, 0x0D, 0x54, 0x96, 0x79, 0xE7, 0x3D, 0x14, 
//    0x46, 0xA2, 0x88, 0x28, 0xC8, 0x7A, 0x85, 0x10
};

static uint8_t ArtSKey[] = {
    0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
    0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF
//    0xE9, 0x4D, 0x61, 0x65, 0x7D, 0x9C, 0xF7, 0xB2, 
//    0x6F, 0xB6, 0xED, 0x68, 0xF1, 0xD5, 0xD7, 0xA9
};

osjob_t initjob;
osjob_t sendFrameJob;
u1_t n = 0;

void os_getArtEui (uint8_t *buf) {} // ignore
void os_getDevEui (uint8_t *buf) {} // ignore
void os_getDevKey (uint8_t *buf) {} // ignore

void onSendFrame (osjob_t* j) {
    int frameLength = 32; // max 51?
    for (int i = 0; i < frameLength; i++) {
        LMIC.frame[i] = n++; // or any other payload
    }
//    LMIC.frame[0] = 'H';
//    LMIC.frame[1] = 'e';
//    LMIC.frame[2] = 'l';
//    LMIC.frame[3] = 'l';
//    LMIC.frame[4] = 'o';
    int result = LMIC_setTxData2(LORAWAN_APP_PORT, LMIC.frame, 
        frameLength, LORAWAN_CONFIRMED_MSG_ON); // calls onEvent()
}

void onInit (osjob_t* j) {
    LMIC_reset();
    LMIC_setAdrMode(LORAWAN_ADR_ON);
    LMIC_setDrTxpow(DR_SF12, 14);
    LMIC_setSession(LORAWAN_NET_ID, LORAWAN_DEV_ADDR, NwkSKey, ArtSKey);
    onSendFrame(NULL);
}

void onEvent (ev_t ev) { // called by lmic.cpp, see also oslmic.h
    debug_event(ev);
    if (ev == EV_TXCOMPLETE) {
        os_setCallback(&sendFrameJob, onSendFrame);
    }
}

int main (void) {
    debug_str("main\r\n");
    os_init();
    os_setCallback(&initjob, onInit);
    os_runloop(); // blocking
}