IBM LoRa MAC in C (LMiC) mbed library port

Dependents:   lora-temperature LoRaWAN-lmic-app_HS LoRaWAN-lmic-app_huynh

LoRa WAN in C for sx1276 shield

Currently version 1.5


LoRaWAN network configuration for end-device

The following three pieces of information uniquely identifies end-device to network to allow over-the-air activation. These are stored in the end-device prior to join procedure.

AppEUI

Uniquely identifies application provider of end-device.

Least-significant byte first, 8 bytes, use reverse memcpy() to keep same order as shown on lora server.

example C code

static const u1_t APPEUI[8]  = { 0x01, 0x00, 0x01, 0x00, 0x00, 0x0C, 0x25, 0x00 };

This is copied into LMIC by os_getArtEui() callback function in application.

DevEUI

End-device ID, unique to each end-node.

Least-significant byte first, 8 bytes, use reverse memcpy() to keep same order as shown on lora server.

example C code

static const u1_t DEVEUI[8]  = { 0x00, 0x00, 0x00, 0x00, 0x01, 0x0C, 0x25, 0x00 }; 

This is copied into LMIC by os_getDevEui() callback function in application.

AppKey (aka DevKey)

128-bit (16byte) AES key.

example C code

static const u1_t DEVKEY[16] = { 0xe4, 0x72, 0x71, 0xc5, 0xf5, 0x30, 0xa9, 0x9f, 0xcf, 0xc4, 0x0e, 0xab, 0xea, 0xd7, 0x19, 0x42 };

This is copied into LMIC by os_getDevKey() callback function in application.

Using over-the air activation, the end-device (LMIC) performs a join procedure every time it starts for first time, or has lost session context information. When join procedure has successfully completed, the end-device will have a network session key (NwkSKey) and an application session key (AppSKey), which are used for encryption and message integrity check.


US915 configuration with http://us01-iot.semtech.com/

  • log in to server
  • click on Applications
  • find your application and click it
  • go to configure motes
  • to create a mote, you may enter a new DevEUI
    • you may copy-paste the 16byte application key from an already existing mote, if you desire.
CHNL_HYBRID125KHz500KHz
defined valuechannelschannel
00 to 764
18 to 1565
216 to 2366
324 to 3167
432 to 3968
540 to 4769
648 to 5570
756 to 6371
undef0 to 6364 to 71
Revision:
0:62d1edcc13d1
Child:
1:d3b7bde3995c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lmic.cpp	Thu Jan 22 12:50:49 2015 +0000
@@ -0,0 +1,2078 @@
+/*******************************************************************************
+ * Copyright (c) 2014 IBM Corporation.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    IBM Zurich Research Lab - initial API, implementation and documentation
+ *******************************************************************************/
+
+#include "lmic.h"
+
+#define PAMBL_SYMS 8
+#define MINRX_SYMS 5
+#define PAMBL_FSK  5
+#define PRERX_FSK  1
+#define RXLEN_FSK  (1+5+2)
+
+#define BCN_INTV_osticks       sec2osticks(BCN_INTV_sec)
+#define TXRX_GUARD_osticks     ms2osticks(TXRX_GUARD_ms)
+#define JOIN_GUARD_osticks     ms2osticks(JOIN_GUARD_ms)
+#define DELAY_DNW1_osticks     sec2osticks(DELAY_DNW1)
+#define DELAY_DNW2_osticks     sec2osticks(DELAY_DNW2)
+#define DELAY_JACC1_osticks    sec2osticks(DELAY_JACC1)
+#define DELAY_JACC2_osticks    sec2osticks(DELAY_JACC2)
+#define DELAY_EXTDNW2_osticks  sec2osticks(DELAY_EXTDNW2)
+#define BCN_RESERVE_osticks    ms2osticks(BCN_RESERVE_ms)
+#define BCN_GUARD_osticks      ms2osticks(BCN_GUARD_ms)
+#define BCN_WINDOW_osticks     ms2osticks(BCN_WINDOW_ms)
+#define AIRTIME_BCN_osticks    us2osticks(AIRTIME_BCN)
+
+DEFINE_LMIC;
+DECL_ON_LMIC_EVENT;
+
+
+// Fwd decls.
+static void engineUpdate(void);
+static void startScan (void);
+
+
+// ================================================================================
+// BEG OS - default implementations for certain OS suport functions
+
+#if !HAS_os_calls
+
+#ifndef os_rlsbf2
+u2_t os_rlsbf2 (xref2cu1_t buf) {
+    return (u2_t)(buf[0] | (buf[1]<<8));
+}
+#endif
+
+#ifndef os_rlsbf4
+u4_t os_rlsbf4 (xref2cu1_t buf) {
+    return (u4_t)(buf[0] | (buf[1]<<8) | ((u4_t)buf[2]<<16) | ((u4_t)buf[3]<<24));
+}
+#endif
+
+
+#ifndef os_rmsbf4
+u4_t os_rmsbf4 (xref2cu1_t buf) {
+    return (u4_t)(buf[3] | (buf[2]<<8) | ((u4_t)buf[1]<<16) | ((u4_t)buf[0]<<24));
+}
+#endif
+
+
+#ifndef os_wlsbf2
+void os_wlsbf2 (xref2u1_t buf, u2_t v) {
+    buf[0] = v;
+    buf[1] = v>>8;
+}
+#endif
+
+#ifndef os_wlsbf4
+void os_wlsbf4 (xref2u1_t buf, u4_t v) {
+    buf[0] = v;
+    buf[1] = v>>8;
+    buf[2] = v>>16;
+    buf[3] = v>>24;
+}
+#endif
+
+#ifndef os_wmsbf4
+void os_wmsbf4 (xref2u1_t buf, u4_t v) {
+    buf[3] = v;
+    buf[2] = v>>8;
+    buf[1] = v>>16;
+    buf[0] = v>>24;
+}
+#endif
+
+#ifndef os_getBattLevel
+u1_t os_getBattLevel (void) {
+    return MCMD_DEVS_BATT_NOINFO;
+}
+#endif
+
+#ifndef os_crc16
+static const u2_t CRC_TABLE[] = {
+    0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
+    0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
+    0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
+    0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
+    0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
+    0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
+    0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
+    0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
+    0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
+    0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
+    0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
+    0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
+    0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
+    0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
+    0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
+    0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
+    0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
+    0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
+    0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
+    0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
+    0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
+    0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
+    0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
+    0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
+    0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
+    0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
+    0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
+    0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
+    0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
+    0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
+    0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
+    0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
+};
+u2_t os_crc16 (xref2u1_t data, uint len) {
+    u2_t fcs = 0;
+    for( uint u=0; u<len; u++ ) {
+    u1_t b = data[u];
+    fcs = (CRC_TABLE[(fcs ^ b) & 0xFF] ^ ((fcs >> 8) & 0xFF));
+    }
+    return fcs;
+}
+#endif
+
+#endif // !HAS_os_calls
+
+// END OS - default implementations for certain OS suport functions
+// ================================================================================
+
+// ================================================================================
+// BEG AES
+
+static void micB0 (u4_t devaddr, u4_t seqno, int dndir, int len) {
+    os_clearMem(AESaux,16);
+    AESaux[0]  = 0x49;
+    AESaux[5]  = dndir?1:0;
+    AESaux[15] = len;
+    os_wlsbf4(AESaux+ 6,devaddr);
+    os_wlsbf4(AESaux+10,seqno);
+}
+
+
+static int aes_verifyMic (xref2cu1_t key, u4_t devaddr, u4_t seqno, int dndir, xref2u1_t pdu, int len) {
+    micB0(devaddr, seqno, dndir, len);
+    os_copyMem(AESkey,key,16);
+    return os_aes(AES_MIC, pdu, len) == os_rmsbf4(pdu+len);
+}
+
+
+static void aes_appendMic (xref2cu1_t key, u4_t devaddr, u4_t seqno, int dndir, xref2u1_t pdu, int len) {
+    micB0(devaddr, seqno, dndir, len);
+    os_copyMem(AESkey,key,16);
+    // MSB because of internal structure of AES
+    os_wmsbf4(pdu+len, os_aes(AES_MIC, pdu, len));
+}
+
+
+static void aes_appendMic0 (xref2u1_t pdu, int len) {
+    os_getDevKey(AESkey);
+    os_wmsbf4(pdu+len, os_aes(AES_MIC|AES_MICNOAUX, pdu, len));  // MSB because of internal structure of AES
+}
+
+
+static int aes_verifyMic0 (xref2u1_t pdu, int len) {
+    os_getDevKey(AESkey);
+    return os_aes(AES_MIC|AES_MICNOAUX, pdu, len) == os_rmsbf4(pdu+len);
+}
+
+
+static void aes_encrypt (xref2u1_t pdu, int len) {
+    os_getDevKey(AESkey);
+    os_aes(AES_ENC, pdu, len);
+}
+
+
+static void aes_cipher (xref2cu1_t key, u4_t devaddr, u4_t seqno, int dndir, xref2u1_t payload, int len) {
+    if( len <= 0 )
+    return;
+    os_clearMem(AESaux, 16);
+    AESaux[0] = AESaux[15] = 1; // mode=cipher / dir=down / block counter=1
+    AESaux[5] = dndir?1:0;
+    os_wlsbf4(AESaux+ 6,devaddr);
+    os_wlsbf4(AESaux+10,seqno);
+    os_copyMem(AESkey,key,16);
+    os_aes(AES_CTR, payload, len);
+}
+
+
+static void aes_sessKeys (u2_t devnonce, xref2cu1_t artnonce, xref2u1_t nwkkey, xref2u1_t artkey) {
+    os_clearMem(nwkkey, 16);
+    nwkkey[0] = 0x01;
+    os_copyMem(nwkkey+1, artnonce, LEN_ARTNONCE+LEN_NETID);
+    os_wlsbf2(nwkkey+1+LEN_ARTNONCE+LEN_NETID, devnonce);
+    os_copyMem(artkey, nwkkey, 16);
+    artkey[0] = 0x02;
+
+    os_getDevKey(AESkey);
+    os_aes(AES_ENC, nwkkey, 16);
+    os_getDevKey(AESkey);
+    os_aes(AES_ENC, artkey, 16);
+}
+
+// END AES
+// ================================================================================
+
+
+// ================================================================================
+// BEG LORA
+
+#if CFG_eu868 // ========================================
+
+#define maxFrameLen(dr) ((dr)<=DR_SF9 ? maxFrameLens[(dr)] : 0xFF)
+const u1_t maxFrameLens [] = { 64,64,64,123 };
+
+const u1_t _DR2RPS_CRC[] = {
+    ILLEGAL_RPS,
+    (u1_t)MAKERPS(SF12, BW125, CR_4_5, 0, 0),
+    (u1_t)MAKERPS(SF11, BW125, CR_4_5, 0, 0),
+    (u1_t)MAKERPS(SF10, BW125, CR_4_5, 0, 0),
+    (u1_t)MAKERPS(SF9,  BW125, CR_4_5, 0, 0),
+    (u1_t)MAKERPS(SF8,  BW125, CR_4_5, 0, 0),
+    (u1_t)MAKERPS(SF7,  BW125, CR_4_5, 0, 0),
+    (u1_t)MAKERPS(SF7,  BW250, CR_4_5, 0, 0),
+    (u1_t)MAKERPS(FSK,  BW125, CR_4_5, 0, 0),
+    ILLEGAL_RPS
+};
+
+static const s1_t TXPOWLEVELS[] = {
+    20, 14, 11, 8, 5, 2, 0,0, 0,0,0,0, 0,0,0,0
+};
+#define pow2dBm(mcmd_ladr_p1) (TXPOWLEVELS[(mcmd_ladr_p1&MCMD_LADR_POW_MASK)>>MCMD_LADR_POW_SHIFT])
+
+#elif CFG_us915 // ========================================
+
+#define maxFrameLen(dr) ((dr)<=DR_SF11CR ? maxFrameLens[(dr)] : 0xFF)
+const u1_t maxFrameLens [] = { 24,66,142,255,255,255,255,255,  66,142 };
+
+const u1_t _DR2RPS_CRC[] = {
+    ILLEGAL_RPS,
+    MAKERPS(SF10, BW125, CR_4_5, 0, 0),
+    MAKERPS(SF9 , BW125, CR_4_5, 0, 0),
+    MAKERPS(SF8 , BW125, CR_4_5, 0, 0),
+    MAKERPS(SF7 , BW125, CR_4_5, 0, 0),
+    MAKERPS(SF8 , BW500, CR_4_5, 0, 0),
+    ILLEGAL_RPS ,
+    ILLEGAL_RPS ,
+    ILLEGAL_RPS ,
+    MAKERPS(SF12, BW500, CR_4_5, 0, 0),
+    MAKERPS(SF11, BW500, CR_4_5, 0, 0),
+    MAKERPS(SF10, BW500, CR_4_5, 0, 0),
+    MAKERPS(SF9 , BW500, CR_4_5, 0, 0),
+    MAKERPS(SF8 , BW500, CR_4_5, 0, 0),
+    MAKERPS(SF7 , BW500, CR_4_5, 0, 0),
+    ILLEGAL_RPS
+};
+
+#define pow2dBm(mcmd_ladr_p1) ((s1_t)(30 - (((mcmd_ladr_p1)&MCMD_LADR_POW_MASK)<<1)))
+
+#endif // ================================================
+
+static const u1_t SENSITIVITY[7][3] = {
+    // ------------bw----------
+    // 125kHz    250kHz    500kHz
+    { 141-109,  141-109, 141-109 },  // FSK
+    { 141-127,  141-124, 141-121 },  // SF7
+    { 141-129,  141-126, 141-123 },  // SF8
+    { 141-132,  141-129, 141-126 },  // SF9
+    { 141-135,  141-132, 141-129 },  // SF10
+    { 141-138,  141-135, 141-132 },  // SF11
+    { 141-141,  141-138, 141-135 }   // SF12
+};
+
+int getSensitivity (rps_t rps) {
+    return -141 + SENSITIVITY[getSf(rps)][getBw(rps)];
+}
+
+ostime_t calcAirTime (rps_t rps, u1_t plen) {
+    u1_t bw = getBw(rps);  // 0,1,2 = 125,250,500kHz
+    u1_t sf = getSf(rps);  // 0=FSK, 1..6 = SF7..12
+    if( sf == FSK ) {
+    // MLu - 12012015
+    return (plen+/*preamble*/5+/*syncword*/3+/*len*/1+/*crc*/2) * /*bits/byte*/8
+        * (s4_t)OSTICKS_PER_SEC / /*kbit/s*/50000;
+    //return (plen+/*preamble*/5+/*syncword*/2+/*len*/1+/*crc*/2) * /*bits/byte*/8
+    //    * (s4_t)OSTICKS_PER_SEC / /*kbit/s*/50000;
+    }
+    u1_t sfx = 4*(sf+(7-SF7));
+    u1_t q = sfx - (sf >= SF11 ? 8 : 0);
+    int tmp = 8*plen - sfx + 28 + (getNocrc(rps)?0:16) - (getIh(rps)?20:0);
+    if( tmp > 0 ) {
+    tmp = (tmp + q - 1) / q;
+    tmp *= getCr(rps)+5;
+    tmp += 8;
+    } else {
+    tmp = 8;
+    }
+    tmp = (tmp<<2) + /*preamble*/49 /* 4 * (8 + 4.25) */;
+    // bw = 125000 = 15625 * 2^3
+    //      250000 = 15625 * 2^4
+    //      500000 = 15625 * 2^5
+    // sf = 7..12
+    //
+    // osticks =  tmp * OSTICKS_PER_SEC * 1<<sf / bw
+    //
+    // 3 => counter reduced divisor 125000/8 => 15625
+    // 2 => counter 2 shift on tmp
+    sfx = sf+(7-SF7) - (3+2) - bw;
+    int div = 15625;
+    if( sfx > 4 ) {
+    // prevent 32bit signed int overflow in last step
+    div >>= sfx-4;
+    sfx = 4;
+    }
+    // Need 32bit arithmetic for this last step
+    return (((ostime_t)tmp << sfx) * OSTICKS_PER_SEC + div/2) / div;
+}
+
+extern inline s1_t  rssi2s1 (int v);
+extern inline int   s12rssi (s1_t v);
+extern inline float  s12snr (s1_t v);
+extern inline s1_t   snr2s1 (double v);
+extern inline int   getRssi (rxqu_t*rxq);
+extern inline void  setRssi (rxqu_t*rxq, int v);
+
+extern inline rps_t updr2rps (dr_t dr);
+extern inline rps_t dndr2rps (dr_t dr);
+extern inline int isFasterDR (dr_t dr1, dr_t dr2);
+extern inline int isSlowerDR (dr_t dr1, dr_t dr2);
+extern inline dr_t  incDR    (dr_t dr);
+extern inline dr_t  decDR    (dr_t dr);
+extern inline dr_t  assertDR (dr_t dr);
+extern inline dr_t  validDR  (dr_t dr);
+extern inline dr_t  lowerDR  (dr_t dr, u1_t n);
+
+extern inline sf_t  getSf    (rps_t params);
+extern inline rps_t setSf    (rps_t params, sf_t sf);
+extern inline bw_t  getBw    (rps_t params);
+extern inline rps_t setBw    (rps_t params, bw_t cr);
+extern inline cr_t  getCr    (rps_t params);
+extern inline rps_t setCr    (rps_t params, cr_t cr);
+extern inline int   getNocrc (rps_t params);
+extern inline rps_t setNocrc (rps_t params, int nocrc);
+extern inline int   getIh    (rps_t params);
+extern inline rps_t setIh    (rps_t params, int ih);
+extern inline rps_t makeRps  (sf_t sf, bw_t bw, cr_t cr, int ih, int nocrc);
+extern inline int   sameSfBw (rps_t r1, rps_t r2);
+
+// END LORA
+// ================================================================================
+
+
+// Adjust DR for TX retries
+//  - indexed by retry count
+//  - return steps to lower DR
+static const u1_t DRADJUST[2+TXCONF_ATTEMPTS] = {
+    // normal frames - 1st try / no retry
+    0,
+    // confirmed frames
+    0,0,0,0,0,1,1,1,2
+};
+
+
+// Table below defines the size of one symbol as
+//   symtime = 256us * 2^T(sf,bw)
+// 256us is called one symunit. 
+//                 SF:                      
+//      BW:     |__7___8___9__10__11__12
+//      125kHz     |  2   3   4   5   6   7
+//      250kHz     |  1   2   3   4   5   6
+//      500kHz     |  0   1   2   3   4   5
+//  
+// Times for half symbol per DR
+// Per DR table to minimize rounding errors
+static const ostime_t DR2HSYM_osticks[] = {
+#if CFG_eu868
+#define dr2hsym(dr) (DR2HSYM_osticks[(dr)])
+    us2osticksRound(128<<7),  // DR_SF12
+    us2osticksRound(128<<6),  // DR_SF11
+    us2osticksRound(128<<5),  // DR_SF10
+    us2osticksRound(128<<4),  // DR_SF9
+    us2osticksRound(128<<3),  // DR_SF8
+    us2osticksRound(128<<2),  // DR_SF7
+    us2osticksRound(128<<1),  // DR_SF7B
+    us2osticksRound(80)       // FSK -- not used (time for 1/2 byte)
+#elif CFG_us915
+#define dr2hsym(dr) (DR2HSYM_osticks[(dr)&7])  // map DR_SFnCR -> 0-6
+    us2osticksRound(128<<5),  // DR_SF10   DR_SF12CR
+    us2osticksRound(128<<4),  // DR_SF9    DR_SF11CR
+    us2osticksRound(128<<3),  // DR_SF8    DR_SF10CR
+    us2osticksRound(128<<2),  // DR_SF7    DR_SF9CR
+    us2osticksRound(128<<1),  // DR_SF8C   DR_SF8CR
+    us2osticksRound(128<<0)   // ------    DR_SF7CR
+#endif
+};
+
+
+static ostime_t calcRxWindow (u1_t secs, dr_t dr) {
+    ostime_t rxoff, err;
+    if( secs==0 ) {
+    // aka 128 secs (next becaon)
+    rxoff = LMIC.drift;
+    err = LMIC.lastDriftDiff;
+    } else {
+    // scheduled RX window within secs into current beacon period
+    rxoff = (LMIC.drift * (ostime_t)secs) >> BCN_INTV_exp;
+    err = (LMIC.lastDriftDiff * (ostime_t)secs) >> BCN_INTV_exp;
+    }
+    u1_t rxsyms = MINRX_SYMS;
+    err += (ostime_t)LMIC.maxDriftDiff * LMIC.missedBcns;
+    LMIC.rxsyms = MINRX_SYMS + (err / dr2hsym(dr));
+
+    return (rxsyms-PAMBL_SYMS) * dr2hsym(dr) + rxoff;
+}
+
+
+// Setup beacon RX parameters assuming we have an error of ms (aka +/-(ms/2))
+static void calcBcnRxWindowFromMillis (u1_t ms, bit_t ini) {
+    if( ini ) {
+    LMIC.drift = 0;
+    LMIC.maxDriftDiff = 0;
+    LMIC.missedBcns = 0;
+    LMIC.bcninfo.flags |= BCN_NODRIFT|BCN_NODDIFF;
+    }
+    ostime_t hsym = dr2hsym(DR_BCN);
+    LMIC.bcnRxsyms = MINRX_SYMS + ms2osticksCeil(ms) / hsym;
+    LMIC.bcnRxtime = LMIC.bcninfo.txtime + BCN_INTV_osticks - (LMIC.bcnRxsyms-PAMBL_SYMS) * hsym;
+}
+
+
+// Setup scheduled RX window (ping/multicast slot)
+static void rxschedInit (xref2rxsched_t rxsched) {
+    os_clearMem(AESkey,16);
+    os_clearMem(LMIC.frame+8,8);
+    os_wlsbf4(LMIC.frame, LMIC.bcninfo.time);
+    os_wlsbf4(LMIC.frame+4, LMIC.devaddr);
+    os_aes(AES_ENC,LMIC.frame,16);
+    u1_t intvExp = rxsched->intvExp;
+    ostime_t off = os_rlsbf2(LMIC.frame) & (0x0FFF >> (7 - intvExp)); // random offset (slot units)
+    rxsched->rxbase = (LMIC.bcninfo.txtime +
+               BCN_RESERVE_osticks +
+               ms2osticks(BCN_SLOT_SPAN_ms * off)); // random offset osticks
+    rxsched->slot   = 0;
+    rxsched->rxtime = rxsched->rxbase - calcRxWindow(/*secs BCN_RESERVE*/2+(1<<intvExp),rxsched->dr);
+    rxsched->rxsyms = LMIC.rxsyms;
+}
+
+
+static bit_t rxschedNext (xref2rxsched_t rxsched, ostime_t cando) {
+  again:
+    if( rxsched->rxtime - cando >= 0 )
+    return 1;
+    u1_t slot;
+    if( (slot=rxsched->slot) >= 128 )
+    return 0;
+    u1_t intv = 1<<rxsched->intvExp;
+    if( (rxsched->slot = (slot += (intv))) >= 128 )
+    return 0;
+    rxsched->rxtime = rxsched->rxbase
+    + ((BCN_WINDOW_osticks * (ostime_t)slot) >> BCN_INTV_exp)
+    - calcRxWindow(/*secs BCN_RESERVE*/2+slot+intv,rxsched->dr);
+    rxsched->rxsyms = LMIC.rxsyms;
+    goto again;
+}
+
+
+static ostime_t rndDelay (u1_t secSpan) {
+    u2_t r = os_getRndU2();
+    ostime_t delay = r;
+    if( delay > OSTICKS_PER_SEC )
+    delay = r % (u2_t)OSTICKS_PER_SEC;
+    if( secSpan > 0 )
+    delay += ((u1_t)r % secSpan) * OSTICKS_PER_SEC;
+    return delay;
+}
+
+
+static void txDelay (ostime_t reftime, u1_t secSpan) {
+    reftime += rndDelay(secSpan);
+    if( LMIC.globalDutyRate == 0  ||  (reftime - LMIC.globalDutyAvail) > 0 ) {
+    LMIC.globalDutyAvail = reftime;
+    LMIC.opmode |= OP_RNDTX;
+    }
+}
+
+
+static void setDrJoin (u1_t reason, u1_t dr) {
+    EV(drChange, INFO, (e_.reason    = reason,
+            e_.deveui    = MAIN::CDEV->getEui(),
+            e_.dr        = dr|DR_PAGE,
+            e_.txpow     = LMIC.adrTxPow,
+            e_.prevdr    = LMIC.datarate|DR_PAGE,
+            e_.prevtxpow = LMIC.adrTxPow));
+    LMIC.datarate = dr;
+    DO_DEVDB(updateDatarate, dr);
+}
+
+
+static void setDrTxpow (u1_t reason, u1_t dr, s1_t pow) {
+    EV(drChange, INFO, (e_.reason    = reason,
+            e_.deveui    = MAIN::CDEV->getEui(),
+            e_.dr        = dr|DR_PAGE,
+            e_.txpow     = pow,
+            e_.prevdr    = LMIC.datarate|DR_PAGE,
+            e_.prevtxpow = LMIC.adrTxPow));
+    if( pow != KEEP_TXPOW )
+    LMIC.adrTxPow = pow;
+    LMIC.datarate = dr;
+    DO_DEVDB(updateDatarate, dr);
+    LMIC.opmode |= OP_NEXTCHNL;
+}
+
+
+void LMIC_stopPingable (void) {
+    LMIC.opmode &= ~(OP_PINGABLE|OP_PINGINI);
+}
+
+
+void LMIC_setPingable (u1_t intvExp) {
+    // Change setting
+    LMIC.ping.intvExp = (intvExp & 0x7);
+    LMIC.opmode |= OP_PINGABLE;
+    // App may call LMIC_enableTracking() explicitely before
+    // Otherwise tracking is implicitly enabled here
+    if( (LMIC.opmode & (OP_TRACK|OP_SCAN)) == 0  &&  LMIC.bcninfoTries == 0 )
+    LMIC_enableTracking(0);
+}
+
+
+#if CFG_eu868
+// ================================================================================
+//
+// BEG: EU868 related stuff
+//
+enum { BAND_MILLI=0, BAND_CENTI=1, BAND_DECI=2 };
+static const u4_t iniChannelFreq[12] = {
+    // Join frequencies and duty cycle limit (0.1%)
+    EU868_F1|BAND_MILLI, EU868_F2|BAND_MILLI, EU868_F3|BAND_MILLI,
+    EU868_J4|BAND_MILLI, EU868_J5|BAND_MILLI, EU868_J6|BAND_MILLI,
+    // Default operational frequencies
+    EU868_F1|BAND_CENTI, EU868_F2|BAND_CENTI, EU868_F3|BAND_CENTI,
+    EU868_F4|BAND_MILLI, EU868_F5|BAND_MILLI, EU868_F6|BAND_DECI
+};
+
+static void initDefaultChannels (bit_t join) {
+    LMIC.channelMap = 0x3F;
+    u1_t su = join ? 0 : 6;
+    for( u1_t fu=0; fu<6; fu++,su++ ) {
+    LMIC.channelFreq[fu] = iniChannelFreq[su];
+    LMIC.channelDrs[fu]  = DR_SF12 | (DR_SF7<<4);
+    }
+    if( !join )
+    LMIC.channelDrs[1] = DR_SF12 | (DR_FSK<<4);
+
+    LMIC.bands[BAND_MILLI].txcap = 1000;  // 0.1%
+    LMIC.bands[BAND_MILLI].txpow = 14;
+    LMIC.bands[BAND_CENTI].txcap = 100;   // 1%
+    LMIC.bands[BAND_CENTI].txpow = 14;
+    LMIC.bands[BAND_DECI ].txcap = 10;    // 10%
+    LMIC.bands[BAND_DECI ].txpow = 27;
+    LMIC.bands[BAND_MILLI].avail = 
+    LMIC.bands[BAND_CENTI].avail =
+    LMIC.bands[BAND_DECI ].avail = os_getTime();
+}
+
+static u4_t convFreq (xref2u1_t ptr) {
+    u4_t freq = (os_rlsbf4(ptr-1) >> 8) * 100;
+    if( freq >= EU868_FREQ_MIN && freq <= EU868_FREQ_MAX )
+    freq = 0;
+    return freq;
+}
+
+static bit_t setupChannel (u1_t chidx, u4_t freq, int drs) {
+    if( chidx >= MAX_CHANNELS )
+    return 0;
+    if( freq >= 869400000 && freq <= 869650000 )
+    freq |= BAND_DECI;  // 10% 27dBm
+    else if( (freq >= 868000000 && freq <= 868600000) ||
+         (freq >= 869700000 && freq <= 870000000)  )
+    freq |= BAND_CENTI;  // 1% 14dBm
+    //else 
+    //  freq |= BAND_MILLI;  // 0.1% 14dBm
+    LMIC.channelFreq[chidx] = freq;
+    LMIC.channelDrs [chidx] = drs < 0 ? (DR_SF12|(DR_SF7<<4)) : drs;
+    return 1;
+}
+
+static u1_t mapChannels (u1_t chpage, u2_t chmap) {
+    if( chpage != 0 || (chmap & ~((u2_t)(1<<MAX_CHANNELS)-1)) != 0 )
+    return 0;  // illegal input
+    for( u1_t chnl=0; chnl<MAX_CHANNELS; chnl++ ) {
+    if( (chmap & (1<<chnl)) != 0 && LMIC.channelFreq[chnl] == 0 )
+        chmap &= ~(1<<chnl); // ignore - channel is not defined
+    }
+    LMIC.channelMap = chmap;
+    return 1;
+}
+
+
+static void updateTx (ostime_t txbeg) {
+    u4_t freq = LMIC.channelFreq[LMIC.txChnl];
+    // Update global/band specific duty cycle stats
+    ostime_t airtime = calcAirTime(LMIC.rps, LMIC.dataLen);
+    // Update channel/global duty cycle stats
+    xref2band_t band = &LMIC.bands[freq & 0x3];
+    LMIC.freq  = freq & ~(u4_t)3;
+    LMIC.txpow = band->txpow;
+    band->avail = txbeg + airtime * band->txcap;
+    // Update obsolete avail's to prevent rollover
+    // (needed for devices that send rarely - e.g. once/twice a day)
+    for( u1_t b=0; b<MAX_BANDS; b++ ) {
+    if( LMIC.bands[b].avail - txbeg < 0 )
+        LMIC.bands[b].avail = txbeg;
+    }
+    if( LMIC.globalDutyRate != 0 )
+    LMIC.globalDutyAvail = txbeg + (airtime<<LMIC.globalDutyRate);
+}
+
+static ostime_t nextTx (ostime_t now) {
+    // If we do not find a suitable channel stop sending (misconfigured device)
+    ostime_t mintime = now + /*10h*/36000*OSTICKS_PER_SEC;
+    s1_t     bmask   = 0;
+    for( u1_t b=0; b<MAX_BANDS; b++ ) {
+    xref2band_t band = &LMIC.bands[b];
+    if( band->txcap == 0 ) // band not setup
+        continue;
+    if( now - band->avail >= 0 ) {
+        bmask = (bmask < 0 ? 0 : bmask) | (1<<b);
+    }
+    else if( mintime - band->avail > 0 ) {
+        mintime = band->avail;
+    }
+    }
+    if( bmask == 0 )
+    return mintime;
+    u1_t chnl, ccnt;
+    u2_t cset, mask;
+    chnl = cset = ccnt = 0;
+    mask = 1;
+    while( mask && mask <= LMIC.channelMap ) {
+    // Channel is enabled AND and in a ready band and can handle the datarate
+    if( (mask & LMIC.channelMap) != 0  &&  (bmask & (1 << (LMIC.channelFreq[chnl] & 0x3))) != 0) {
+        u1_t drs = LMIC.channelDrs[chnl];
+        if( !(isSlowerDR((dr_t)LMIC.datarate, (dr_t)(drs & 0xF)) ||   // lowest datarate
+          isFasterDR((dr_t)LMIC.datarate, (dr_t)(drs >>  4))) ) { // fastest datarate
+        cset |= mask;
+        ccnt++;
+        }
+    }
+    mask <<= 1;
+    chnl++;
+    }
+    if( ccnt == 0 ) // No eligible channel - misconfigured device?
+    return mintime;
+    ccnt = os_getRndU2() % ccnt;
+    mask = 1;
+    chnl = 0;
+    do {
+    if( (cset & mask) != 0 ) {
+        if( ccnt==0 ) {
+        LMIC.txChnl = chnl;
+        return now;
+        }
+        ccnt--;
+    }
+    mask <<= 1;
+    chnl++;
+    } while(1);
+}
+
+static void setBcnRxParams (void) {
+    LMIC.dataLen = 0;
+    LMIC.freq = LMIC.channelFreq[LMIC.bcnChnl] & ~(u4_t)3;
+    LMIC.rps  = setIh(setNocrc(dndr2rps((dr_t)DR_BCN),1),LEN_BCN);
+}
+
+#define setRx1Params() /*LMIC.freq/rps remain unchanged*/
+
+static void initJoinLoop (void) {
+    LMIC.txChnl = os_getRndU1() % 3;
+    LMIC.adrTxPow = 14;
+    setDrJoin(DRCHG_SET, DR_SF7);
+    initDefaultChannels(1);
+    ASSERT((LMIC.opmode & OP_NEXTCHNL)==0);
+    LMIC.txend = LMIC.bands[BAND_MILLI].avail;
+}
+
+
+static ostime_t nextJoinState (void) {
+    // Try 869.x and then 864.x with same DR
+    // If both fail try next lower datarate
+    LMIC.opmode &= ~OP_NEXTCHNL;
+    LMIC.txend = LMIC.bands[BAND_MILLI].avail;
+    if( LMIC.txChnl < 3 ) {
+    LMIC.txChnl += 3;
+    } else {
+    if( LMIC.datarate == DR_SF12 ) {
+        setDrJoin(DRCHG_NOJACC, DR_SF7);
+        // We tried one round of FSK..SF12
+        // Now pick new random channel and insert a random delay and try another round.
+        LMIC.txChnl = os_getRndU1() % 3;
+        if( LMIC.txCnt < 5 )
+        LMIC.txCnt += 1;
+        // Delay by 7,15,31,63,127,255 secs
+        return rndDelay((4<<LMIC.txCnt)-1) | 1;   // |1 - trigger EV_JOIN_FAILED event
+    }
+    LMIC.txChnl = LMIC.txChnl==5 ? 0 : LMIC.txChnl-2;
+    setDrJoin(DRCHG_NOJACC, decDR((dr_t)LMIC.datarate));
+    }
+    // Avoid collision with JOIN ACCEPT being sent by GW (but we missed it)
+    return 3*OSTICKS_PER_SEC;
+}
+
+//
+// END: EU868 related stuff
+//
+// ================================================================================
+#elif CFG_us915
+// ================================================================================
+//
+// BEG: US915 related stuff
+//
+
+static void initDefaultChannels (void) {
+    for( u1_t i=0; i<4; i++ )
+    LMIC.channelMap[i] = 0xFFFF;
+    LMIC.channelMap[4] = 0x00FF;
+}
+
+static u4_t convFreq (xref2u1_t ptr) {
+    u4_t freq = (os_rlsbf4(ptr-1) >> 8) * 100;
+    if( freq >= US915_FREQ_MIN && freq <= US915_FREQ_MAX )
+    freq = 0;
+    return freq;
+}
+
+static bit_t setupChannel (u1_t chidx, u4_t freq, int drs) {
+    if( chidx < 72 || chidx >= 72+MAX_XCHANNELS )
+    return 0; // channels 0..71 are hardwired
+    chidx -= 72;
+    LMIC.xchFreq[chidx] = freq;
+    LMIC.xchDrs[chidx] = drs < 0 ? (DR_SF10|(DR_SF8C<<4)) : drs;
+    LMIC.channelMap[chidx>>4] |= (1<<(chidx&0xF));
+    return 1;
+}
+
+
+static u1_t mapChannels (u1_t chpage, u2_t chmap) {
+    if( chpage == MCMD_LADR_CHP_125ON || chpage == MCMD_LADR_CHP_125OFF ) {
+    u2_t en125 = chpage == MCMD_LADR_CHP_125ON ? 0xFFFF : 0x0000;
+    for( u1_t u=0; u<4; u++ )
+        LMIC.channelMap[u] = en125;
+    LMIC.channelMap[64/16] = chmap;
+    } else {
+    if( chpage >= (72+MAX_XCHANNELS+15)/16 )
+        return 0;
+    LMIC.channelMap[chpage] = chmap;
+    }
+    return 1;
+}
+
+static void updateTx (ostime_t txbeg) {
+    u1_t chnl = LMIC.txChnl;
+    if( chnl < 64 ) {
+    LMIC.freq = US915_125kHz_UPFBASE + chnl*US915_125kHz_UPFSTEP;
+    LMIC.txpow = 30;
+    return;
+    }
+    LMIC.txpow = 26;
+    if( chnl < 64+8 ) {
+    LMIC.freq = US915_500kHz_UPFBASE + (chnl-64)*US915_500kHz_UPFSTEP;
+    } else {
+    ASSERT(chnl < 64+8+MAX_XCHANNELS);
+    LMIC.freq = LMIC.xchFreq[chnl-72];
+    }
+
+    // Update global duty cycle stats
+    if( LMIC.globalDutyRate != 0 ) {
+    ostime_t airtime = calcAirTime(LMIC.rps, LMIC.dataLen);
+    LMIC.globalDutyAvail = txbeg + (airtime<<LMIC.globalDutyRate);
+    }
+}
+
+// US does not have duty cycling - return now as earliest TX time
+#define nextTx(now) (_nextTx(),(now))
+static void _nextTx (void) {
+    u1_t  chnl  = LMIC.txChnl;
+    u1_t  cnt   = 0;
+    bit_t bw500 = (LMIC.datarate >= DR_SF8C);
+
+    if( (LMIC.chRnd & 0xF) == 0 ) {
+    chnl += LMIC.chRnd>>4;
+    LMIC.chRnd = os_getRndU1();
+    }
+    LMIC.chRnd--;
+  again:
+    chnl += 1;
+    if( bw500 ) {
+    // Only channels 64..71
+    chnl = 64+(chnl&0x7);
+    // At least one 500kHz channel must be enabled
+    // - otherwise MAC should not have used such a datarate
+    ASSERT((LMIC.channelMap[64/16]&0xFF)!=0x00);
+    if( ++cnt == 8 )
+        return; // no appropriate channel enabled stay where we are
+    } else {
+    // At least one 125kHz channel must be enabled
+    // - otherwise MAC should not have used DR_SF10-7
+    ASSERT((LMIC.channelMap[0]|LMIC.channelMap[1]|LMIC.channelMap[2]|LMIC.channelMap[3])!=0x0000);
+    chnl = chnl&0x3F;
+    if( ++cnt == 64 )
+        return; // no appropriate channel enabled stay where we are
+    }
+    if( (LMIC.channelMap[(chnl >> 4)] & (1<<(chnl&0xF))) == 0 )
+    goto again;  // not enabled
+    LMIC.txChnl = chnl;
+}
+
+static void setBcnRxParams (void) {
+    LMIC.dataLen = 0;
+    LMIC.freq = US915_500kHz_DNFBASE + LMIC.bcnChnl*US915_500kHz_DNFSTEP;
+    LMIC.rps  = setIh(setNocrc(dndr2rps((dr_t)DR_BCN),1),LEN_BCN);
+}
+
+#define setRx1Params(void) {                         \
+    LMIC.freq = US915_500kHz_DNFBASE + (LMIC.txChnl & 0x7) * US915_500kHz_DNFSTEP; \
+    if( /* TX datarate */LMIC.rxsyms < DR_SF8C )                \
+    LMIC.rxsyms += DR_SF10CR - DR_SF10;                \
+    else if( LMIC.rxsyms == DR_SF8C )                    \
+    LMIC.rxsyms = DR_SF7CR;                        \
+    LMIC.rps = dndr2rps(LMIC.rxsyms);                    \
+}
+
+static void initJoinLoop (void) {
+    LMIC.txChnl = os_getRndU1() & 0x3F;
+    LMIC.adrTxPow = 20;
+    ASSERT((LMIC.opmode & OP_NEXTCHNL)==0);
+    LMIC.txend = os_getTime();
+    setDrJoin(DRCHG_SET, DR_SF7);
+}
+
+static ostime_t nextJoinState (void) {
+    // Try the following:
+    //   SF7/8/9/10  on a random channel 0..63
+    //   SF8C        on a random channel 64..71
+    //
+    LMIC.opmode &= ~OP_NEXTCHNL;
+    LMIC.txend = os_getTime();
+    if( LMIC.datarate != DR_SF8C ) {
+    LMIC.txChnl = 64+(LMIC.txChnl&7);
+    LMIC.datarate = DR_SF8C;
+    } else {
+    LMIC.txChnl = os_getRndU1() & 0x3F;
+    LMIC.datarate = DR_SF7 - (LMIC.txCnt++ & 3);
+    if( (LMIC.txCnt & 3) == 0 ) {
+        // Tried SF10/SF8C
+        // Delay by 7,15,31,63,127,255 secs
+        return rndDelay((4<<(LMIC.txCnt>>2))-1) | 1;   // |1 - trigger EV_JOIN_FAILED event
+    }
+    }
+    // Always wait 500ms in case there was a TX and we just missed it.
+    // Sending immediately would not be picked up because GW is still busy txing missed frame.
+    return (OSTICKS_PER_SEC/2) & ~1;
+}
+
+//
+// END: US915 related stuff
+//
+// ================================================================================
+#else
+#error Unsupported frequency band!
+#endif
+
+
+static void runEngineUpdate (xref2osjob_t osjob) {
+    engineUpdate();
+}
+
+
+static void reportEvent (ev_t ev) {
+    EV(devCond, INFO, (e_.reason = EV::devCond_t::LMIC_EV,
+               e_.eui    = MAIN::CDEV->getEui(),
+               e_.info   = ev));
+    ON_LMIC_EVENT(ev);
+    engineUpdate();
+}
+
+
+static void stateJustJoined (void) {
+    LMIC.seqnoDn     = LMIC.seqnoUp = 0;
+    LMIC.rejoinCnt   = 0;
+    LMIC.dnConf      = LMIC.adrChanged = LMIC.ladrAns = LMIC.devsAns = 0;
+    LMIC.moreData    = LMIC.dn2Ans = LMIC.snchAns = LMIC.dutyCapAns = 0;
+    LMIC.pingSetAns  = 0;
+    LMIC.upRepeat    = 0;
+    LMIC.adrAckReq   = LINK_CHECK_INIT;
+    LMIC.dn2Dr       = DR_DNW2;
+    LMIC.dn2Freq     = FREQ_DNW2;
+    LMIC.bcnChnl     = CHNL_BCN;
+    LMIC.ping.freq   = FREQ_PING;
+    LMIC.ping.dr     = DR_PING;
+}
+
+
+// ================================================================================
+// Decoding frames
+
+
+// Decode beacon  - do not overwrite bcninfo unless we have a match!
+static int decodeBeacon (void) {
+    ASSERT(LMIC.dataLen == LEN_BCN); // implicit header RX guarantees this
+    xref2u1_t d = LMIC.frame;
+    if( os_rlsbf2(&d[OFF_BCN_CRC1]) != os_crc16(d, OFF_BCN_CRC1) )
+    return 0;   // first (common) part fails CRC check
+    // First set of fields is ok
+    u4_t bcnnetid = os_rlsbf4(&d[OFF_BCN_NETID]) & 0xFFFFFF;
+    if( bcnnetid != LMIC.netid )
+    return -1;  // not the beacon we're looking for
+
+    LMIC.bcninfo.flags &= ~(BCN_PARTIAL|BCN_FULL);
+    // Match - update bcninfo structure
+    os_copyMem((xref2u1_t)&LMIC.bcninfo.rxq, (xref2u1_t)&LMIC.rxq, SIZEOFEXPR(LMIC.rxq));
+    LMIC.bcninfo.txtime = LMIC.rxtime - AIRTIME_BCN_osticks;
+    LMIC.bcninfo.time   = os_rlsbf4(&d[OFF_BCN_TIME]);
+    LMIC.bcninfo.flags |= BCN_PARTIAL;
+
+    // Check 2nd set
+    if( os_rlsbf2(&d[OFF_BCN_CRC2]) != os_crc16(d,OFF_BCN_CRC2) )
+    return 1;
+    // Second set of fields is ok
+    LMIC.bcninfo.lat    = (s4_t)os_rlsbf4(&d[OFF_BCN_LAT-1]) >> 8; // read as signed 24-bit
+    LMIC.bcninfo.lon    = (s4_t)os_rlsbf4(&d[OFF_BCN_LON-1]) >> 8; // ditto
+    LMIC.bcninfo.info   = d[OFF_BCN_INFO];
+    LMIC.bcninfo.flags |= BCN_FULL;
+    return 2;
+}
+
+
+static bit_t decodeFrame (void) {
+    xref2u1_t d = LMIC.frame;
+    u1_t hdr    = d[0];
+    u1_t ftype  = hdr & HDR_FTYPE;
+    int  dlen   = LMIC.dataLen;
+    if( dlen < OFF_DAT_OPTS+4 ||
+    (hdr & HDR_MAJOR) != HDR_MAJOR_V1 ||
+    (ftype != HDR_FTYPE_DADN  &&  ftype != HDR_FTYPE_DCDN) ) {
+    // Basic sanity checks failed
+    EV(specCond, WARN, (e_.reason = EV::specCond_t::UNEXPECTED_FRAME,
+                e_.eui    = MAIN::CDEV->getEui(),
+                e_.info   = dlen < 4 ? 0 : os_rlsbf4(&d[dlen-4]),
+                e_.info2  = hdr + (dlen<<8)));
+      norx:
+    LMIC.dataLen = 0;
+    return 0;
+    }
+    // Validate exact frame length
+    // Note: device address was already read+evaluated in order to arrive here.
+    int  fct   = d[OFF_DAT_FCT];
+    u4_t addr  = os_rlsbf4(&d[OFF_DAT_ADDR]);
+    u4_t seqno = os_rlsbf2(&d[OFF_DAT_SEQNO]);
+    int  olen  = fct & FCT_OPTLEN;
+    int  ackup = (fct & FCT_ACK) != 0 ? 1 : 0;   // ACK last up frame
+    int  poff  = OFF_DAT_OPTS+olen;
+    int  pend  = dlen-4;  // MIC
+
+    if( addr != LMIC.devaddr ) {
+    EV(specCond, WARN, (e_.reason = EV::specCond_t::ALIEN_ADDRESS,
+                e_.eui    = MAIN::CDEV->getEui(),
+                e_.info   = addr,
+                e_.info2  = LMIC.devaddr));
+    goto norx;
+    }
+    if( poff > pend ) {
+    EV(specCond, ERR, (e_.reason = EV::specCond_t::CORRUPTED_FRAME,
+               e_.eui    = MAIN::CDEV->getEui(),
+               e_.info   = 0x1000000 + (poff-pend) + (fct<<8) + (dlen<<16)));
+    goto norx;
+    }
+
+    int port = -1;
+    int replayConf = 0;
+
+    if( pend > poff )
+    port = d[poff++];
+
+    seqno = LMIC.seqnoDn + (u2_t)(seqno - LMIC.seqnoDn);
+
+    if( !aes_verifyMic(LMIC.nwkKey, LMIC.devaddr, seqno, /*dn*/1, d, pend) ) {
+    EV(specCond, ERR, (e_.reason = EV::specCond_t::CORRUPTED_MIC,
+               e_.eui    = MAIN::CDEV->getEui(),
+               e_.info   = Base::lsbf4(&d[pend]),
+               e_.info2  = seqno));
+    goto norx;
+    }
+    if( seqno < LMIC.seqnoDn ) {
+    if( (s4_t)seqno > (s4_t)LMIC.seqnoDn ) {
+        EV(specCond, INFO, (e_.reason = EV::specCond_t::DNSEQNO_ROLL_OVER,
+                e_.eui    = MAIN::CDEV->getEui(),
+                e_.info   = LMIC.seqnoDn, 
+                e_.info2  = seqno));
+        goto norx;
+    }
+    if( seqno != LMIC.seqnoDn-1 || !LMIC.dnConf || ftype != HDR_FTYPE_DCDN ) {
+        EV(specCond, INFO, (e_.reason = EV::specCond_t::DNSEQNO_OBSOLETE,
+                e_.eui    = MAIN::CDEV->getEui(),
+                e_.info   = LMIC.seqnoDn, 
+                e_.info2  = seqno));
+        goto norx;
+    }
+    // Replay of previous sequence number allowed only if
+    // previous frame and repeated both requested confirmation
+    replayConf = 1;
+    }
+    else {
+    if( seqno > LMIC.seqnoDn ) {
+        EV(specCond, INFO, (e_.reason = EV::specCond_t::DNSEQNO_SKIP,
+                e_.eui    = MAIN::CDEV->getEui(),
+                e_.info   = LMIC.seqnoDn, 
+                e_.info2  = seqno));
+    }
+    LMIC.seqnoDn = seqno+1;  // next number to be expected
+    DO_DEVDB(updateSeqnoDn, LMIC.seqnoDn);
+    // DN frame requested confirmation - provide ACK once with next UP frame
+    LMIC.dnConf = (ftype == HDR_FTYPE_DCDN ? FCT_ACK : 0);
+    }
+
+    if( LMIC.dnConf || (fct & FCT_MORE) )
+    LMIC.opmode |= OP_POLL;
+
+    // We heard from network
+    LMIC.adrChanged = 0;
+    LMIC.adrAckReq = LINK_CHECK_INIT;
+
+    // Process OPTS
+    int m = LMIC.rxq.rssi - RSSI_OFF - getSensitivity(LMIC.rps);
+    LMIC.margin = m < 0 ? 0 : m > 254 ? 254 : m;
+
+    xref2u1_t opts = &d[OFF_DAT_OPTS];
+    int oidx = 0;
+    while( oidx < olen ) {
+    switch( opts[oidx] ) {
+    case MCMD_LCHK_ANS: {
+        //int gwmargin = opts[oidx+1];
+        //int ngws = opts[oidx+2];
+        oidx += 3;
+        continue;
+    }
+    case MCMD_LADR_REQ: {
+        u1_t p1     = opts[oidx+1];            // txpow + DR
+        u2_t chmap  = os_rlsbf2(&opts[oidx+2]);// list of enabled channel
+        u1_t chpage = opts[oidx+4] & MCMD_LADR_CHPAGE_MASK;     // channel page
+        u1_t uprpt  = opts[oidx+4] & MCMD_LADR_REPEAT_MASK;     // up repeat count
+        oidx += 5;
+
+        LMIC.ladrAns = 0x80 |     // Include an answer into next frame up
+        MCMD_LADR_ANS_POWACK | MCMD_LADR_ANS_CHACK | MCMD_LADR_ANS_DRACK;
+        if( !mapChannels(chpage, chmap) )
+        LMIC.ladrAns &= ~MCMD_LADR_ANS_CHACK;
+        dr_t dr = (dr_t)(p1>>MCMD_LADR_DR_SHIFT);
+        if( !validDR(dr) ) {
+        LMIC.ladrAns &= ~MCMD_LADR_ANS_DRACK;
+        dr = (dr_t)LMIC.datarate;
+        EV(specCond, ERR, (e_.reason = EV::specCond_t::BAD_MAC_CMD,
+                   e_.eui    = MAIN::CDEV->getEui(),
+                   e_.info   = Base::lsbf4(&d[pend]),
+                   e_.info2  = Base::msbf4(&opts[oidx-4])));
+        }
+        LMIC.upRepeat = uprpt;
+        setDrTxpow(DRCHG_NWKCMD, dr, pow2dBm(p1));
+        LMIC.adrChanged = 1;  // Trigger an ACK to NWK
+        continue;
+    }
+    case MCMD_DEVS_REQ: {
+        LMIC.devsAns = 1;
+        oidx += 1;
+        continue;
+    }
+    case MCMD_DN2P_SET: {
+        dr_t dr = (dr_t)(opts[oidx+1] & 0x0F);
+        u4_t freq = convFreq(&opts[oidx+2]);
+        oidx += 5;
+        LMIC.dn2Ans = 0x80;   // answer pending
+        if( validDR(dr) )
+        LMIC.dn2Ans |= MCMD_DN2P_ANS_DRACK;
+        if( freq != 0 )
+        LMIC.dn2Ans |= MCMD_DN2P_ANS_CHACK;
+        if( LMIC.dn2Ans == (0x80|MCMD_DN2P_ANS_DRACK|MCMD_DN2P_ANS_CHACK) ) {
+        LMIC.dn2Dr = dr;
+        LMIC.dn2Freq = freq;
+        DO_DEVDB(updateDn2,LMIC.dn2Dr,LMIC.dn2Freq);
+        }
+        continue;
+    }
+    case MCMD_DCAP_REQ: {
+        u1_t cap = opts[oidx+1];
+        oidx += 2;
+        // A value cap=0xFF means device is OFF unless enabled again manually
+        // We just set duty cap to 0xF which is 0.003% -- pretty much off.
+        // We don't check 0xF0 bits if cap!=0xFF
+        LMIC.globalDutyRate  = cap & 0xF;
+        LMIC.globalDutyAvail = os_getTime();
+        DO_DEVDB(updateDutyCap,cap);
+        LMIC.dutyCapAns = 1;
+        continue;
+    }
+    case MCMD_SNCH_REQ: {
+        u1_t chidx = opts[oidx+1];  // channel
+        u4_t freq  = convFreq(&opts[oidx+2]); // freq
+        u1_t drs   = opts[oidx+5];  // datarate span
+        LMIC.snchAns = 0x80;
+        if( freq != 0 && setupChannel(chidx,freq,drs) )
+        LMIC.snchAns |= MCMD_SNCH_ANS_DRACK|MCMD_SNCH_ANS_FQACK;
+        oidx += 6;
+    }
+    case MCMD_PING_SET: {
+        u4_t freq = convFreq(&opts[oidx+1]);
+        oidx += 4;
+        u1_t flags = 0x80;
+        if( freq != 0 ) {
+        flags |= MCMD_PING_ANS_FQACK;
+        LMIC.ping.freq = freq;
+        DO_DEVDB(updateClassB,LMIC.ping.intvExp,freq,LMIC.ping.dr);
+        }
+        LMIC.pingSetAns = flags;
+        continue;
+    }
+    case MCMD_BCNI_ANS: {
+        // Ignore if tracking already enabled
+        if( (LMIC.opmode & OP_TRACK) == 0 ) {
+        LMIC.bcnChnl = opts[oidx+3];
+        // Enable tracking - bcninfoTries
+        LMIC.opmode |= OP_TRACK;
+        // Cleared later in txComplete handling - triggers EV_BEACON_FOUND
+        ASSERT(LMIC.bcninfoTries!=0);
+        // Setup RX parameters
+        LMIC.bcninfo.txtime =  (LMIC.rxtime
+                       - calcAirTime(LMIC.rps, LMIC.dataLen)
+                       + ms2osticks(os_rlsbf2(&opts[oidx+1]) * 10)
+                       + ms2osticksCeil(5)
+                       - BCN_INTV_osticks);
+        LMIC.bcninfo.flags = 0;  // txtime above cannot be used as reference (BCN_PARTIAL|BCN_FULL cleared)
+        calcBcnRxWindowFromMillis(10,1);  // error of +/-5 ms 
+
+        EV(lostFrame, INFO, (e_.reason  = EV::lostFrame_t::MCMD_BCNI_ANS,
+                     e_.eui     = MAIN::CDEV->getEui(),
+                     e_.lostmic = Base::lsbf4(&d[pend]),
+                     e_.info    = (LMIC.missedBcns |
+                           (osticks2us(LMIC.bcninfo.txtime + BCN_INTV_osticks
+                                   - LMIC.bcnRxtime) << 8)),
+                     e_.time    = MAIN::CDEV->ostime2ustime(LMIC.bcninfo.txtime + BCN_INTV_osticks)));
+        }
+        oidx += 4;
+        continue;
+    }
+    }
+    EV(specCond, ERR, (e_.reason = EV::specCond_t::BAD_MAC_CMD,
+               e_.eui    = MAIN::CDEV->getEui(),
+               e_.info   = Base::lsbf4(&d[pend]),
+               e_.info2  = Base::msbf4(&opts[oidx])));
+    break;
+    }
+    if( oidx != olen ) {
+    EV(specCond, ERR, (e_.reason = EV::specCond_t::CORRUPTED_FRAME,
+               e_.eui    = MAIN::CDEV->getEui(),
+               e_.info   = 0x1000000 + (oidx) + (olen<<8)));
+    }
+
+    if( !replayConf ) {
+    // Handle payload only if not a replay
+    // Decrypt payload - if any
+    if( port >= 0  &&  pend-poff > 0 )
+        aes_cipher(port <= 0 ? LMIC.nwkKey : LMIC.artKey, LMIC.devaddr, seqno, /*dn*/1, d+poff, pend-poff);
+
+    EV(dfinfo, DEBUG, (e_.deveui  = MAIN::CDEV->getEui(),
+               e_.devaddr = LMIC.devaddr,
+               e_.seqno   = seqno,
+               e_.flags   = (port < 0 ? EV::dfinfo_t::NOPORT : 0) | EV::dfinfo_t::DN,
+               e_.mic     = Base::lsbf4(&d[pend]),
+               e_.hdr     = d[LORA::OFF_DAT_HDR],
+               e_.fct     = d[LORA::OFF_DAT_FCT],
+               e_.port    = port,
+               e_.plen    = dlen,
+               e_.olen    = olen,
+               memcpy(e_.opts, opts, olen)));
+    } else {
+    EV(specCond, INFO, (e_.reason = EV::specCond_t::DNSEQNO_REPLAY,
+                e_.eui    = MAIN::CDEV->getEui(),
+                e_.info   = Base::lsbf4(&d[pend]),
+                e_.info2  = seqno));
+    }
+
+    if( // NWK acks but we don't have a frame pending
+    (ackup && LMIC.txCnt == 0) ||
+    // We sent up confirmed and we got a response in DNW1/DNW2
+    // BUT it did not carry an ACK - this should never happen
+    // Do not resend and assume frame was not ACKed.
+    (!ackup && LMIC.txCnt != 0) ) {
+    EV(specCond, ERR, (e_.reason = EV::specCond_t::SPURIOUS_ACK,
+               e_.eui    = MAIN::CDEV->getEui(),
+               e_.info   = seqno,
+               e_.info2  = ackup));
+    }
+
+    if( LMIC.txCnt != 0 ) // we requested an ACK
+    LMIC.txrxFlags |= ackup ? TXRX_ACK : TXRX_NACK;
+
+    if( port < 0 ) {
+    LMIC.txrxFlags |= TXRX_NOPORT;
+    LMIC.dataBeg = LMIC.dataLen = 0;
+    } else {
+    LMIC.dataBeg = poff;
+    LMIC.dataLen = pend-poff;
+    }
+    return 1;
+}
+
+
+// ================================================================================
+// TX/RX transaction support
+
+
+static void setupRx2 (void) {
+    LMIC.txrxFlags = TXRX_DNW2;
+    LMIC.rps = dndr2rps(LMIC.dn2Dr);
+    LMIC.freq = LMIC.dn2Freq;
+    LMIC.dataLen = 0;
+    os_radio(RADIO_RX);
+}
+
+
+static void schedRx2 (ostime_t delay, osjobcb_t func) {
+    // Add 1.5 symbols we need 5 out of 8. Try to sync 1.5 symbols into the preamble.
+    LMIC.rxtime = LMIC.txend + delay + (PAMBL_SYMS-MINRX_SYMS)*dr2hsym(LMIC.dn2Dr);
+    os_setTimedCallback(&LMIC.osjob, LMIC.rxtime - RX_RAMPUP, func);
+}
+
+static void setupRx1 (osjobcb_t func) {
+    LMIC.txrxFlags = TXRX_DNW1;
+    // Turn LMIC.rps from TX over to RX
+    LMIC.rps = setNocrc(LMIC.rps,1);
+    LMIC.dataLen = 0;
+    LMIC.osjob.func = func;
+    os_radio(RADIO_RX);
+}
+
+
+// Called by HAL once TX complete and delivers exact end of TX time stamp in LMIC.rxtime
+static void txDone (ostime_t delay, osjobcb_t func) {
+    // NOTE: LMIC.rxsyms carries the modified DR for TX (LMIC.datarate is the base DR - [CONFIRM mode])
+    u1_t dr = LMIC.rxsyms;    // rxschedInit - would overwrite rxsyms
+    if( (LMIC.opmode & (OP_TRACK|OP_PINGABLE|OP_PINGINI)) == (OP_TRACK|OP_PINGABLE) ) {
+    rxschedInit(&LMIC.ping);    // note: reuses LMIC.frame buffer!
+    LMIC.opmode |= OP_PINGINI;
+    }
+    // Change RX frequency / rps (US only) before we increment txChnl
+    setRx1Params();
+    // LMIC.rxsyms carries the TX datarate (can be != LMIC.datarate [confirm retries etc.])
+    // Setup receive - LMIC.rxtime is preloaded with 1.5 symbols offset to tune
+    // into the middle of the 8 symbols preamble.
+#if CFG_eu868
+    if( /* TX datarate */LMIC.rxsyms == DR_FSK ) {
+    LMIC.rxtime = LMIC.txend + delay - PRERX_FSK*us2osticksRound(160);
+    LMIC.rxsyms = RXLEN_FSK;
+    }
+    else
+#endif
+    {
+    LMIC.rxtime = LMIC.txend + delay + (PAMBL_SYMS-MINRX_SYMS)*dr2hsym(dr);
+    LMIC.rxsyms = MINRX_SYMS;
+    }
+    os_setTimedCallback(&LMIC.osjob, LMIC.rxtime - RX_RAMPUP, func);
+}
+
+
+// ======================================== Join frames
+
+
+static void onJoinFailed (xref2osjob_t osjob) {
+    // Notify app - must call LMIC_reset() to stop joining
+    // otherwise join procedure continues.
+    reportEvent(EV_JOIN_FAILED);
+}
+
+
+static bit_t processJoinAccept (void) {
+    ASSERT(LMIC.txrxFlags != TXRX_DNW1 || LMIC.dataLen != 0);
+    ASSERT((LMIC.opmode & OP_TXRXPEND)!=0);
+
+    if( LMIC.dataLen == 0 ) {
+      nojoinframe:
+    if( (LMIC.opmode & OP_OTA) != 0 ) {
+    if( (LMIC.opmode & OP_JOINING) == 0 ) {
+        ASSERT((LMIC.opmode & OP_REJOIN) != 0);
+        // REJOIN attempt for roaming
+        LMIC.opmode &= ~(OP_REJOIN|OP_TXRXPEND);
+        if( LMIC.rejoinCnt < 10 )
+        LMIC.rejoinCnt++;
+        reportEvent(EV_REJOIN_FAILED);
+        return 1;
+    }
+    }
+    LMIC.opmode &= ~OP_TXRXPEND;
+    ostime_t delay = nextJoinState();
+    EV(devCond, DEBUG, (e_.reason = EV::devCond_t::NO_JACC,
+                e_.eui    = MAIN::CDEV->getEui(),
+                e_.info   = LMIC.datarate|DR_PAGE,
+                e_.info2  = osticks2ms(delay)));
+    // Build next JOIN REQUEST with next engineUpdate call
+    // Optionally, report join failed.
+    // Both after a random/chosen amount of ticks.
+    os_setTimedCallback(&LMIC.osjob, os_getTime()+delay,
+                (delay&1) != 0
+                ? FUNC_ADDR(onJoinFailed)      // one JOIN iteration done and failed
+                : FUNC_ADDR(runEngineUpdate)); // next step to be delayed
+    return 1;
+    }
+    u1_t hdr  = LMIC.frame[0];
+    u1_t dlen = LMIC.dataLen;
+    u4_t mic  = os_rlsbf4(&LMIC.frame[dlen-4]); // safe before modified by encrypt!
+    if( (dlen != LEN_JA && dlen != LEN_JAEXT)
+    || (hdr & (HDR_FTYPE|HDR_MAJOR)) != (HDR_FTYPE_JACC|HDR_MAJOR_V1) ) {
+    EV(specCond, ERR, (e_.reason = EV::specCond_t::UNEXPECTED_FRAME,
+               e_.eui    = MAIN::CDEV->getEui(),
+               e_.info   = dlen < 4 ? 0 : mic,
+               e_.info2  = hdr + (dlen<<8)));
+      badframe:
+    goto nojoinframe;
+    }
+    aes_encrypt(LMIC.frame+1, dlen-1);
+    if( !aes_verifyMic0(LMIC.frame, dlen-4) ) {
+    EV(specCond, ERR, (e_.reason = EV::specCond_t::JOIN_BAD_MIC,
+               e_.info   = mic));
+    goto badframe;
+    }
+
+    u4_t addr = os_rlsbf4(LMIC.frame+OFF_JA_DEVADDR);
+    LMIC.devaddr = addr;
+    LMIC.netid = os_rlsbf4(&LMIC.frame[OFF_BCN_NETID-1]) >> 8;
+
+#if CFG_eu868
+    initDefaultChannels(0);
+#endif
+    if( dlen > LEN_JA ) {
+    dlen = OFF_CFLIST;
+#if CFG_eu868
+    u1_t chidx=3;
+#elif CFG_us915
+    u1_t chidx=72;
+#endif
+    for( ; chidx<8; chidx++, dlen+=3 )
+        setupChannel(chidx, os_rlsbf4(&LMIC.frame[dlen-1]) >> 8, -1);
+    }
+
+    // already incremented when JOIN REQ got sent off
+    aes_sessKeys(LMIC.devNonce-1, &LMIC.frame[OFF_JA_ARTNONCE], LMIC.nwkKey, LMIC.artKey);
+    DO_DEVDB(updateJoinAcc, LMIC.devaddr, LMIC.nwkKey, LMIC.artKey);
+
+    EV(joininfo, INFO, (e_.arteui  = MAIN::CDEV->getArtEui(),
+            e_.deveui  = MAIN::CDEV->getEui(),
+            e_.devaddr = LMIC.devaddr,
+            e_.oldaddr = oldaddr,
+            e_.nonce   = LMIC.devNonce-1,
+            e_.mic     = mic,
+            e_.flags   = ((LMIC.opmode & OP_REJOIN) != 0
+                      ? EV::joininfo_t::REJOIN_ACCEPT
+                      : EV::joininfo_t::ACCEPT)));
+    
+    ASSERT((LMIC.opmode & (OP_JOINING|OP_REJOIN))!=0);
+    if( (LMIC.opmode & OP_REJOIN) != 0 ) {
+    LMIC.datarate = lowerDR(LMIC.datarate, LMIC.rejoinCnt);
+    }
+    LMIC.opmode &= ~(OP_JOINING|OP_TRACK|OP_REJOIN|OP_TXRXPEND|OP_PINGINI) | OP_NEXTCHNL;
+    stateJustJoined();
+    reportEvent(EV_JOINED);
+    return 1;
+}
+
+static void processRx1Jacc (xref2osjob_t osjob) {
+    if( LMIC.dataLen == 0 )
+    LMIC.txrxFlags = 0;  // nothing in 1st/2nd DN slot
+    processJoinAccept();
+}
+
+static void setupRx1Jacc (xref2osjob_t osjob) {
+    setupRx1(FUNC_ADDR(processRx1Jacc));
+}
+
+
+static void jreqDone (xref2osjob_t osjob) {
+    txDone(DELAY_JACC1_osticks, FUNC_ADDR(setupRx1Jacc));
+}
+
+// ======================================== Data frames
+
+// Fwd decl.
+static bit_t processDnData(void);
+
+static void processRx2DnData (xref2osjob_t osjob) {
+    if( LMIC.dataLen == 0 )
+    LMIC.txrxFlags = 0;  // nothing in 1st/2nd DN slot
+    processDnData();
+}
+
+
+static void setupRx2DnData (xref2osjob_t osjob) {
+    LMIC.osjob.func = FUNC_ADDR(processRx2DnData);
+    setupRx2();
+}
+
+
+static void processRx1DnData (xref2osjob_t osjob) {
+    if( LMIC.dataLen == 0 || !processDnData() )
+    schedRx2(DELAY_DNW2_osticks, FUNC_ADDR(setupRx2DnData));
+}
+
+
+static void setupRx1DnData (xref2osjob_t osjob) {
+    setupRx1(FUNC_ADDR(processRx1DnData));
+}
+
+
+static void updataDone (xref2osjob_t osjob) {
+    txDone(DELAY_DNW1_osticks, FUNC_ADDR(setupRx1DnData));
+}
+
+// ======================================== 
+
+
+static void buildDataFrame (void) {
+    bit_t txdata = ((LMIC.opmode & (OP_TXDATA|OP_POLL)) != OP_POLL);
+    u1_t dlen = txdata ? LMIC.pendTxLen : 0;
+
+    // Piggyback MAC options
+    // Prioritize by importance
+    int  end = OFF_DAT_OPTS;
+    if( (LMIC.opmode & (OP_TRACK|OP_PINGABLE)) == (OP_TRACK|OP_PINGABLE) ) {
+    // Indicate pingability in every UP frame
+    LMIC.frame[end] = MCMD_PING_IND;
+    LMIC.frame[end+1] = LMIC.ping.dr | (LMIC.ping.intvExp<<4);
+    end += 2;
+    }
+    if( LMIC.dutyCapAns ) {
+    LMIC.frame[end] = MCMD_DCAP_ANS;
+    end += 1;
+    LMIC.dutyCapAns = 0;
+    }
+    if( LMIC.dn2Ans ) {
+    LMIC.frame[end+0] = MCMD_DN2P_ANS;
+    LMIC.frame[end+1] = LMIC.dn2Ans & ~MCMD_DN2P_ANS_RFU;
+    end += 2;
+    LMIC.dn2Ans = 0;
+    }
+    if( LMIC.devsAns ) {  // answer to device status
+    LMIC.frame[end+0] = MCMD_DEVS_ANS;
+    LMIC.frame[end+1] = LMIC.margin;
+    LMIC.frame[end+2] = os_getBattLevel();
+    end += 3;
+    LMIC.devsAns = 0;
+    }
+    if( LMIC.ladrAns ) {  // answer to ADR change
+    LMIC.frame[end+0] = MCMD_LADR_ANS;
+    LMIC.frame[end+1] = LMIC.ladrAns & ~MCMD_LADR_ANS_RFU;
+    end += 2;
+    LMIC.ladrAns = 0;
+    }
+    if( LMIC.bcninfoTries > 0 ) {
+    LMIC.frame[end] = MCMD_BCNI_REQ;
+    end += 1;
+    }
+    if( LMIC.adrChanged ) {
+    LMIC.adrAckReq = LMIC.adrAckReq < 0 ? 0 : LMIC.adrAckReq;
+    LMIC.adrChanged = 0;
+    }
+    if( LMIC.pingSetAns != 0 ) {
+    LMIC.frame[end+0] = MCMD_PING_ANS;
+    LMIC.frame[end+1] = LMIC.pingSetAns & ~MCMD_PING_ANS_RFU;
+    end += 2;
+    LMIC.pingSetAns = 0;
+    }
+    if( LMIC.snchAns ) {
+    LMIC.frame[end+0] = MCMD_SNCH_ANS;
+    LMIC.frame[end+1] = LMIC.snchAns;
+    end += 2;
+    LMIC.snchAns = 0;
+    }
+    ASSERT(end <= OFF_DAT_OPTS+16);
+
+    u1_t flen = end + (txdata ? 5+dlen : 4);
+    if( flen > MAX_LEN_FRAME ) {
+    // Options and payload too big - delay payload
+    txdata = 0;
+    flen = end+4;
+    }
+    LMIC.frame[OFF_DAT_HDR] = HDR_FTYPE_DAUP | HDR_MAJOR_V1;
+    LMIC.frame[OFF_DAT_FCT] = (LMIC.dnConf | LMIC.adrEnabled
+                  | (LMIC.adrAckReq >= 0 ? FCT_ADRARQ : 0)
+                  | (end-OFF_DAT_OPTS));
+    os_wlsbf4(LMIC.frame+OFF_DAT_ADDR,  LMIC.devaddr);
+
+    if( LMIC.txCnt == 0 ) {
+    LMIC.seqnoUp += 1;
+    DO_DEVDB(updateSeqnoUp, LMIC.seqnoUp);
+    } else {
+    EV(devCond, INFO, (e_.reason = EV::devCond_t::RE_TX,
+               e_.eui    = MAIN::CDEV->getEui(),
+               e_.info   = LMIC.seqnoUp-1,
+               e_.info2  = (LMIC.txCnt+1) | (DRADJUST[LMIC.txCnt+1] << 8) | ((LMIC.datarate|DR_PAGE)<<16)));
+    }
+    os_wlsbf2(LMIC.frame+OFF_DAT_SEQNO, LMIC.seqnoUp-1);
+
+    // Clear pending DN confirmation
+    LMIC.dnConf = 0;
+
+    if( txdata ) {
+    if( LMIC.pendTxConf ) {
+        // Confirmed only makes sense if we have a payload (or at least a port)
+        LMIC.frame[OFF_DAT_HDR] = HDR_FTYPE_DCUP | HDR_MAJOR_V1;
+        LMIC.txCnt += 1;
+    }
+    LMIC.frame[end] = LMIC.pendTxPort;
+    os_copyMem(LMIC.frame+end+1, LMIC.pendTxData, dlen);
+    aes_cipher(LMIC.pendTxPort==0 ? LMIC.nwkKey : LMIC.artKey,
+           LMIC.devaddr, LMIC.seqnoUp-1,
+           /*up*/0, LMIC.frame+end+1, dlen);
+    }
+    aes_appendMic(LMIC.nwkKey, LMIC.devaddr, LMIC.seqnoUp-1, /*up*/0, LMIC.frame, flen-4);
+
+    EV(dfinfo, DEBUG, (e_.deveui  = MAIN::CDEV->getEui(),
+               e_.devaddr = LMIC.devaddr,
+               e_.seqno   = LMIC.seqnoUp-1,
+               e_.flags   = (LMIC.pendTxPort < 0 ? EV::dfinfo_t::NOPORT : EV::dfinfo_t::NOP),
+               e_.mic     = Base::lsbf4(&LMIC.frame[flen-4]),
+               e_.hdr     = LMIC.frame[LORA::OFF_DAT_HDR],
+               e_.fct     = LMIC.frame[LORA::OFF_DAT_FCT],
+               e_.port    = LMIC.pendTxPort,
+               e_.plen    = txdata ? dlen : 0,
+               e_.olen    = end-LORA::OFF_DAT_OPTS,
+               memcpy(e_.opts, LMIC.frame+LORA::OFF_DAT_OPTS, end-LORA::OFF_DAT_OPTS)));
+    LMIC.dataLen = flen;
+}
+
+
+// Callback from HAL during scan mode or when job timer expires.
+static void onBcnRx (xref2osjob_t job) {
+    // If we arrive via job timer make sure to put radio to rest.
+    os_radio(RADIO_RST);
+    os_clearCallback(&LMIC.osjob);
+    if( LMIC.dataLen == 0 ) {
+    // Nothing received - timeout
+    LMIC.opmode &= ~(OP_SCAN | OP_TRACK);
+    reportEvent(EV_SCAN_TIMEOUT);
+    return;
+    }
+    if( decodeBeacon() <= 0 ) {
+    // Something is wrong with the beacon - continue scan
+    LMIC.dataLen = 0;
+    os_radio(RADIO_RXON);
+    os_setTimedCallback(&LMIC.osjob, LMIC.bcninfo.txtime, FUNC_ADDR(onBcnRx));
+    return;
+    }
+    // Found our 1st beacon
+    // We don't have a previous beacon to calc some drift - assume
+    // an max error of 13ms = 128sec*100ppm which is roughly +/-100ppm
+    calcBcnRxWindowFromMillis(13,1);
+    LMIC.opmode &= ~OP_SCAN;          // turn SCAN off
+    LMIC.opmode |=  OP_TRACK;         // auto enable tracking
+    reportEvent(EV_BEACON_FOUND);    // can be disabled in callback
+}
+
+
+// Enable receiver to listen to incoming beacons
+// netid defines when scan stops (any or specific beacon)
+// This mode ends with events: EV_SCAN_TIMEOUT/EV_SCAN_BEACON
+// Implicitely cancels any pending TX/RX transaction.
+// Also cancels an onpoing joining procedure.
+static void startScan (void) {
+    ASSERT(LMIC.devaddr!=0 && (LMIC.opmode & OP_JOINING)==0);
+    if( (LMIC.opmode & OP_SHUTDOWN) != 0 )
+    return;
+    // Cancel onging TX/RX transaction
+    LMIC.txCnt = LMIC.dnConf = LMIC.bcninfo.flags = 0;
+    LMIC.opmode = (LMIC.opmode | OP_SCAN) & ~(OP_TXRXPEND);
+    setBcnRxParams();
+    LMIC.rxtime = LMIC.bcninfo.txtime = os_getTime() + sec2osticks(BCN_INTV_sec+1);
+    os_setTimedCallback(&LMIC.osjob, LMIC.rxtime, FUNC_ADDR(onBcnRx));
+    os_radio(RADIO_RXON);
+}
+
+
+bit_t LMIC_enableTracking (u1_t tryBcnInfo) {
+    if( (LMIC.opmode & (OP_SCAN|OP_TRACK|OP_SHUTDOWN)) != 0 )
+    return 0;  // already in progress or failed to enable
+    // If BCN info requested from NWK then app has to take are
+    // of sending data up so that MCMD_BCNI_REQ can be attached.
+    if( (LMIC.bcninfoTries = tryBcnInfo) == 0 )
+    startScan();
+    return 1;  // enabled
+}
+
+
+void LMIC_disableTracking (void) {
+    LMIC.opmode &= ~(OP_SCAN|OP_TRACK);
+    LMIC.bcninfoTries = 0;
+    engineUpdate();
+}
+
+
+// ================================================================================
+//
+// Join stuff
+//
+// ================================================================================
+
+static void buildJoinRequest (u1_t ftype) {
+    // Do not use pendTxData since we might have a pending
+    // user level frame in there. Use RX holding area instead.
+    xref2u1_t d = LMIC.frame;
+    d[OFF_JR_HDR] = ftype;
+    os_getArtEui(d + OFF_JR_ARTEUI);
+    os_getDevEui(d + OFF_JR_DEVEUI);
+    os_wlsbf2(d + OFF_JR_DEVNONCE, LMIC.devNonce);
+    aes_appendMic0(d, OFF_JR_MIC);
+
+    EV(joininfo,INFO,(e_.deveui  = MAIN::CDEV->getEui(),
+              e_.arteui  = MAIN::CDEV->getArtEui(),
+              e_.nonce   = LMIC.devNonce,
+              e_.oldaddr = LMIC.devaddr,
+              e_.mic     = Base::lsbf4(&d[LORA::OFF_JR_MIC]),
+              e_.flags   = ((LMIC.opmode & OP_REJOIN) != 0
+                    ? EV::joininfo_t::REJOIN_REQUEST
+                    : EV::joininfo_t::REQUEST)));
+    LMIC.dataLen = LEN_JR;
+    LMIC.devNonce++;
+    DO_DEVDB(updateDevNonce, LMIC.devNonce);
+}
+
+static void startJoining (xref2osjob_t osjob) {
+    reportEvent(EV_JOINING);
+}
+
+// Start join procedure if not already joined.
+bit_t LMIC_startJoining (void) {
+    if( LMIC.devaddr == 0 ) {
+    // There should be no TX/RX going on
+    ASSERT((LMIC.opmode & (OP_POLL|OP_TXRXPEND)) == 0);
+    // Cancel scanning
+    LMIC.opmode &= ~(OP_SCAN|OP_REJOIN|OP_LINKDEAD|OP_NEXTCHNL);
+    // Setup state
+    LMIC.rejoinCnt = LMIC.txCnt = 0;
+    initJoinLoop();
+    LMIC.opmode |= OP_OTA|OP_JOINING;
+    // reportEvent will call engineUpdate which then starts sending JOIN REQUESTS
+    os_setCallback(&LMIC.osjob, FUNC_ADDR(startJoining));
+    return 1;
+    }
+    return 0;
+}
+
+
+// ================================================================================
+//
+//
+//
+// ================================================================================
+
+static void processPingRx (xref2osjob_t osjob) {
+    if( LMIC.dataLen != 0 ) {
+    LMIC.txrxFlags = TXRX_PING;
+    if( decodeFrame() ) {
+        reportEvent(EV_RXCOMPLETE);
+        return;
+    }
+    }
+    // Pick next ping slot
+    engineUpdate();
+}
+
+
+static bit_t processDnData (void) {
+    ASSERT((LMIC.opmode & OP_TXRXPEND)!=0);
+
+    if( LMIC.dataLen == 0 ) {
+      norx:
+    if( LMIC.txCnt != 0 ) {
+        if( LMIC.txCnt <= TXCONF_ATTEMPTS ) {
+        // Schedule another retransmission
+        txDelay(LMIC.rxtime, RETRY_PERIOD_secs);
+        LMIC.opmode &= ~OP_TXRXPEND;
+        engineUpdate();
+        return 1;
+        }
+        LMIC.txrxFlags = TXRX_NACK | TXRX_NOPORT;
+    } else {
+        // Nothing received - implies no port
+        LMIC.txrxFlags = TXRX_NOPORT;
+    }
+    LMIC.adrAckReq += 1;
+    LMIC.dataBeg = LMIC.dataLen = 0;
+      txcomplete:
+    LMIC.opmode &= ~(OP_TXDATA|OP_TXRXPEND);
+    if( (LMIC.txrxFlags & (TXRX_DNW1|TXRX_DNW2|TXRX_PING)) != 0  &&  (LMIC.opmode & OP_LINKDEAD) != 0 ) {
+        LMIC.opmode &= ~OP_LINKDEAD;
+        reportEvent(EV_LINK_ALIVE);
+    }
+    reportEvent(EV_TXCOMPLETE);
+    // If we haven't heard from NWK in a while although we asked for a sign
+    // assume link is dead - notify application and keep going
+    if( LMIC.adrAckReq > LINK_CHECK_DEAD ) {
+        // We haven't heard from NWK for some time although
+        // We asked for a response for some time - assume we're disconnected. Lower DR one notch.
+        EV(devCond, ERR, (e_.reason = EV::devCond_t::LINK_DEAD,
+                  e_.eui    = MAIN::CDEV->getEui(),
+                  e_.info   = LMIC.adrAckReq));
+        setDrTxpow(DRCHG_NOADRACK, decDR((dr_t)LMIC.datarate), KEEP_TXPOW);
+        LMIC.adrAckReq = LINK_CHECK_CONT;
+        if( (LMIC.opmode & OP_OTA) != 0 ) {
+            LMIC.opmode |= OP_REJOIN|OP_LINKDEAD;
+        }
+        else {
+            LMIC.opmode |= OP_LINKDEAD;
+        }
+        reportEvent(EV_LINK_DEAD);
+    }
+    // If this falls to zero the NWK did not answer our MCMD_BCNI_REQ commands - try full scan
+    if( LMIC.bcninfoTries > 0 ) {
+        if( (LMIC.opmode & OP_TRACK) != 0 ) {
+        reportEvent(EV_BEACON_FOUND);
+        LMIC.bcninfoTries = 0;
+        }
+        else if( --LMIC.bcninfoTries == 0 ) {
+        startScan();   // NWK did not answer - try scan
+        }
+    }
+    return 1;
+    }
+    if( !decodeFrame() ) {
+    if( (LMIC.txrxFlags & TXRX_DNW1) != 0 )
+        return 0;
+    goto norx;
+    }
+    // If we received a frame reset counter
+    LMIC.adrAckReq = LINK_CHECK_INIT;
+    LMIC.rejoinCnt = 0;
+    goto txcomplete;
+}
+
+
+static void processBeacon (xref2osjob_t osjob) {
+    ostime_t lasttx = LMIC.bcninfo.txtime;   // save here - decodeBeacon might overwrite
+    u1_t flags = LMIC.bcninfo.flags;
+    ev_t ev;
+
+    if( LMIC.dataLen != 0 && decodeBeacon() >= 1 ) {
+    ev = EV_BEACON_TRACKED;
+    if( (flags & (BCN_PARTIAL|BCN_FULL)) == 0 ) {
+        // We don't have a previous beacon to calc some drift - assume
+        // an max error of 13ms = 128sec*100ppm which is roughly +/-100ppm
+        calcBcnRxWindowFromMillis(13,0);
+        goto rev;
+    }
+    // We have a previous BEACON to calculate some drift
+    s2_t drift = BCN_INTV_osticks - (LMIC.bcninfo.txtime - lasttx);
+    if( LMIC.missedBcns > 0 ) {
+        drift = LMIC.drift + (drift - LMIC.drift) / (LMIC.missedBcns+1);
+    }
+    if( (LMIC.bcninfo.flags & BCN_NODRIFT) == 0 ) {
+        s2_t diff = LMIC.drift - drift;
+        if( diff < 0 ) diff = -diff;
+        LMIC.lastDriftDiff = diff;
+        if( LMIC.maxDriftDiff < diff )
+        LMIC.maxDriftDiff = diff;
+        LMIC.bcninfo.flags &= ~BCN_NODDIFF;
+    }
+    LMIC.drift = drift;
+    LMIC.missedBcns = LMIC.rejoinCnt = 0;
+    LMIC.bcninfo.flags &= ~BCN_NODRIFT;
+    EV(devCond,INFO,(e_.reason = EV::devCond_t::CLOCK_DRIFT,
+             e_.info   = drift,
+             e_.info2  = /*occasion BEACON*/0));
+    ASSERT((LMIC.bcninfo.flags & (BCN_PARTIAL|BCN_FULL)) != 0);
+    } else {
+    ev = EV_BEACON_MISSED;
+    LMIC.bcninfo.txtime += BCN_INTV_osticks - LMIC.drift;
+    LMIC.bcninfo.time   += BCN_INTV_sec;
+    LMIC.missedBcns++;
+    // Delay any possible TX after surmised beacon - it's there although we missed it
+    txDelay(LMIC.bcninfo.txtime + BCN_RESERVE_osticks, 4);
+    if( (LMIC.opmode & OP_OTA) != 0 ) {
+    if( LMIC.missedBcns > MAX_MISSED_BCNS )
+        LMIC.opmode |= OP_REJOIN;  // try if we can roam to another network
+    }
+    if( LMIC.bcnRxsyms > MAX_RXSYMS ) {
+        LMIC.opmode &= ~(OP_TRACK|OP_PINGABLE|OP_PINGINI|OP_REJOIN);
+        reportEvent(EV_LOST_TSYNC);
+        return;
+    }
+    }
+    LMIC.bcnRxtime = LMIC.bcninfo.txtime + BCN_INTV_osticks - calcRxWindow(0,DR_BCN);
+    LMIC.bcnRxsyms = LMIC.rxsyms;    
+  rev:
+    if( (LMIC.opmode & OP_PINGINI) != 0 )
+    rxschedInit(&LMIC.ping);  // note: reuses LMIC.frame buffer!
+    reportEvent(ev);
+}
+
+
+static void startRxBcn (xref2osjob_t osjob) {
+    LMIC.osjob.func = FUNC_ADDR(processBeacon);
+    os_radio(RADIO_RX);
+}
+
+
+static void startRxPing (xref2osjob_t osjob) {
+    LMIC.osjob.func = FUNC_ADDR(processPingRx);
+    os_radio(RADIO_RX);
+}
+
+
+// Decide what to do next for the MAC layer of a device
+static void engineUpdate (void) {
+    // Check for ongoing state: scan or TX/RX transaction
+    if( (LMIC.opmode & (OP_SCAN|OP_TXRXPEND|OP_SHUTDOWN)) != 0 ) 
+    return;
+
+    if( LMIC.devaddr == 0 && (LMIC.opmode & OP_JOINING) == 0 ) {
+    LMIC_startJoining();
+    return;
+    }
+
+    ostime_t now    = os_getTime();
+    ostime_t rxtime = 0;
+    ostime_t txbeg  = 0;
+
+    if( (LMIC.opmode & OP_TRACK) != 0 ) {
+    // We are tracking a beacon
+    ASSERT( now + RX_RAMPUP - LMIC.bcnRxtime <= 0 );
+    rxtime = LMIC.bcnRxtime - RX_RAMPUP;
+    }
+
+    if( (LMIC.opmode & (OP_JOINING|OP_REJOIN|OP_TXDATA|OP_POLL)) != 0 ) {
+    // Need to TX some data...
+    // Assuming txChnl points to channel which first becomes available again.
+    bit_t jacc = ((LMIC.opmode & (OP_JOINING|OP_REJOIN)) != 0 ? 1 : 0);
+    // Find next suitable channel and return availability time
+    if( (LMIC.opmode & OP_NEXTCHNL) != 0 ) {
+        txbeg = LMIC.txend = nextTx(now);
+        LMIC.opmode &= ~OP_NEXTCHNL;
+    } else {
+        txbeg = LMIC.txend;
+    }
+    // Delayed TX or waiting for duty cycle?
+    if( (LMIC.globalDutyRate != 0 || (LMIC.opmode & OP_RNDTX) != 0)  &&  (txbeg - LMIC.globalDutyAvail) < 0 )
+        txbeg = LMIC.globalDutyAvail;
+    // If we're tracking a beacon...
+    // then make sure TX-RX transaction is complete before beacon
+    if( (LMIC.opmode & OP_TRACK) != 0 &&
+        txbeg + (jacc ? JOIN_GUARD_osticks : TXRX_GUARD_osticks) - rxtime > 0 ) {
+        // Not enough time to complete TX-RX before beacon - postpone after beacon.
+        // In order to avoid clustering of postponed TX right after beacon randomize start!
+        txDelay(rxtime + BCN_RESERVE_osticks, 16);
+        txbeg = 0;
+        goto checkrx;
+    }
+    // Earliest possible time vs overhead to setup radio
+    if( txbeg - (now + TX_RAMPUP) < 0 ) {
+        // We could send right now!
+        dr_t txdr = (dr_t)LMIC.datarate;
+        if( jacc ) {
+        u1_t ftype;
+        if( (LMIC.opmode & OP_REJOIN) != 0 ) {
+            txdr = lowerDR(txdr, LMIC.rejoinCnt);
+            ftype = HDR_FTYPE_REJOIN;
+        } else {
+            ftype = HDR_FTYPE_JREQ;
+        }
+        buildJoinRequest(ftype);
+        LMIC.osjob.func = FUNC_ADDR(jreqDone);
+        } else {
+        if( LMIC.seqnoUp == 0xFFFFFFFF ) {
+            // Roll over of up seq counter
+            EV(specCond, ERR, (e_.reason = EV::specCond_t::UPSEQNO_ROLL_OVER,
+                       e_.eui    = MAIN::CDEV->getEui()));
+            // Rerun join procedure - start with current datarate
+            LMIC.devaddr = 0;
+            LMIC_startJoining();
+            reportEvent(EV_RESET);
+            return;
+        }
+        buildDataFrame();
+        // NOTE: a channel decision for LMIC.txChnl above will never be rendered invalid
+        // by chosing a slower datarate (it could be invalided ONLY by a faster datarate).
+        txdr = lowerDR(txdr, DRADJUST[LMIC.txCnt]);
+        LMIC.osjob.func = FUNC_ADDR(updataDone);
+        }
+        LMIC.rps    = setCr(updr2rps(txdr), (cr_t)LMIC.errcr);
+        LMIC.rxsyms = txdr;  // carry TX datarate (can be != LMIC.datarate) over to txDone/setupRx1
+        LMIC.opmode = (LMIC.opmode & ~(OP_POLL|OP_RNDTX)) | OP_TXRXPEND | OP_NEXTCHNL;
+        updateTx(txbeg);
+        os_radio(RADIO_TX);
+        return;
+    }
+    // Cannot yet TX
+    if( (LMIC.opmode & OP_TRACK) == 0 )
+        goto txdelay; // We don't track the beacon - nothing else to do - so wait for the time to TX
+    // Consider RX tasks
+    if( txbeg == 0 ) // zero indicates no TX pending
+        txbeg += 1;  // TX delayed by one tick (insignificant amount of time)
+    } else {
+    // No TX pending - no scheduled RX
+    if( (LMIC.opmode & OP_TRACK) == 0 )
+        return;
+    }
+
+    // Are we pingable?
+  checkrx:
+    if( (LMIC.opmode & OP_PINGINI) != 0 ) {
+    // One more RX slot in this beacon period?
+    if( rxschedNext(&LMIC.ping, now+RX_RAMPUP) ) {
+        if( txbeg != 0  &&  (txbeg - LMIC.ping.rxtime) < 0 )
+        goto txdelay;
+        LMIC.rxsyms  = LMIC.ping.rxsyms;
+        LMIC.rxtime  = LMIC.ping.rxtime;
+        LMIC.freq    = LMIC.ping.freq;
+        LMIC.rps     = dndr2rps(LMIC.ping.dr);
+        LMIC.dataLen = 0;
+        ASSERT(LMIC.rxtime - now+RX_RAMPUP >= 0 );
+        os_setTimedCallback(&LMIC.osjob, LMIC.rxtime - RX_RAMPUP, FUNC_ADDR(startRxPing));
+        return;
+    }
+    // no - just wait for the beacon
+    }
+
+    if( txbeg != 0  &&  (txbeg - rxtime) < 0 )
+    goto txdelay;
+
+    setBcnRxParams();
+    LMIC.rxsyms = LMIC.bcnRxsyms;
+    LMIC.rxtime = LMIC.bcnRxtime;
+    if( now - rxtime >= 0 ) {
+    LMIC.osjob.func = FUNC_ADDR(processBeacon);
+    os_radio(RADIO_RX);
+    return;
+    }
+    os_setTimedCallback(&LMIC.osjob, rxtime, FUNC_ADDR(startRxBcn));
+    return;
+
+  txdelay:
+    EV(devCond, INFO, (e_.reason = EV::devCond_t::TX_DELAY,
+               e_.eui    = MAIN::CDEV->getEui(),
+               e_.info   = osticks2ms(txbeg-now),
+               e_.info2  = LMIC.seqnoUp-1));
+    os_setTimedCallback(&LMIC.osjob, txbeg-TX_RAMPUP, FUNC_ADDR(runEngineUpdate));
+}
+
+
+void LMIC_setAdrMode (bit_t enabled) {
+    LMIC.adrEnabled = enabled ? FCT_ADREN : 0;
+}
+
+
+//  Should we have/need an ext. API like this?
+void LMIC_setDrTxpow (dr_t dr, s1_t txpow) {
+    setDrTxpow(DRCHG_SET, dr, txpow);
+}
+
+
+void LMIC_shutdown (void) {
+    os_clearCallback(&LMIC.osjob);
+    os_radio(RADIO_RST);
+    LMIC.opmode |= OP_SHUTDOWN;
+}
+
+
+void LMIC_reset (void) {
+    EV(devCond, INFO, (e_.reason = EV::devCond_t::LMIC_EV,
+               e_.eui    = MAIN::CDEV->getEui(),
+               e_.info   = EV_RESET));
+    os_radio(RADIO_RST);
+    os_clearCallback(&LMIC.osjob);
+
+    os_clearMem((xref2u1_t)&LMIC,SIZEOFEXPR(LMIC));
+    LMIC.devaddr     = 0;
+    LMIC.devNonce    = os_getRndU2();
+    LMIC.opmode      = OP_NONE;
+    LMIC.errcr       = CR_4_5;
+    LMIC.adrEnabled  = FCT_ADREN;
+    LMIC.dn2Dr       = DR_DNW2;   // we need this for 2ns DN window of join accept
+    LMIC.dn2Freq     = FREQ_DNW2; // ditto
+#if CFG_us915
+    initDefaultChannels();
+#endif
+}
+
+
+void LMIC_init (void) {
+    LMIC.opmode = OP_SHUTDOWN;
+}
+
+
+void LMIC_clrTxData (void) {
+    LMIC.opmode &= ~(OP_TXDATA|OP_TXRXPEND|OP_POLL);
+    LMIC.pendTxLen = 0;
+    if( (LMIC.opmode & (OP_JOINING|OP_SCAN)) != 0 ) // do not interfere with JOINING
+    return;
+    os_clearCallback(&LMIC.osjob);
+    os_radio(RADIO_RST);
+    engineUpdate();
+}
+
+
+void LMIC_setTxData (void) {
+    LMIC.opmode |= OP_TXDATA;
+    if( (LMIC.opmode & OP_JOINING) == 0 )
+    LMIC.txCnt = 0;             // cancel any ongoing TX/RX retries
+    engineUpdate();
+}
+
+
+//
+int LMIC_setTxData2 (u1_t port, xref2u1_t data, u1_t dlen, u1_t confirmed) {
+    if( dlen > SIZEOFEXPR(LMIC.pendTxData) )
+    return -2;
+    if( data != (xref2u1_t)0 )
+    os_copyMem(LMIC.pendTxData, data, dlen);
+    LMIC.pendTxConf = confirmed;
+    LMIC.pendTxPort = port;
+    LMIC.pendTxLen  = dlen;
+    LMIC_setTxData();
+    return 0;
+}
+
+
+// Send a payload-less message to signal device is alive
+void LMIC_sendAlive (void) {
+    LMIC.opmode |= OP_POLL;
+    engineUpdate();
+}
+
+
+// Check if other networks are around.
+void LMIC_tryRejoin (void) {
+    LMIC.opmode |= OP_REJOIN;
+    engineUpdate();
+}
+
+void LMIC_startABP(u4_t netid, devaddr_t devaddr, u1_t* nwkKey, u1_t* artKey)
+{
+    LMIC.netid = netid;
+    LMIC.devaddr = devaddr;
+    memcpy(LMIC.nwkKey, nwkKey, 16);
+    memcpy(LMIC.artKey, artKey, 16);
+    
+#if CFG_eu868
+    initDefaultChannels(0);
+#endif
+
+    LMIC.opmode &= ~(OP_JOINING|OP_TRACK|OP_REJOIN|OP_TXRXPEND|OP_PINGINI) | OP_NEXTCHNL;
+    stateJustJoined();
+    //engineUpdate();
+    reportEvent(EV_JOINED);
+}