Adding LowPower to LMiC 4.0 OTAA example for ProMini - TTN v3

Hi Everyone,

I’m trying to add LowPower sleep mode to my Arduino Pro Mini LoRa node. I’ve taken the MCCI Catena LMiC v4.0 OTAA ttn example sketch and followed tutorials to add the sleep mode, as well as BME280 and DS18B20 sensors just to send some payload. I have another node working fine on the TTN v3 network (OTAA) with the same code, just without sleep.

When I try to add LowPower, I have problems joining the network. I understand that LowPower mode affects the LMiC timing and wanted to know what the best current solution is for this, and if the issue has been resolved?

I followed the tutorials below but they are based on the ABP joining method, so not sure if its being implemented correctly for OTAA. Does anyone have an example of successfully running LowPower using OTAA on TTN v3 with LMiC 4.0 ?

Here is my code (sleep mode code is at the bottom in void loop):

/*******************************************************************************
 * Copyright (c) 2015 Thomas Telkamp and Matthijs Kooijman
 * Copyright (c) 2018 Terry Moore, MCCI
 *
 * 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
 * arduino-lmic/project_config/lmic_project_config.h or from your BOARDS.txt.
 *
 *******************************************************************************/

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

#include <DS18B20.h>
#include "SparkFunBME280.h"
#include "LowPower.h"

#define SLEEP
bool next = false;

// For normal use, we require that you edit the sketch to replace FILLMEIN
// with values assigned by the TTN console. However, for regression tests,
// we want to be able to compile these scripts. The regression tests define
// COMPILE_REGRESSION_TEST, and in that case we define FILLMEIN to a non-
// working but innocuous value.
//
#ifdef COMPILE_REGRESSION_TEST
# define FILLMEIN 0
#else
# warning "You must replace the values marked FILLMEIN with real values from the TTN control panel!"
# define FILLMEIN (#dont edit this, edit the lines that use FILLMEIN)
#endif

// 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]={ --};
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]={ -- };
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 ttnctl can be copied as-is.
static const u1_t PROGMEM APPKEY[16]={ -- };
void os_getDevKey (u1_t* buf) {  memcpy_P(buf, APPKEY, 16);}

static osjob_t sendjob;
int fPort = 1;               

// Schedule TX every this many seconds (might become longer due to duty
// cycle limitations).
const unsigned TX_INTERVAL = 120;

// Pin mapping
const lmic_pinmap lmic_pins = {
  .nss = 10,
  .rxtx = LMIC_UNUSED_PIN,
  .rst = 9,
  .dio = {2, 5, LMIC_UNUSED_PIN},
};

void printHex2(unsigned v) {
    v &= 0xff;
    if (v < 16)
        Serial.print('0');
    Serial.print(v, HEX);
}


// Create DS18S20 object, on digital pin 8
 DS18B20 ds1(8);

 // Create BME280 object, using I2C
BME280 mySensorA;

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("AppSKey: ");
              for (size_t i=0; i<sizeof(artKey); ++i) {
                if (i != 0)
                  Serial.print("-");
                printHex2(artKey[i]);
              }
              Serial.println("");
              Serial.print("NwkSKey: ");
              for (size_t i=0; i<sizeof(nwkKey); ++i) {
                if (i != 0)
                  Serial.print("-");
                printHex2(nwkKey[i]);
              }
              Serial.println();
            }
            // Disable link check validation (automatically enabled
            // during join, but because slow data rates change max TX
        // size, we don't use it in this example.
            LMIC_setLinkCheckMode(0);
            break;
        /*
        || This event is defined but not used in the code. No
        || point in wasting codespace on it.
        ||
        || 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;
        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.print(F("Received "));
              Serial.print(LMIC.dataLen);
              Serial.println(F(" bytes of payload"));
            }                    
            // Schedule next transmission
            
            // os_setTimedCallback(&sendjob, os_getTime()+sec2osticks(TX_INTERVAL), do_send);  // disabled for merge
            
            #ifndef SLEEP
                        os_setTimedCallback(&sendjob, os_getTime()+sec2osticks(TX_INTERVAL), do_send);
            #else
                        next = true;
            #endif           

            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;
        /*
        || This event is defined but not used in the code. No
        || point in wasting codespace on it.
        ||
        || case EV_SCAN_FOUND:
        ||    Serial.println(F("EV_SCAN_FOUND"));
        ||    break;
        */
        case EV_TXSTART:
            Serial.println(F("EV_TXSTART"));
            break;
        case EV_TXCANCELED:
            Serial.println(F("EV_TXCANCELED"));
            break;
        case EV_RXSTART:
            /* do not print anything -- it wrecks timing */
            break;
        case EV_JOIN_TXCOMPLETE:
            Serial.println(F("EV_JOIN_TXCOMPLETE: no JoinAccept"));
            break;
        
        default:
            Serial.print(F("Unknown event: "));
            Serial.println((unsigned) ev);
            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 {
   
    float DS18 = ds1.getTempC();
    Serial.print("DS18TempC: ");
    Serial.println(DS18);
    int16_t DS18100 = int16_t(DS18 * 100);

    float BMETemp = mySensorA.readTempC() -1;
    Serial.print("BMETemp: ");
    Serial.println(BMETemp);

    float Hum = mySensorA.readFloatHumidity();
    Serial.print("RH%: ");
    Serial.println(Hum);

    float BP = mySensorA.readFloatPressure() / 100 - 800;
    Serial.print("Pressure: ");
    Serial.println(BP);
     
      int16_t Hum100 = int16_t(Hum * 100);
      int16_t BMETemp100 = int16_t(BMETemp * 100);
      int16_t BP100 = int16_t(BP * 100);
               
        byte payload[8];
        payload[0] = highByte(DS18100);
        payload[1] = lowByte(DS18100);
        payload[2] = highByte(BMETemp100);
        payload[3] = lowByte(BMETemp100);
        payload[4] = highByte(BP100);
        payload[5] = lowByte(BP100);   
        payload[6] = highByte(Hum100);
        payload[7] = lowByte(Hum100); 

      fPort = 1;
         
        //Prepare upstream data transmission at the next possible time.
        LMIC_setTxData2(fPort, payload, sizeof(payload), 0);
//        Serial.println(F("Packet queued"));
    }
    // Next TX is scheduled after TX_COMPLETE event.
}

void setup() {
  
  //***Set up BME280***
  //commInterface can be I2C_MODE or SPI_MODE
  mySensorA.settings.commInterface = I2C_MODE;
  mySensorA.settings.I2CAddress = 0x76;
  mySensorA.settings.runMode = 1; //  1 is forced mode, 3 is Normal mode
  mySensorA.settings.tStandby = 0; //  0, 0.5ms
  mySensorA.settings.filter = 0; //  0, filter off
  //tempOverSample can be:
  //  0, skipped
  //  1 through 5, oversampling *1, *2, *4, *8, *16 respectively
  mySensorA.settings.tempOverSample = 3;
  //pressOverSample can be:
  //  0, skipped
  //  1 through 5, oversampling *1, *2, *4, *8, *16 respectively
    mySensorA.settings.pressOverSample = 3;
  //humidOverSample can be:
  //  0, skipped
  //  1 through 5, oversampling *1, *2, *4, *8, *16 respectively
  mySensorA.settings.humidOverSample = 3;
//***end BME280 Setup***
  
//    while (!Serial); // wait for Serial to be initialized
    Serial.begin(115200);
    delay(100);     // per sample code on RF_95 test
    Serial.println(F("Starting.."));
   
    delay(10);  //Make sure sensor had enough time to turn on. BME280 requires 2ms to start up.
    //Calling .begin() causes the settings to be loaded
    Serial.print("BME280: 0x");
    Serial.println(mySensorA.begin(), HEX);
       
    // LMIC init
    os_init();
    // Reset the MAC state. Session and pending data transfers will be discarded.
    LMIC_reset();

    // Use with Arduino Pro Mini ATmega328P 3.3V 8 MHz
    // Let LMIC compensate for +/- 1% clock error
    LMIC_setClockError(MAX_CLOCK_ERROR * 1 / 100); 

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

//void loop() {   
//    os_runloop_once();
//}

void loop() {

#ifndef SLEEP

  os_runloop_once();
  
#else

  if (next == false) {

    os_runloop_once();

  } else {

    int sleepcycles = TX_INTERVAL / 8;  // calculate the number of sleepcycles (8s) given the TX_INTERVAL
      Serial.print(F("Enter sleeping for "));
      Serial.print(sleepcycles);
      Serial.println(F(" cycles of 8 seconds"));
    delay(500); // give the serial print chance to complete

    for (int i=0; i<sleepcycles; i++) {
      // Enter power down state for 8 s with ADC and BOD module disabled
      LowPower.powerDown(SLEEP_8S, ADC_OFF, BOD_OFF);
      //LowPower.idle(SLEEP_8S, ADC_OFF, TIMER2_OFF, TIMER1_OFF, TIMER0_OFF, SPI_OFF, USART0_OFF, TWI_OFF);
    }
      Serial.println(F("Sleep complete"));
    next = false;
    // Start job
    do_send(&sendjob);
  } 
#endif
}