Teensy 3.2 + Snooze + LoRaWAN LMIC stack problem

Hii guys,

I’m using an Teensy 3.2 with an SX1276 LoRa chip. For the LoRaWAN stack I’m using the LMIC v 1.5 library.

Because it’s battery powered I’m using duffs Snooze library in combination with an 32kHz crystal + 3V battery to put the Teensy in hibernate mode while not sending anything. Once every x minutes it wakes up, takes measurements and sends it’s data to The Things Network.

The code works perfectly without putting it into hibernate or sleep mode, but when I insert the code for the hibernate it start acting weird. I get huge delays in sending the data. I think the millis() counter is out of sync with the LMIC stack, had the same problem using Arduino but fixed it with this piece of code:

//Give the AVR back the slept time back (simple version)
cli();
timer0_overflow_count += 8 * 64 * clockCyclesPerMicrosecond(); //give back 60 seconds of sleep
sei();
os_getTime(); //VERY IMPORTANT after sleep to update os_time and not cause txbeg and os_time out of sync which causes send delays with the RFM95 on and eating power

Now I have no idea how to do this with the Teensy. Below is my simplified code of my Teensy + Snooze + LMIC without sensors (not relevant for my question):

Anyone got experience with the Snooze + LMIC library? Thanks in advance

CLICK to see code

> #include <lmic.h>
> #include <hal/hal.h>
> #include <SPI.h>
> #include <Snooze.h>
> #include <i2c_t3.h>
> 
> // LoRaWAN NwkSKey, network session key
> // This is the default Semtech key, which is used by the early prototype TTN
> // network.
> static const PROGMEM u1_t NWKSKEY[16] = { MyNWKSKEY };
> 
> // LoRaWAN AppSKey, application session key
> // This is the default Semtech key, which is used by the early prototype TTN
> // network.
> static const u1_t PROGMEM APPSKEY[16] = { MyAPPSKEY };
> 
> // LoRaWAN end-device address (DevAddr)
> static const u4_t DEVADDR = myDEVADDR ; // <-- Change this address for every node!
> 
> // These callbacks are only used in over-the-air activation, so they are
> // left empty here (we cannot leave them out completely unless
> // DISABLE_JOIN is set in config.h, otherwise the linker will complain).
> void os_getArtEui (u1_t* buf) { }
> void os_getDevEui (u1_t* buf) { }
> void os_getDevKey (u1_t* buf) { }
> 
> static osjob_t sendjob;
> 
> // Schedule TX every this many seconds (might become longer due to duty
> // cycle limitations).
> const unsigned TX_INTERVAL = 60;
> 
> // Pin mapping
> const lmic_pinmap lmic_pins = {
>   .nss = 10,
>   .rxtx = LMIC_UNUSED_PIN,
>   .rst = 4,
>   .dio = {2, 3, LMIC_UNUSED_PIN},
> };
> 
> int who;
> 
> SnoozeAlarm alarm;
> SnoozeBlock config_teensy32(alarm);
> 
> 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"));
>       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;
>     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"));
>         WinterSlaap();
>       }
>       else {
>         WinterSlaap();
>       }
>       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 {
>     byte payload [1];
>     payload [0] = 1;
>     LMIC_setTxData2(1, payload, sizeof(payload), 0);
>     Serial.println(F("Packet queued"));
>   }
>   // Next TX is scheduled after TX_COMPLETE event.
> }
> 
> void setup() {
>   Serial.begin(115200);
>   Serial.println(F("Starting"));
> 
>   pinMode (21, OUTPUT);
>   digitalWrite (21, HIGH);
> 
>   //alarm.setRtcTimer(0, 0, 20);// Uren, minuten, secondes
> 
>   // LMIC init
>   os_init();
>   // Reset the MAC state. Session and pending data transfers will be discarded.
>   LMIC_reset();
>   
>   os_setTimedCallback(&sendjob, os_getTime() + ms2osticks(10), do_send);
>   // Set static session parameters. Instead of dynamically establishing a session
>   // by joining the network, precomputed session parameters are be provided.
> #ifdef PROGMEM
>   // On AVR, these values are stored in flash and only copied to RAM
>   // once. Copy them to a temporary buffer here, LMIC_setSession will
>   // copy them into a buffer of its own again.
>   uint8_t appskey[sizeof(APPSKEY)];
>   uint8_t nwkskey[sizeof(NWKSKEY)];
>   memcpy_P(appskey, APPSKEY, sizeof(APPSKEY));
>   memcpy_P(nwkskey, NWKSKEY, sizeof(NWKSKEY));
>   LMIC_setSession (0x1, DEVADDR, nwkskey, appskey);
> #else
>   // If not running an AVR with PROGMEM, just use the arrays directly
>   LMIC_setSession (0x1, DEVADDR, NWKSKEY, APPSKEY);
> #endif
> 
> #if defined(CFG_eu868)
>   // Set up the channels used by the Things Network, which corresponds
>   // to the defaults of most gateways. Without this, only three base
>   // channels from the LoRaWAN specification are used, which certainly
>   // works, so it is good for debugging, but can overload those
>   // frequencies, so be sure to configure the full frequency range of
>   // your network here (unless your network autoconfigures them).
>   // Setting up channels should happen after LMIC_setSession, as that
>   // configures the minimal channel set.
>   // NA-US channels 0-71 are configured automatically
>   LMIC_setupChannel(0, 868100000, DR_RANGE_MAP(DR_SF12, DR_SF7),  BAND_CENTI);      // g-band
>   LMIC_setupChannel(1, 868300000, DR_RANGE_MAP(DR_SF12, DR_SF7B), BAND_CENTI);      // g-band
>   LMIC_setupChannel(2, 868500000, DR_RANGE_MAP(DR_SF12, DR_SF7),  BAND_CENTI);      // g-band
>   LMIC_setupChannel(3, 867100000, DR_RANGE_MAP(DR_SF12, DR_SF7),  BAND_CENTI);      // g-band
>   LMIC_setupChannel(4, 867300000, DR_RANGE_MAP(DR_SF12, DR_SF7),  BAND_CENTI);      // g-band
>   LMIC_setupChannel(5, 867500000, DR_RANGE_MAP(DR_SF12, DR_SF7),  BAND_CENTI);      // g-band
>   LMIC_setupChannel(6, 867700000, DR_RANGE_MAP(DR_SF12, DR_SF7),  BAND_CENTI);      // g-band
>   LMIC_setupChannel(7, 867900000, DR_RANGE_MAP(DR_SF12, DR_SF7),  BAND_CENTI);      // g-band
>   LMIC_setupChannel(8, 868800000, DR_RANGE_MAP(DR_FSK,  DR_FSK),  BAND_MILLI);      // g2-band
>   // TTN defines an additional channel at 869.525Mhz using SF9 for class B
>   // devices' ping slots. LMIC does not have an easy way to define set this
>   // frequency and support for class B is spotty and untested, so this
>   // frequency is not configured here.
> #elif defined(CFG_us915)
>   // NA-US channels 0-71 are configured automatically
>   // but only one group of 8 should (a subband) should be active
>   // TTN recommends the second sub band, 1 in a zero based count.
>   // https://github.com/TheThingsNetwork/gateway-conf/blob/master/US-global_conf.json
>   LMIC_selectSubBand(1);
> #endif
> 
>   // Disable link check validation
>   LMIC_setLinkCheckMode(0);
> 
>   // TTN uses SF9 for its RX2 window.
>   LMIC.dn2Dr = DR_SF9;
> 
>   // Set data rate and transmit power for uplink (note: txpow seems to be ignored by the library)
>   LMIC_setDrTxpow(DR_SF7, 14);
> 
>   // Start job
>   do_send(&sendjob);
> }
> 
> void loop() {
>   os_runloop_once();
>   who = Snooze.hibernate( config_teensy32 );
>   digitalWrite (21, HIGH);
>   if (who == 35) {
>     digitalWrite (21, HIGH);
>     Serial.begin(115200);
>     Serial.println ("Uit slaap!");
>     delay(5000);
>     
>     //Give the AVR back the slept time back (simple version)
>     //cli();
>     //timer0_overflow_count += 8 * 64 * clockCyclesPerMicrosecond(); //give back seconds of sleep
>     //sei();
> 
>     os_getTime();   //VERY IMPORTANT after sleep to update os_time and not cause txbeg and os_time out of sync which causes send delays with the RFM95 on and eating power
>     //Do here whatever needs to be done after each of the sleepcycle (e.g. check for a condition to break for send or take measurements for mean values etc.)
> 
>     os_setTimedCallback(&sendjob, os_getTime() + ms2osticks(10), do_send);  //do a send
> 
>     Serial.println(F("go to sleep ... "));
>     Serial.println ("delay van 5sec");
>     delay (5000);
>   }
> }
> 
> void WinterSlaap (){
>   digitalWrite (21, LOW);
>   Serial.flush();
>   Snooze.hibernate( alarm );  
> }