Hi everyone 
It feels like I’ve read every post in this forum about ABP and still I cannot find the answer of my problem. The code is attached below, don’t worry because of some german comments in it.
My problem
I’m transmitting the temperature value and part of the address (for identification in backend) of six DS18B20 sensors. My payload isn’t optimized and a bit too large, according to the TTN console 49 bytes. With spreading factor 7 and a interval of 12 minutes I should be inside fair use policy.
Everything works fine for 1 to 2 hours (not always the same) and then it slows down to a 70min interval. After weeks of usage it even slows down to a 3 or 4 hours interval.
Stuff I’m using
- Arduino Mega with Dragino LoRa Shield
- Latest Arduino-LMIC library from mcci-catena
- Single channel gateway: RasPi with [Dragino LoRa Hat](http://LoRa / GPS HAT Raspberry Pi - 868MHz v1.4 Dragino)
- Displaying the data on my custom website
My question
I have some guesses where my slow down comes from, but I’m far from shure where my problem comes from. Is it a…
- duty cycle limitation? But increasing Interval didn’t change anything and airtime calculator looks fine to me (even thought payload size could be optimized).
- memory leakage? It’s my first contact with C, I’m a Javascript coder
-
millis()overflow problem? So any idea how to solve?
If I reset the node everything starts working again for two hours… 
Background
- I tried to overwrite with X the privacy related stuff, I hope I didn’t remove values you wanted to see.
- The sensors get used in our farm to monitor the cherry trees. So we can try to protect them from frost in spring (yes, I’m a bit stressed
).
The code
Arduino node code
/*******************************************************************************
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 ABP (Activation-by-personalisation), where a DevAddr and
Session keys are preconfigured (unlike OTAA, where a DevEUI and
application key is configured, while the DevAddr and session keys are
assigned/generated in the over-the-air-activation procedure).
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 a DevAddr, NwkSKey and
AppSKey. Each device should have their own unique values for these
fields.
Do not forget to define the radio type correctly in
arduino-lmic/project_config/lmic_project_config.h or from your BOARDS.txt.
*******************************************************************************/
// References:
// [feather] adafruit-feather-m0-radio-with-lora-module.pdf
#include <lmic.h>
#include <hal/hal.h>
#include <SPI.h>
#include <OneWire.h>
#include <DallasTemperature.h>
// OneWire-Instanz anlegen
OneWire oneWire(24);// Die Sensoren werden mit PIN 24 verbunden
// DS18B20-Instanz anlegen
DallasTemperature ds18b20(&oneWire);
int deviceCount;
int redLED = 28;
// LoRaWAN NwkSKey, network session key
static const PROGMEM u1_t NWKSKEY[16] = { 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX };
// LoRaWAN AppSKey, application session key
static const u1_t PROGMEM APPSKEY[16] = { 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX };
// LoRaWAN end-device address (DevAddr)
// See http://thethingsnetwork.org/wiki/AddressSpace
// The library converts the address to network byte order as needed.
static const u4_t DEVADDR = 0xXXXXXXXX ; // <-- 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 arduino-lmic/project_config/lmic_project_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) { }
uint8_t mydata[] = "xyz500xyz500xyz500xyz500xyz500xyz500";
static osjob_t sendjob;
// Schedule TX every this many seconds (might become longer due to duty
// cycle limitations).
const unsigned TX_INTERVAL = 60 * 12;
// Pin mapping
// Adapted for Feather M0 per p.10 of [feather]
const lmic_pinmap lmic_pins = {
.nss = 10, // chip select on feather (rf95module) CS
.rxtx = LMIC_UNUSED_PIN,
.rst = 9, // reset pin
.dio = {2, 6, 7}, // assumes external jumpers [feather_lora_jumper]
// DIO1 is on JP1-1: is io1 - we connect to GPO6
// DIO1 is on JP5-3: is D2 - we connect to GPO5
};
double temp[6]; // 6 Temperaturfühler
char temp_buffer[6][6];
void writeTempToTempBuffer() {
// Lese von allen Temp-Sensoren und befülle das Char-Array
ds18b20.requestTemperatures();
Serial.println("Temperaturwerte: ");
// Gebe Zeit für die Messung!
delay(1000);
for (int i = 0; i < 6; i++) {
String tempString;
char tempChar[3];
String deviceString;
DeviceAddress deviceAddr;
temp[i] = -50; // Standardwert setzen
temp[i] = ds18b20.getTempCByIndex(i);
if (temp[i] == 85.0) { // Fehler beim Lesen des Sensors, erneuter Versuch
Serial.print("Lesefehler bei Sensor "); Serial.print(i); Serial.println(" . Versuche es erneut.");
temp[i] = ds18b20.getTempCByIndex(i);
}
if (temp[i] < -49 || temp[i] > 49) { // ungültige Werte
temp[i] = -50; // Standardwert setzen
}
// Standardwert setzen
if (i < deviceCount) {
ds18b20.getAddress(deviceAddr, i);
for (uint8_t ij = 0; ij < 8; ij++)
{
deviceString += String(deviceAddr[ij], HEX);
}
deviceString = deviceString.substring(4, 7);
} else {
deviceString = "yyy";
}
Serial.print("Sensor "); Serial.print(deviceString); Serial.print("(#"); Serial.print(i); Serial.print("): ");
Serial.print(temp[i]); Serial.print("°C ("); Serial.print(ds18b20.getTempCByIndex(i)); Serial.println("), ");
temp[i] = temp[i] + 50; // 50 dazurechnen, um immer positive Werte zu haben
temp[i] = temp[i] * 10; // *10, um Dezimalwert wegzumachen
// dtostrf(FLOAT,WIDTH,PRECSISION,BUFFER);
dtostrf (temp[i], 3, 0, tempChar);
// Alles ins Char-Array schreiben
(deviceString + String(tempChar)).toCharArray(temp_buffer[i], 7);
}
}
void prepareData() {
writeTempToTempBuffer();
// Das cheiben Zeugs mit dem char-Array...
int q = 0;
for (int i = 0; i < 6; i++) {
for (int j = 0; j < 6; j++) {
mydata[q] = temp_buffer[i][j];
q++;
}
}
}
void blinkRedLED (int count) {
for (int i = 0; i < count; i++) {
digitalWrite(redLED, LOW);
delay(500);
digitalWrite(redLED, HIGH);
delay(500);
}
}
void onEvent (ev_t ev) {
Serial.print(os_getTime());
Serial.print("|");
Serial.print((unsigned long)(os_getTime() / OSTICKS_PER_SEC));
Serial.print("s: ");
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;
/*
|| 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)"));
// LED blinken lassen bei Übermittlung => HIGH == aus (minusgeschaltet)
blinkRedLED(deviceCount);
if (LMIC.txrxFlags & TXRX_ACK)
Serial.println(F("Received ack"));
if (LMIC.dataLen) {
Serial.println(F("Received "));
Serial.println(LMIC.dataLen);
Serial.println(F(" bytes of payload"));
}
// Schedule next transmission
os_setTimedCallback(&sendjob, os_getTime() + sec2osticks(TX_INTERVAL), do_send);
break;
case EV_LOST_TSYNC:
Serial.println(F("EV_LOST_TSYNC"));
break;
case EV_RESET:
Serial.println(F("EV_RESET"));
break;
case EV_RXCOMPLETE:
// data received in ping slot
Serial.println(F("EV_RXCOMPLETE"));
break;
case EV_LINK_DEAD:
Serial.println(F("EV_LINK_DEAD"));
break;
case EV_LINK_ALIVE:
Serial.println(F("EV_LINK_ALIVE"));
break;
/*
|| 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_SCAN_FOUND:
Serial.println(F("EV_SCAN_FOUND"));
break;
case EV_TXCANCELED:
Serial.println(F("EV_TXCANCELED"));
break;
case EV_RXSTART:
Serial.println(F("EV_RXSTART"));
break;
case EV_JOIN_TXCOMPLETE:
Serial.println(F("EV_JOIN_TXCOMPLETE"));
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 {
// Präpariere Daten für das senden
prepareData();
delay(500);
// Prepare upstream data transmission at the next possible time.
LMIC_setTxData2(1, mydata, sizeof(mydata) - 1, 0);
Serial.println(F("Packet queued"));
// Show TX channel (channel numbers are local to LMIC)
Serial.print("Send, txCnhl: ");
Serial.println(LMIC.txChnl);
// Zeige länge und Daten
Serial.print("Length: ");
Serial.print(sizeof(mydata));
Serial.print("; Data: '");
for (int q = 0; q < sizeof(mydata); q++) {
Serial.print(char(mydata[q]));
}
Serial.print("'");
Serial.println();
}
// Next TX is scheduled after TX_COMPLETE event.
}
void setup() {
// pinMode(13, OUTPUT);
pinMode(redLED, OUTPUT);
digitalWrite(redLED, HIGH); // HIGH == LED ausgeschaltet
while (!Serial); // wait for Serial to be initialized
Serial.begin(115200);
delay(100); // per sample code on RF_95 test
Serial.println(F("Starting"));
// DS18B20-Instanz starten
ds18b20.begin();
// Genauigkeit festlegen
// Mode Resol Reading time
// 9 0.5°C 93.75 ms
// 10 0.25°C 187.5 ms
// 11 0.125°C 375 ms
// 12 0.0625°C 750 ms
// Bleibt im EEPROM gespeichert, muss deshalb
// nur bei neuem Sensor ausgeführt werden
//ds18b20.setResolution(11); //TODO: remove
// Lese von allen Temp-Sensoren und befülle das Char-Array
ds18b20.requestTemperatures();
// Gebe Zeit für die Messung!
delay(1000);
// Zähle die Geräte auf dem Bus
deviceCount = ds18b20.getDS18Count();
Serial.print(deviceCount); Serial.println(" Sensor(en) gefunden.");
#ifdef VCC_ENABLE
// For Pinoccio Scout boards
pinMode(VCC_ENABLE, OUTPUT);
digitalWrite(VCC_ENABLE, HIGH);
delay(1000);
#endif
// LMIC init
os_init();
// Reset the MAC state. Session and pending data transfers will be discarded.
LMIC_reset();
LMIC_setClockError(MAX_CLOCK_ERROR * 1 / 100); //Relax RX timing window
// Disable link check validation
LMIC_setLinkCheckMode(0);
// 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 (0x13, DEVADDR, nwkskey, appskey);
#else
// If not running an AVR with PROGMEM, just use the arrays directly
LMIC_setSession (0x13, 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.
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 all channels except 0, because I'm using a single channel gateway
for (int channel = 1; channel < 9; ++channel) {
LMIC_disableChannel(channel);
}
// TTN uses SF9 for its RX2 window.
LMIC.dn2Dr = DR_SF9;
// Set data rate and transmit power for uplink
LMIC_setDrTxpow(DR_SF7, 14);
// Start job
do_send(&sendjob);
}
void loop() {
unsigned long now;
now = millis();
if ((now & 512) != 0) {
digitalWrite(13, HIGH);
}
else {
digitalWrite(13, LOW);
}
os_runloop_once();
}
lmic_project_config.h file
// project-specific definitions
#define CFG_eu868 1
//#define CFG_us915 1
//#define CFG_au921 1
//#define CFG_as923 1
// #define LMIC_COUNTRY_CODE LMIC_COUNTRY_CODE_JP /* for as923-JP */
//#define CFG_in866 1
#define CFG_sx1276_radio 1
//#define LMIC_USE_INTERRUPTS
#define DISABLE_JOIN
#define DISABLE_PING
#define DISABLE_BEACONS
Output of the TTN console
{
"gw_id": "eui-XXXXXXXXXXXXXXXX",
"payload": "QNwRASaAAAABX1LSvPH1P2O+1PT9IZgaB2Hy/68aBo05c9EbeDf412mUUgbEHnj7gQ==",
"lora": {
"spreading_factor": 7,
"bandwidth": 125,
"air_time": 97536000
},
"coding_rate": "4/5",
"timestamp": "2019-03-27T16:51:29.043Z",
"rssi": -67,
"snr": 9,
"dev_addr": "XXXXXXXX",
"frequency": 868100000
}
But shure, if that’s the problem it has to be done.
. So I was totaly lazy in terms of power consumption. The mega is primary because of my bad skills, with the uno and the used libraries I didn’t have enough RAM. I know, shame on me… 
