🛠 Rejoindre The Things Network (OTAA)

Objectives

Join a public LoRaWAN network (The Things Network) using OTAA with the MKRWAN library: register the device with its deviceEUI, send uplinks and receive downlinks, read RSSI/SNR. This is the primary purpose of the board — no Wi-Fi, no HTTP here, only LoRaWAN Class A.

Hardware

• 1 MKR WAN 1310 board + 868 MHz antenna
• A The Things Network account (or TTN Stack) and a created application
• Reference example: MKRWAN > LoraSendAndReceive

Full code

// OTAA The Things Network — MKR WAN 1310
#include <MKRWAN.h>

LoRaModem modem;
String appEui = "0000000000000000"; // EUI de l'application TTN
String appKey = "00000000000000000000000000000000"; // APP_KEY OTAA

void setup {
  Serial.begin(115200);
  while (!Serial);
  if (!modem.begin(EU868)) { Serial.println("Module KO"); while (1); }
  Serial.print("deviceEUI : "); Serial.println(modem.deviceEUI);
  if (!modem.joinOTAA(appEui, appKey)) {   // blocage jusqu'au join
    Serial.println("Join echoue : rapprochez-vous d'une fenetre");
    while (1) {}
  }
  Serial.println("Joint !");
  modem.minPollInterval(60);
}

void loop {
  while (!Serial.available);
  String msg = Serial.readStringUntil('\n');
  modem.beginPacket;
  modem.print(msg);
  int err = modem.endPacket(true);   // true = uplink confirmé (ACK)
  Serial.println(err > 0 ? "Envoye !" : "Echec (duty cycle ?)");
  if (modem.available) {           // downlink reçu en fenetre RX
    char recu[64]; int i = 0;
    while (modem.available && i < 63) recu[i++] = modem.read;
    recu[i] = '\0';
    Serial.printf("Downlink: %s\n", recu);
  }
  Serial.printf("RSSI=%d SNR=%d\n", modem.rssi, modem.snr);
  delay(120000); // le firmware impose 1 émission / 2 min max (EU)
}

Expected verification

"Joined!" appears after a few seconds to a few minutes; uplinks appear in the TTN live data with RSSI/SNR. A downlink scheduled on TTN returns in the RX window following the uplink.

Common errors

• joinOTAA failing even when everything is correct: known bug with false errors (MKRWAN issue #139) — retry, place the board near a window, verify that a TTN gateway covers the area.
• Sending more than one message every 2 minutes: the firmware imposes this duty cycle floor, which cannot be changed; transmissions are rejected.
• Inverted keys (APP_KEY in appEui) or in text format instead of hexadecimal.
• ABP: regression reported since MKRWAN 1.0.15 (issue #85) — prefer OTAA.
• After ~255 transmissions, TX blocking (frame counter bug, issue #141): see the advanced tutorial on workarounds.