How to bring data out of downlink

jordan17 · October 3, 2023, 12:34pm

Hello, I’m a beginner with LoRa, I don’t know if it’s possible, but I want to bring out the data I send to my Lora Node with MQTT in variable on arduino to allow to control a relay depends on the data received. I can add information if it’s not clear. Thanks You and sorry for my English.

LoRaTracker · October 3, 2023, 5:44pm

Some basic information would be useful.

Can you give details of the actual LoRa ‘node’ you are using and the software or libraries you are using on this node ?

clv · October 3, 2023, 6:49pm

Maybe you are confusing LoRa with LoRaWAN. This forum is for LoRaWAN. Downlinks are limited to 10 per day.

bertrik · October 3, 2023, 8:56pm

Yes, it is possible to receive downlink information on a node. For the default mode, class A, a data exchange consists of a device uplink message, followed by an optional downlink message from the network to the device. For example, in the MCCI LMIC stack, you can check in the “transmission complete” event callback if the network sent data back, see:

github.com

mcci-catena/arduino-lmic/blob/master/examples/ttn-otaa/ttn-otaa.ino#L156


      
          || 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);

(the “if (LMIC.dataLen) {” part)

jordan17 · October 4, 2023, 5:16pm

Thanks you all, first I don’t know this forum is only for LoraWan, but for the code I already see this but I don’t really how does it work, because at this time I only sent downlink to my node with mqtt by logging in my gateway server, I see a downlink on my node but i don’t see the downlink with my gateway.

clv · October 6, 2023, 8:19am

Sorry, I don’t understand what you did or the problem. Node receives the downlink but you can’t see the downlink on the gateway logs?

What code did you use on the node? You can use LMIC as stated from bertrik to process the downlink. We need details for the setup to understand.

jordan17 · October 9, 2023, 9:35am

Thanks you for your answer, I found the solution with do if data receive function.