Decode LMIC Encoded Byte Array w/o TTN

I am trying to transmit and receive message between a SparkFun Pro RF and a SparkFun ESP32 Ch-1 gateway.

Both of them supports LMIC (GitHub - mcci-catena/arduino-lmic: LoraWAN-MAC-in-C library, adapted to run under the Arduino environment) library. However, LMIC encodes transmit byte-array based on device address, network session key, and application session key. As I am not sending the data to TTN server I am not able to decode it. I am not interested to send these messages at TTN with the gateway as my device is not supported.

Now my question is,

  1. Can I transmit messages using LMIC without encoding it with device address, network and app session key? If yes how?
  2. If the answer of the first question is no, then is there a way to decode this encoded message without forwarding it to TTN?

Thanks in advance.


These cause huge disruption to the community network and we ask that you disconnect it immediately. Please search the forum for Single Channel Packet Forwarder or SCPF for details.

Not really, LMIC is written to a specification that specially does those things.

I’m not sure how you intend to not forward it to some sort of LoRaWAN network server. But yes, if you have the keys, you can decode it, there are several on GitHub.

Really what you are trying to do is Point to Point LoRa which you can encrypt the packet you send if you so desire, or just send the bytes as is, and save yourself all the pain of trying to bend LoRaWAN to not be LoRaWAN. The Sandeep Mistry repro does LoRa very nicely. This however is off topic for this forum so you will need to find resource to support you else where.

Thanks very much for your kind reply.

Could you please suggest a reliable repo for this?

Unfortunately this does not work with SparkFun devices.

I haven’t used any of them personally myself. If you list them, I will tell you the ones I’ve heard of or have indirectly used via various web utilities.

Can’t imagine why not - just a case of getting the pins right - but off topic for this forum.

1 Like