Plain LoRa messages?

mike_c · January 31, 2022, 6:27pm

Hi, I’m relatively new to LoRa and would appreciate some guidance.

I have this Raspberry Pi Hat which I believe is the RAK2245.

I have set up the gateway successfully with both TTN and Chirpstack.

What I’d now like to do is read sensor values from this moisture sensor. It does not support LoRaWAN. My understanding is the values are sent as unencrypted LoRa messages. I have tried Chirpstack with gateway_frame_log_max_history=1 to try to log all messages to Chirpstack but never saw any messages come through.

Is there a python library I could use on the Raspberry Pi to just read any LoRa message that the gateway sees?

Thanks for your help,

Mike

cstratton · February 5, 2022, 5:14pm

The LoRaWAN gateways are really only intended to speak LoRaWAN, or at least operate in schemes of very similar design.

Probably you best bet would be to build MCCI LMiC for the ATmega on your sensor, so that it actually speaks LoRaWAN.

If you want to use its existing simpler raw LoRa scheme, you’ll likely find it easier to use another node-type LoRa board to do the capture as they recommend.

If you really, really, want to use the LoRaWAN gateway for non-LoRaWAN traffic, then you’ll need to look up the Semtech UDP protocol and learn how to implement that yourself in python so that your script can play the role normally played by a LoRaWAN Network server in receiving the raw reports from the gateway’s Packet Forwarder via UDP on the loopback network interface of the pi, and processing them. This is an achievable goal, but it’s a moderately complex programming project, and is not something there is or is ever likely to be any official support for.

github.com

Lora-net/packet_forwarder/blob/master/PROTOCOL.TXT

	  ______                              _
	 / _____)             _              | |    
	( (____  _____ ____ _| |_ _____  ____| |__  
	 \____ \| ___ |    (_   _) ___ |/ ___)  _ \ 
	 _____) ) ____| | | || |_| ____( (___| | | |
	(______/|_____)_|_|_| \__)_____)\____)_| |_|
	  (C)2013 Semtech-Cycleo

Basic communication protocol between Lora gateway and server
=============================================================


1. Introduction
----------------

The protocol between the gateway and the server is purposefully very basic and 
for demonstration purpose only, or for use on private and reliable networks.

There is no authentication of the gateway or the server, and the acknowledges 
are only used for network quality assessment, not to correct UDP datagrams

This file has been truncated. show original

mike_c · February 5, 2022, 10:32pm

Thank you for the engagement and the honest feedback. I think I’m going to take your advice and not try to do something that these devices are not intended to do.

I think my best bet is to have a separate LoRa gateway that is more P2P. This is probably outside the normal scope of this forum, but I’ve tried using this LoRa Raspberry Pi “bonnet” product as a the LoRa gateway but I don’t seem to get any signal from the moisture sensor over plain LoRa. I need to be able to get the sensor readings to MQTT, or somewhere else, and the documentation on the sensor’s site is so bad that I’m not wild about using one of the makerfab gateways. I’d prefer something better documented. Any suggestions appreciated, but again I know it is outside the scope of RAK stuff.

Thanks again for the pointers