[FIXED] RAK7200 GPS Tracker - "Parameter Not Found"

Hey folks, we had an issue with our 7200 this morning whereby LoRaServer.io (our own installation) couldn’t interpret the LPP payload correctly.

As a result, I’ve reflashed the firmware using the guidance in this thread, however I now can’t join the network.

Issuing at+join results in Parameter not found (this is also seen on boot-up) even though other commands (lora:status and device:restart for example) work perfectly well.

Any ideas what might be causing this? I’m running the latest version of both the BOOT and firmware, BOOT was flashed via the STM32 Cube tool, the firmware was flashed via the LoRaButton Firmware Update tool.

This is the output when the device resets:

______  ___   _   __  _    _ _          _               
| ___ \/ _ \ | | / / | |  | (_)        | |              
| |_/ / /_\ \| |/ /  | |  | |_ _ __ ___| | ___  ___ ___ 
|    /|  _  ||    \  | |/\| | | '__/ _ \ |/ _ \/ __/ __|
| |\ \| | | || |\  \ \  /\  / | | |  __/ |  __/\__ \__ \
\_| \_\_| |_/\_| \_/  \/  \/|_|_|  \___|_|\___||___/___/
S76G_B version:
LIS3DH init successed!
DMP is disabled 
LPS22HD not found!

Selected LoRaWAN 1.0.2 Region: EU868
Initialization OK,Current work_mode:LoRaWAN, join_mode:OTAA, Class: A
Parameter not found.

and the output from at+get_config=lora:status is as follows:

==============LoRaWAN Status List================
Region: EU868
Send_interval: 30s
Auto send status: true.
Join_mode: OTAA
DevEui: <MY DEV EUI>
AppEui: 0000000000000000
AppKey: <MY APP KEY>
Class: A
Joined Network:false
IsConfirm: false
Work Mode: LoRaWAN
AdrEnable: true
EnableRepeaterSupport: false
Current Datarate: 5
Primeval Datarate: 5
ChannelsTxPower: 0
UpLinkCounter: 0
DownLinkCounter: 0
AntennaGain: 2.15
===================List End======================

Fixed it, the missing parameter was the app_eui key.

Perhaps in the next version of the firmware we could have an indication as to which parameter is missing?

Hi @MBConsultingUK,

It would seem you are missing some key concepts on how LoRaWAN works. The parameter was missing as it has not been entered. This is explained in the manual, as a matter of fact none of the parameters required to join a networks in either OTAA or ABP mode have been entered simply because they are specific for your network of choice.
The app_eui you are referring to is the Application EUI, which is a unique identifier for the application. Here is a brief explanation:

In short some parameters can not be pre-configured and are up to the user(you) to input, this is simply how the network works I believe


Thanks @Hobo - I’ve been using LoRaWAN for over three years now, and understand that an AppEUI, DevEUI, and AppKey are required for OTAA, however with other devices an AppKey of all zeros has been acceptable as a test value at both device and server side.

I’ve got it all working and have documented it as above, however it would be great if the next release of the firmware told end-users which parameter was not set, rather than just outputting Parameter Not Found, when the command at+set_config=lora:status shows that there is a value for all three of these fields (even if they are set to all zeros!).

The device looks great, I’m now awaiting a firmware without the bug in it around the Cayenne LPP message format, and once that’s done I’ll have a blog post written up about it.

Thanks for all the hard work on this, I’m hoping that this device will form a central part of our Farm Management Solution around asset tracking given the price-point, and if you need beta testers then I’m more than ready to help.

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