Reset happens when trying to join network

Issue: When calling at+join, the startup message is showing up, same as on power up, so it seems that a reset is happening, when I try to join the network

Setup: RAK4200, firmware



Hi @XoverIoT , welcome to RAK forum.

May I know your setup? Is this a RAK4200Evaluation Board? Or is this a custom board with RAK4200 module?

I am using the RAK4200 Breakout Board V2.0, which is a evalboard. Nothing soldered on my own. Just connected 3,3V, GND, Rx and Tx.

Thanks for the info. Can you share me the commands you sent before at+join? Are you trying OTAA? ABP? What keys have you configured? Did you follow the quickstart guide?

See attached picture.
Yes, I followed the quick start guide.

Ok. Let me help you troubleshoot it. Does it always restart when you send at+join? What USB-UART converter are you using? Can you try a different one? Can you try connect on a different USB port? Can you confirm if the Gateway is ok?

What are you using for the 3v3 power source?

Many USB UARTs have a 3v3 output that can only supply very low current loads, something like a LoRa module trying to transmit powered by that would probably cause a brownout reset.

Yes it is always happening on every at+join.
The gateway is ok, because a dragino sensor is fully working with TTN in parallel.
The serial line is fully working, I am using original FTDI Converter cable.
I can try another USB connector tomorrow, but any other command is behaving like expected, so I don’t see much chance.
Before I fully got the gateway working, the behaviour was, that Error 99 was showing up after some time after at+join.
2morrow I can do a join with the gateway powered down, as a cross check.

If you were using that for a power source and not just communication, it explains the problem, as that would not be able to source enough power to survive transmission.

You need to use a more suitable power source.

Error 99 means you are trying to transmit packet but still not yet properly joined.

I doubt it is the power source but having an external one wont hurt. When you send at+join, do you see join request on the network server?

You can also try to reupload the firmware. Or erase all in stm32cubeprog then reupload the .hex. It is not hard to do anyway.

As @cstratton says, an FTDI USB to serial won’t cut it - it can only provide 50mA maximum and the RAK4200 data sheet says it needs 68.4mA to transmit.

Ironically, many of the cheap CH340G USB to serial devices are much much better as they usually put a small 3.3V LDO on the board so you can get 150mA.

Well, the module is not powered by the FTDI, but from an external power supply. But you pointed me into the right direction.
I was too carefull with setting the current limit. → 50mA is not enough.
So yeah, problem was fixed by increasing the current setting.
Joining network is working now.
I am really surpised about the current consumption, as our own RF modems for Sigfox are only consuming 30mA peak.
Seems like LoRa want’s some more power :wink:
Thanks for the help, very good support experience. We feel very good with choosing RAK modules for our LoRaWAN designs from now on.

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It seems you got a good power supply cutting 50mA burst instantly.

I am using FTDI converters on my breakout boards and got no issues joining.

Good thing with RAK4200 module is you’ll get 1.5uA sleep current. Your battery can service you for a long time :slight_smile: