RAK3172 (v4.2.1) not responding after power failure

LPWAN Modules / EVBs RAK3172
1

Morning
I have been testing the new RAK3172 RUI3 firmware version 4.2.1 and I have had 3 cases where the module has become unresponsive to AT commands. Even after a reset or reprogramming the module will not become responsive again.

We are using a battery to power our devices and in the first 2 cases the modules became unresponsive when the battery started going flat. In the last case I used a power supply to power our device but I limited the current to 80mA and the issue occured again after an transmission attempt. Clearly there is an issue when the module is awake and the power to the module dips.

I have seen this before with earlier versions of the RUI3 firmware (see RAK3172 not responding after power failure ) however this issue seemed to disappear with version v4.0.6.

Looking at the current draw on our device with an unresponsive module I can also see a weird square wave appearing where the device draws an extra 0.5mA for 122ms then 0mA for 122ms then the extra 0.5mA for another 122ms.

2

Did you try a chip-erase with STM32CubeProgrammer or a JLink?

80mA can be to less for a LoRa transmission, depending on your TX power setup. It can put the MCU into an undefined state because the supply voltage is dropping too low. You should make sure that your battery can supply enough current and that it can handle steep rise in the power consumption.

What battery type are you using?

For the unresponsiveness, I will forward the issue to our R&D team.

1 Like
3

Hi Bernd
Did you have any response on this issue from your R&D team?
With regards to your questions I tried the chip-erase with STM32CubeProgrammer using an STlink. We are using a lithium battery, hence I limited the current to 80mA to simulate a low battery condition.

4

Ticket is still open.