RAK3272 No UART Response

Sorry for all my posts here, but I think I may have fried my RAK3272 and I’m wanting to know if it’s dead or if I accidentally reset something internally that can be fixed.

I had it connected to a rpi with four jumpers including 3.3V, ground and both UART2 pins. The ground pin came disconnected due to a loose jumper cable, but when I plugged it in I’m pretty sure I had it plugged into one of the SWDIO/SWCLK pins close to the ground pin. I didn’t notice for a few minutes and it did get warm but doesn’t seem that would be enough to fry the board? I tested resistance across the traces with a multimeter and they all had several Mega ohms of resistance so shouldn’t have been more than a few mA/microAmps?

Tried both 115200 and 9600 bauds on rak serial tool with no response to AT commands, and then tried flashing the latest firmware but it times out.

Any help would be great!

Thanks in advance

Hi @Dizzy ,

If you have debugger tools like STLINK or JLINK, you can try to check the module if can still be detected. If you do not have those, you can try connecting it to STM32CubeProgrammer via UART connection. We have a tutorial here - STM32CubeProgrammer Guide for RAK Modules | RAKwireless Documentation Center.

It is hard to say if it is damaged or not though (my personal opinion), I doubt that putting GND to SWD pin can kill it.

I tried using the RAK serial tool at first with no luck, I now installed the STM32 programmer and this is what it says when I attempt a UART connection:

I have the boot pin jumped to 3.3V on a breadboard and verified it was receiving the voltage. I’m using the UART tool from RAK’s website and it works with my second module fine but not this one