RAK3172 | RUI3 Bootloader + App Code Flash successful but AT commands and upload via USART2 not working

LPWAN Modules / EVBs
1

Hi RAK Team,

We have designed a custom board with RAK3172 and it had RUI4.0.3 as default. After doing some initial playing with the RAK3172 I was able to update it via Arduino RUI3 platform using USART2 for updating the firmware and also able to issue AT commands to it. I am using ST-Linkv2 to upload the code to the chip.

While doing further tests, the chip stopped responding to AT commands, so I tried to flash RUI3 bootloader to it, using this file via STM32CubeProgrammer - https://downloads.rakwireless.com/RUI/RUI3/Image/RAK3172-E_latest_final.hex

The STM32CubeProgrammer tool is able to upload the file successfully but the RAK3172 still doesn’t respond to AT commands nor is able to upload program on Arduino via USART2.

I have followed the steps according to How to Guide: STM32CubeProgrammer for RAK Modules - RAKwireless Learn

I had also tried using WisToolBox but the chip is not getting identified.

Could you please advise if the method is correct of if any additional steps needed to be considered?

2

Welcome to RAK forum @gracengeer .

Some things you can try/check.

  1. Have you tried to full chip erase first before upload the RUI3 firmware?
  2. It is common mistake not to remove the boot pin in pull up state when UART2 is used with STM32CubeProgrammer. Can you confirm you removed it?
  3. If you successfully uploaded the FW via UART2, it seem that those pins are not damaged. Do you have any changes on the hardware (since it is a custom board) when the issue occur? Maybe power source? maybe some connections?
  4. Did the issue occur on multiple boards you have? Or only on one?
3

Hi @carlrowan thank you for reply.

  1. Yes, I did a full chip erase before uploading the RUI3 firmware.
  2. The BOOT pin is floating in our current design.
  3. Yes the pins were not damaged earlier and I was able to upload the code on a fresh chip and also subsequently multiple times until it stopped working at one point
  4. We got this issue on two of our boards as of now with same behaviour.

I was trying to understand if there any possibility of STM32 flash working fine but some particular reason of RUI3 failing to work.

4

Hi @gracengeer ,

When the module stop responding, do you need to fully upload again a new RUI3 firmware? Or reset is enough for the AT commands to be accepted again?

Do you have any possible condition when it stopped? What custom FW did you upload and what AT commands you send to the module? Could it be related on the custom FW?