RAK 4631 - Reset Pin / JLink

WisBlock
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Please include the following information, in order for us to help you as effectively as possible.

  • What product do you wish to discuss? RAK4631

  • What firmware are you using? NRF Connect SDK + Zephyr OS

  • What firmware version? RUI3 Bootloader has been flashed via Jlink

  • Computer OS? Windows 11

Hello,

I am have been having an issue with the reset pin on the RAK4631 board. The board seems to get suck in a reset loop after powering on, until I manually tap 3.3v onto the reset pin with jumper. After tapping the pin it becomes “unstuck” and functions normally.

The reset pin is sitting at 2.2v when idle. I am wondering if that may not be high enough to be a logic high? I have tested the 10k resistor and 100nf cap and both are fine.

I am not sure if it is a faulty board/hardware, or if there is an issue with the firmware. Any advice would be appreciated.
Thanks.

2

Welcome to the forum @corey

If you flash a “normal” WisBlock Bootloader & application, is it the same?
If it works normally, it might be a wrong setup in your Zephyr setup. But I can’t help with that.
You can have a look into our Amazon Sidewalk firmware example. That uses Zephyr and run’s fine on a RAK4631 WisBlock.

3

Hi Bernd,
Thank you for your prompt response.

The issue has resolved after flashing a hexdump that you provided in the thread “Upgrade to RUI3 failing on RAK4630” - RAK4631-RUI3-V4.1.1-Flash-Dump.hex

I am now able to flash my Zephyr application and reset the board without issue, so I must have had the wrong bootloader version?

I was previously using bootloader_nrf52840.hex, which I downloaded from RAK-nRF52-RUI/prebuilt at main · RAKWireless/RAK-nRF52-RUI · GitHub, as my board initially came installed with the main Arduino bootloader.

For completeness, can you please confirm the bootloader version that I should have use to upgrade to RUI3?

Thanks,
Corey

4

The bootloader is in our Download Center in the “Bootloader Upgrade” folder ==> rui3_nrf52840_bootloader_latest.zip.

I usually use the “RAK4631-RUI3-V4.1.1-Flash-Dump.hex” you found in the other thread and flash it with JLink when switching between RUI3 and Arduino. That file includes bootloader, softdevice and application code.

Not sure if the bootloader required for Zephyr is the same or different.

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Thank you for your assistance!

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