nrf52833 enter bootloader/dfu mode over uart

[MatthijsB]

Hello,

I am using an nRF52833 in a project where and i want to be able to update it via another mcu (STM32H7) over uart. The STM32 has received and saved the new hex file for the nRF and i want to update the nRF over uart.

In the integration manual I've read it specifies that to enter the DFU mode the switch_2 pin has to be pulled low when resetting the nRF to make it enter the bootloader mode.

I have confirmed the pin is set low from the STM32H7, however, the nRF52833 does not seem to enter the bootloader mode and jump straight to the application. The flow i use is:
- pull switch_2 LOW
- set reset_n LOW
- set reset_n HIGH

The behaviour i expect is it waits ~30s in DFU mode before entering the default application.

I have flashed the default bootloader hex onto the chip. The default program i run on it is programmed via Zephyr.

Am i missing something? Can anyone help me find the issue?

Thanks in advance!

[Vidar Berg]

Hello,

Is the integration manual you referred to internal to your company or from a third party? Also, where does the "default bootloader hex" come from? The reason for asking is that our 52833's are shipped blank from our factory and don't have any default bootloader.

Thanks,

Vidar

[MatthijsB]

Hi,

Thanks for your reply.

My bad, the used component is a NINA-B400, with the nrf52833 as chip inside. The integration manual was from ublox, along with the provided bootloader, which i assumed was from nrf (again, my bad sorry).

Kind regards,

Matthijs

[Vidar Berg]

Hi,

Unfortunately, I do not know anything about the bootloader they use. Have they made the source code available?

Kind regards,

Vidar