Looking for BLE OTA Bootloader information

[Albert_0]

Hello all,

I'm looking for some information about a BLE bootloader for an NRF52840 (u-blox NINA) device. 

I do little debugging at this stage and would like to be able to update the firmware over BLE. The unit where our NRF PCB is located doesn't really allow for using j-Link for updates, although we can make a few concessions.

I've been looking for BLE Bootloader information for NRF chips, so far I understand that:

- NRF does not provide a ROM bootloader

- The bootloader has to be compiled and flashed into the microcontroller, before the application can be flashed.

- There are two types of bootloader available... is that right?

I'm working on Windows 11, the NRF SDK 2.5 and Zephyr. Can you provide me with an up to date example / tutorial and information? I'm a bit confused with what I've found so far. Basically I need a simple BLE buttonless bootloader that I can jump into from the application, and that re-starts the application after a successful update.

I may have more questions moving forward... 

Cheers,

Alberto

[Vidar Berg]

Hello Alberto,

- NRF does not provide a ROM bootloader

Correct.

- The bootloader has to be compiled and flashed into the microcontroller, before the application can be flashed.

In the nRF Connect SDK, the bootloader (MCUBoot) can be built and flash along with the main application. The bootloader is included in the build by adding 'CONFIG_BOOTLOADER_MCUBOOT=y' to the prj.conf file. The bootloader will then be built as a 'child-image' to the parent image (see Multi-image builds).

To enable support for DFU over BLE, you also add CONFIG_NCS_SAMPLE_MCUMGR_BT_OTA_DFU=y. 

For more details about FOTA on the nRF52, you may refer to the 'FOTA updates' chapter here: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.5.2/nrf/device_guides/working_with_nrf/nrf52/developing.html#fota-updates

- There are two types of bootloader available... is that right?

Yes, in addition to MCUBoot, we have the nRF Secure Immutable Bootloader which can be used as a first-stage bootloader. 

Cheers,

Vidar

[Albert_0]

Thank you Vidar for the quick response. I will have a look at that information and see if I can integrate the bootloader into our project.

What are the main differences between MCUBoot and the Immutable Bootloader? I'm still a bit in the dark about that.

Can I add the Immutable Bootloader alongside the main application in the nRF SDK?

Cheers,

Alberto