Example of C-based client when DFUing a nRF52840 via UART

RE: Example of C-based client when DFUing a nRF52840 via UART

Amanda Hsieh — Wed, 05 Mar 2025 14:59:09 GMT

Unfortunately, we/Nordic don't have such tools. Maybe you could seek help on Discord mcumgr channel: https://discord.com/invite/Ck7jw53nU2.

RE: Example of C-based client when DFUing a nRF52840 via UART

Alex-Uzinakod — Wed, 05 Mar 2025 14:41:46 GMT

I can't find it in the nRF documentation but there's details in the official Zephyr documentation:
- https://docs.zephyrproject.org/latest/services/device_mgmt/smp_protocol.html

- docs.zephyrproject.org/.../smp_transport.html

RE: Example of C-based client when DFUing a nRF52840 via UART

ste2108 — Wed, 05 Mar 2025 08:39:32 GMT

Dear Amanda,

Thank you for your answer. Correct me if I am wrong: even though the DFU over UART can be enabled in Zephyr running on the nRF52840, the only chance users have in order to understand the sequence of packets to be exchanged between client (PC) and host (MCU) is extracting it from third-parties clients, cause neither Nordic nor Zephyr provide it?

Kind regards,

Stefano

RE: Example of C-based client when DFUing a nRF52840 via UART

Amanda Hsieh — Tue, 04 Mar 2025 16:41:19 GMT

Hi,

The DFU over UART course demonstrates how to enable mcuboot Serial Recovery via UART and add DFU from the application. The related functions within the mcumgr library will be loaded into the project according to those configurations. Unfortunately, there is no such documentation as your requirements. Hope the MCUmgr transport SMP API can help.

Regards,
Amanda H.

RE: Example of C-based client when DFUing a nRF52840 via UART

ste2108 — Tue, 04 Mar 2025 07:31:56 GMT

Hello Alex,

thank you for your answer. Yes, we have taken a look at both the DFU over UART example (which I use to adapt my project with the proper configuration) and the protocol definition. What we lack is the sequence of operations we need to perform to update the device, and possibly the related functions within the mcumgr library that we need to use at each step. I am sniffing the packets but honestly validating the sniffed packets and associating them to the DFU sequence can be really painful. I believe that at least a sequence of needed operations should be provided by Nordic in a tech document.

Regards,

Stefano

RE: Example of C-based client when DFUing a nRF52840 via UART

Alex-Uzinakod — Mon, 03 Mar 2025 18:47:56 GMT

To the best of my knowledge, a pure C lib to DFU over UART doesn't exist at the moment.

We'll face the same issue in a project of ours. The protocol it self is documented here: https://docs.nordicsemi.com/bundle/ncs-latest/page/zephyr/services/device_mgmt/smp_transport.html

You could snif the UART bus using either a logic analyzer or Wireshark to validate that the documentation is acurate.

You could also use the DFU from application method mentionned here: academy.nordicsemi.com/.../