mcumgr relay

[Benjamin]

Does mcumgr support relay functionality? On one device, I have a firmware image stored in external flash connected to a 9160 and need to relay that image via UART to an on-board 52833 in order to BLE-FOTA another device, all running zephyr. Is there a simple way to leverage mcumgr to relay the image through the "middle" 52833?

[Amanda Hsieh]

Hi, 

The mcumgr does not directly support relay functionality. However, The Zephyr Project supplies mcumgr as a SMP Client. The mcumgr library can help with receiving the images and writing them over Bluetooth Low Energy, UART, and UDP over IP.

To communicate with MCUmgr, you need an SMP Client. An implementation is available in NCS. It is demonstrated in this sample: Bluetooth: Central SMP Client.

If you want to work with NCS's built-in solution, your nRF9160 module needs to support an SMP Client. You might be able to port it from NCS's implementation. 

You can use  the SMP Server Sample on the nRF52833 Peripheral device, swapping out the transport layer from Serial to Bluetooth. This sample includes several Kconfig fragments to enable different MCUmgr transport methods, such as overlay-serial.conf for UART transport. 

My colleague, Hellesvik, provides some such samples here: https://github.com/hellesvik-nordic/samples_for_nrf_connect_sdk/tree/main/bootloader_samples .

Please note that these samples on Hellesvik's repository are unofficial, not tested, and only maintained during contributors' free time.

Regards,
Amanda H.

[Benjamin]

This is great info, thank you!