Hi Nordic Support Team,
We are currently developing a product based on the nRF54L05 SoC using nRF Connect SDK (NCS) v3.0.0. Our application is facing significant Flash memory constraints; the device only has 500 KB of Flash, and we need to implement BLE OTA (Over-The-Air) firmware updates.
We initially tried the standard MCUboot dual-slot (primary + secondary) approach. However, this consumes most of the available Flash, leaving insufficient space for our application. As a result, our application code cannot fit in the primary slot. We also attempted to configure the system in single-slot mode using CONFIG_SINGLE_APPLICATION_SLOT=y to reclaim the secondary slot for our application. Unfortunately, this leads to a Kconfig warning indicating a conflict between MCUMGR_GRP_IMG (selected by NCS_SAMPLE_MCUMGR_BT_OTA_DFU_MCUBOOT) and MCUBOOT_BOOTLOADER_MODE_SINGLE_APP:
"warning: MCUMGR_GRP_IMG (defined at subsys/mgmt/mcumgr/grp/img_mgmt/Kconfig:15) has direct dependencies FLASH && IMG_MANAGER && !MCUBOOT_BOOTLOADER_MODE_SINGLE_APP && MCUMGR with value n, but is currently being y-selected by the following symbols: - NCS_SAMPLE_MCUMGR_BT_OTA_DFU_BACKEND_MCUBOOT..."
It appears that BLE DFU functionalities are incompatible with the single-slot configuration, a limitation we observed in previous DevZone threads.
Therefore, we would like to ask:
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Is there any officially supported method or workaround to perform single-slot BLE OTA on the nRF54L05 with NCS v3.0.0? Or is the current standard recommendation for nRF54L05 still limited to serial DFU (UART) only, as noted in previous discussions? We understand that single-slot update is supported for Serial Recovery, but we need an OTA solution.
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Are there any other techniques or upcoming features in NCS (e.g., image compression or a minimal single-slot SMP server) that could help us fit both the bootloader and a BLE DFU-capable application within the 500 KB Flash of the nRF54L05?
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If internal single-slot BLE OTA is not feasible, what are the recommended workarounds?
Any guidance or suggestions you could provide would be greatly appreciated.
Thank you for your support.
Best Regards,
Ryan