UG625: SiWG917 Firmware Fallback#

Overview#

The SiWx917 SoC (SiWG917) integrates two processors:

  • Network Wireless Processor (NWP) – Manages all networking and wireless stacks on independent threads and acts as the secure processing domain, responsible for secure boot, secure firmware updates, and debug lock.

  • ARM® Cortex®-M4 Processor – Dedicated to handling peripheral and application processing.

The SiWG917 uses two separate firmware images—one for the NWP and one for the M4 core. The Firmware Fallback Feature, introduced in WiSeConnect SDK v3.5.2, enables the device to store and boot from a backup set of NWP and M4 firmware images if the primary firmware fails or doesn't work as expected.

Note: The Firmware Fallback feature is supported only on 8 MB In-package Flash OPNs of the SiWG917 as listed in SiWG917 Datasheet

Firmware Fallback#

Firmware fallback feature is a mechanism that allows the SiWG917 to fallback to a previous version of its firmware if an update fails or when the updated firmware does not work as expected. This feature involves storing two sets of NWP-M4 firmwares denoted as Slot-A and Slot-B for easier understanding.

As part of the Firmware fallback feature enablement, the wiseconnect SDK from v3.5.2 would contain the below NWP firmwares:

Slot-A NWP firmwares:

  • <wiseconnect_SDK>/connectivity_firmware/standard/SiWG917-B.2.x.x.x.0.x.rps

  • <wiseconnect_SDK>/connectivity_firmware/lite/SiWG917-B.2.x.x.x.2.x.rps

Slot-B NWP firmwares:

  • <wiseconnect_SDK>/connectivity_firmware/siwx91x_slot_b_images/standard/SiWG917-B-SlotB.2.x.x.x.0.x.rps

  • <wiseconnect_SDK>/connectivity_firmware/siwx91x_slot_b_images/lite/SiWG917-B-SlotB.2.x.x.x.2.x.rps

Incase the firmware fallback feature is disabled, respective Slot-A image should be loaded during firmware update.

As part of the feature demonstration, the wiseconnect SDK provides four reference examples as listed below:

  • SoC M4 Firmware Fallback Updater: Fetches the M4 firmware slot information, controls the firmware slot image selection for bootup.

  • SoC M4 Firmware Fallback Updater Security: Fetches the M4 firmware slot information, controls the firmware slot image selection for bootup, on security enabled devices.

  • SoC M4 Firmware Fallback Slot-A: Executing from slot-A flash location, demonstrates OTA firmware update of the inactive slot (here slot-B), via (Transmit Control Protocol) TCP connection.

  • SoC M4 Firmware Fallback Slot-B: Executing from slot-B flash location, demonstrates OTA firmware update of the inactive slot (here slot-A), via (Transmit Control Protocol) TCP connection.

References#

For more information, refer to the following Silicon Labs documents:

Content#