TIDUE59A May 2018 – September 2020
The TIDC-01005 uses two additional security enablers to help protect the file system during infield software updates, such as OTA software updates. The CC3220S provides the option to create files as failsafe files, which means that two banks of memory on the external serial flash are reserved for the file when it is created. Reserving two banks of memory allows two copies of the file to be stored at the same time. During OTA updates, the new copy of a failsafe file is written to the second bank of memory alongside the current version of the file. After the download completes, the new version of a failsafe file is committed (set as the active version) only after the application verifies the file is intact.
The CC3220S also provides a feature called bundle protection, which developers can use to help keep the overall system integrity while updating a collection of failsafe files referred to as a bundle. Because software testing is typically performed on a system with a specific set of file versions, it is important for all files in an update to be applied at the same time. Bundle protection provides the developer with the ability to commit or rollback all files in a bundle together, to prevent the system from ending up with a file system containing a mixture of multiple software versions.
Using failsafe files and the bundle-protection feature is important for electronic smart lock designs that implement OTA updates, because it helps developers maintain the system integrity and ensure the lock remains functional at all times. The OTA update demonstrated by the default TIDC-01005 application uses bundle protection for all files in the update.