ST.box is on track with the most recent software solutions also in the field of Over-the-Air programming: firmware can be updated in a secure way on the ST.box. But let's see in which way.
The BLEFOTA firmware can be updated Over-The-Air (FOTA) through an Android/iOS device via Bluetooth using the STBLESensor application: in more detail, the app sends the update and associated cyclic redundancy check (CRC) value, which the BLEFOTA checks against the hardware cyclic redundancy check calculation unit on the STM32L4 processor to ensure integrity. If the CRC calculation matches the STBLESensor CRC value, the new firmware is written at the beginning of the third Flash region. A “magic number�? signals to the STBLESensor that a firmware update has been received and checked, and is ready to replace the current BLEFOTA firmware.
The BootLoader checks whether the "magic number" is present and, if the case, the BootLoader replaces the content of Region 2 (previous BLEFOTA firmware) with the content of Region 3 (new BLEFOTA firmware), then deletes the "magic number" present on Region 3 and restarts itself. If the magic number is not present, the BootLoader jumps to running the actual BLEFOTA firmware present on Region 2.
