SWRU543B January 2019 – June 2025 CC3230S , CC3230SF , CC3235MODS , CC3235MODSF , CC3235S , CC3235SF
The device supports a maximum size of 1022KB for the user application. The application binary, along with a signature, must be supplied to the programmer. The signature is authenticated (or chain-authenticated) by a Root CA in the TI-provided certificate store for programming. This is to inhibit the execution of an image from an unknown vendor.
The CC323xSF bootloader, on every exit from power-on or hibernate, checks the integrity of the exiting (and marked-valid) user application image binary on the on-chip flash against the auto-generated SHA-256 of the image on serial flash, which is saved during the program-and-update phase of the on-chip flash. If a mismatch occurs, the on-chip flash is mass-erased to protect the user application binary.
The SHA-256 hash makes a link between the image on the on-chip flash and the serial flash, which is then linked to the device using a device-specific key. Any change in the serial flash after the image was copied to the on-chip flash will be detected and will either be mass-erased or updated to the new image on serial flash.
Figure 21-13 shows a simplified view of the image transfer process, from serial flash to on-chip flash in a CC323xSF device.
Figure 21-13 On-Chip Flash Programming and Update