CC2745R10-Q1: cc2745 HSM's bin file is lost

Hi James,

james zhou said:

When using the CC2745, we occasionally encounter problems with missing HSM.bin files.Trying to understand if there are any mis-operations that cause this to happen, such as continuous flash burns, and if ti can explain the circumstances that would lead to the loss of hsm.bin so that we can avoid these operations.

I'll assume that you mean that the HSM firmware on the device is missing, but if my understanding is incorrect, please let me know.

If two Chip Erase operations are done back-to-back without flashing any software in-between (specifically, a valid CCFG and SCFG), the HSM firmware will be erased. 

The first Chip Erase will invalidate and erase the CCFG and SCFG which provide the protections for the HSM firmware region in flash. Because the CCFG and SCFG are now erased by the first Chip Erase, the second Chip Erase will remove the HSM firmware.

The best way to avoid this is to flash something in between every chip erase:

Avoid: Chip Erase > Chip Erase > Flash : firmware will have been deleted.

Do: Chip Erase > Flash > Chip Erase : HSM firmware will be retained.

I hope that makes sense, and if you have any further questions or need some clarification, let me know.

Best,

Nima Behmanesh