NumWorks open source calculator

[ijabbott]

(08-30-2017 02:51 PM)Claudio L. Wrote:  

(08-30-2017 05:35 AM)ijabbott Wrote:  There seems to be some question about whether or not it can only run digitally signed firmware due to "exam mode" requirements (https://www.reddit.com/r/numworks/commen...tty_easily). This may put the kibosh on projects such as porting Free42, WP-34s, WP-43s, NEWRPL, etc.

I may be wrong, but as far as I can see the STM32 doesn't have secure boot, firmware encryption, or anything like that. There's a cryptographic accelerator module that can be used by software to speed up encryption, but the encryption still has to be done by the firmware and there's nothing protecting that. Disabling signature check in the firmware should be as easy as bypassing erase on exam mode.
Kinetis by NXP have secure boot, but STM32F4 doesn't as far as I know.

Then perhaps it's just a matter of bypassing whatever "official" update mechanism the firmware provides.