STiRoT Boot Time

[halwizard]

Hello,

I'm a developper from the CEA using STM32H573 and I am characterizing the chip boot time in various configurations. With STiRot activated (250 MHz and a 128 Kb image) I found 31 ms which is twice as much as the boot time indicated in the documentation (16 ms ; AN6007 - Table 5. Boot time performance).

I would like to know how the STiRoT boot time values from the documentation were obtained, to see if I am missing something here.

Thank you in advance,

Best regards

[TetrasLyre]

I'm also interested in the answer to this question

[Jocelyn RICARD · Accepted solution]

Hello @halwizard ,

I checked these figures

I added a GPIO change at the beginning of the SystemInit() of the application

I measured the delay between the reset signal and this GPIO change.

For 128KB 250 MHz I get 13,58ms and for 250KB at same frequency I get 17,29ms

So, my results look not too far from what is expected.

Did you test with product state set to CLOSED ?

Also, did you double check the frequency in xml configuration file because default is 200MHz not 250MHz ?

Difference is not so big though (around 10%)

Best regards

Jocelyn

[halwizard]

Hello @Jocelyn RICARD , 

Thank you for your precise answer. Indeed product state was set to OPEN, and with CLOSED state I was able to reproduce your results.

By the way, in the case the DA OBK was provisioned in OPEN, is it safe to directly go to CLOSED (without loosing DA OBK as it is the case when going to PROVISIONING) ?

Best regards

[Jocelyn RICARD]

Hello @halwizard ,

this is good initiative to ask the question as you must not do this :)

On STM32H573 which has crypto accelerators, the OBKeys are encrypted.

When you provision in open state this encryption is done using a fake DHUK that is the same on all devices.

Once device moves in provisioning state, the real DHUK is used.

So if you close the device in such state you will brick it.

What you can do is moving to provisioning state and reprovision all the OBKeys binaries before moving to closed but launching the provisioning again is safer.

Best regards

Jocelyn

[halwizard]

Good to know, thanks a lot :)

Best regards