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Locked Flash

georgiad
Prodigy 100 points

I have a project with a 2812. I lock the flash, but I need that the end customer makes a calibration of the unit.

This means that the program should be able to write some variables in flash, which is locked. Is it possible

to write data to a locked flash from the internal Ram? And if not, is it possible to lock only a part of the flash?

Thanks

  • 0
    TI__Guru* 93800 points

    If the code security module is locked, then only secure memory can access secure memory. 

    This means that if the flash API is running from secure RAM it can modify the flash.  So the question is how to get it into secure RAM.  One way is to have a loader in the OTP (which is also secure).  You could call this loader to pull the API in from somewhere extermal into secure RAM.  Another way is to have the API stored in the flash or OTP and then copy it into secure RAM.

    -Lori

  • 0 in reply to Lori Heustess
    Prodigy 100 points

    Thank you very much Lori for your reply

    Now my question is: is it possible to write data in a secure RAM, for example from the serial port?  What I need is that after a period of time, my customers make some

    measurements of my unit, pass the results in the unit  through the serial port  and write them permantly in the Flash. Is there any example of the code needed?

     

    Thanks again

     

  • 0 in reply to georgiad
    TI__Guru* 93800 points

    Any code running from secure memory can write to and read from secure memory.  So, for example, if the ISR servicing the serial port is in secure memory the ISR can put put the data in secure memory. 

    - Lori

  • 0 in reply to Lori Heustess
    Prodigy 100 points

    Thanks for the reply. I will check it.