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How to Erase Flash when CSM Passwords are Corrupted

SADGUNA RAO KURRA
Prodigy 80 points
Other Parts Discussed in Thread: TMS320F28335

When Programming the TMS320F28335 in Flash Using On-Chip Flash Programming utility(CCSV3.3),the erase Operation is Interrupted so my CSM passwords are Corrupted.

I can't access the Flash as it is Locked.

But in System Control & Interrupts User Guide provided by TI it is mentioned that

If a device is reset while the password locations are all zero or an unknown value, the device
will be permanently locked unless a method to run the flash erase routine from secure
SARAM is embedded into the flash or OTP. Care must be taken when implementing this
procedure to avoid introducing a security hole.

Can any one know How to Implemet this method if you please help me

Thanks in Advance

Regards,

Sadguna Rao.K



 

  • 0
    TI__Intellectual 1950 points

    Sadguna

    Can you let us know how the erase got interrupted? What the statement in the Sys control Guide means is, the corrupted passwords can be erased only if an erase routine is already embedded in the flash before the corruption occurred. This procedure involves programming flash with the routine, which cant be done if the flash is locked. Unfortunately replacing the part is the solution

    - Vaish

  • 0 in reply to Vaishnavi Ramachandran
    Prodigy 80 points

    Dear Ramachandran

    Thanks for reply

     It happened in two cases

    1.Unknowingly one of my friend Halted the Erase Operation

    2. The Supply to controller is gone while erasing

    so if i just program Flash Erase routine one time in FLASH SECTOR(which will not be erased & programed later) by taking necessary precautions before the corruption of passwords.

    will it erase my Flash if anything happens like i said above.

  • 0 in reply to SADGUNA RAO KURRA
    TI__Intellectual 1950 points

    Sadguna,

    The above mentioned conditions are valid cases where the passwords could get corrupted if an erase is interrupted.Please look into the following post that explains balanced sectoring in flash.

    Please look into the below post , this explains how sectors are balanced.

    http://e2e.ti.com/support/microcontrollers/tms320c2000_32-bit_real-time_mcus/f/171/t/111828.aspx#395926

    Let me know if you have any more questions

    -Vaish

  • 0 in reply to Vaishnavi Ramachandran
    Prodigy 80 points

    Vaish,

    I gone through the discussion but didn't get it exactly.

    Please clarify me one thing that If the Erase Operation on SECTORs (Except SECTORA which has CSM password Locations) is Interrupted will it cause any problem ?

    Is it possible to program the Procedure to run the Flash erase routine when csm is corrupted into OTP memory ?

    Regards,

    Guna

  • 0 in reply to SADGUNA RAO KURRA
    Prodigy 80 points

    Hi there,

    Please Clarify my above doubts.

    Thanks in Advance

    Guna