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Code protection for F28069 device stops execution of code in flash

Johannes Wolkerstorfer
Prodigy 20 points


I have the following difficulty activating the CSM-password in a F28069 Control Stick:

Whenever, the CSM is activated (in my understanding the following suffices to activate the CSM: Set  CSM_RSVD and CSM_PWL locations in flash sector A:

  • "CSM_RSVD : origin = 0x3F7F80, length = 0x000076" are set to 0x0000,0x0000; 
  • "CSM_PWL_P0 : origin = 0x3F7FF8, length = 0x000008" are set to the 128-bit password), 

the following effects show up:

  • The software stored in Sector A is not executed anymore
  • It is extremely difficult to get a JTAG connection (e.g. for erasing sector A and thus removing the CSM protection)

This behavior shows up by activating the CSM protection in two different ways:

  1. Program flash sector A with CSM_RSVD= 0x0000, 0x0000, and   CSM_PWL_P0 = pwd0, ....
    1. by linking F2806x_CSMPasswords.asm with a non-all-FFFF key
  2. Program flash sector A without CSM (CSM_RSVD=0xffff,0xffff,... and CSM_PWL_P0=  0xffff,0xffff,...) and
    1.  Program the CSM password later interactively with CCSV4 

It is interesting that the software works fine when 2.) is executed but after doing 2a) the device does not execute the software anymore. Even when CSM_RSVD=0xffff,0xffff and just the password  CSM_PWL_P0 is set, the code (which is also in sector A) is not executed anymore.

I verified in all cases that the start instruction at "BEGIN : origin = 0x3F7FF6, length = 0x000002" is "LB _c_int00".

Any ideas?

Kind regards,

Johannes Wolkerstorfer, xFace.at, Austria.

  • 0
    Prodigy 20 points

    Short update: I tried the same on the "F2808 Experimenter Kit" which is very similar to F28069: It also has a XDS100v1 JTAG emulator on board and the F2808 has an identical CSM mechanism. On F2808, the CSM protection works absolutely fine:

    • JTAG can connect without any difficulty when the CSM password is set
      • When CSM is activated protected memory shows up as "0x0000"
    • User application programmed to Sector A is executed -- even when the CSM is activated.

    I tried two alternative approaches to activate the CSM of F2808:

    1. Compile and link CSM_RSVD and CSM_PWL
    2. Set CSM password interactively with CCSv4 after programming sector A without a CSM password

    Both methods worked fine. I also used the same 128-bit key as for F28069.

    So it seems to me that F28069 has troubles to activate the CSM. At least the device I am using.

     

    regards,

    Johannes.

  • 0 in reply to Johannes Wolkerstorfer
    TI__Guru 55700 points

    Johannes,

    Hope you got your problem resolved. If not ,your problem looks similar to one of the post i replied. Please try the suggestion made in that post.

    http://e2e.ti.com/support/microcontrollers/tms320c2000_32-bit_real-time_mcus/f/171/t/136391.aspx

    Regards,

    Manoj