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TMS320F280049: code can't run after reset with password written to the device

Howard Zou
Genius 12365 points
Part Number: TMS320F280049


Hi,

my customer write their application code at 0x80000-0x83000, and they grab these sectors to zone1, and then write password in OTP to protect it.

That should mean, all the application code are in secured memory.

Then they load their code to F280049 launchpad, and then unconnect the MCU, the code could not run correctly.

With the same code and without password writen, the code could run well(for example, the LED will blink).

And then we try to debug the code with CCS:

1. Change the BOOTMODE pin to "wait boot",

2. Power cycle the board

3. Connect to CCS

4. Open flash plug-in GUI

5. Enter correct password for Zone1 and unlock the zone.

6.

(This picture should mean that the code is stopped somewhere in BootROM code).

7. We tried to set breakpoint at code_start but it could not stop there so we could not debug the code to find what's wrong

So we are not able to debug the device with CCS.

And we also tried modify our application code, at CommonStartPointer (shown in the picture above), we add some code to unlock the device. Then load the code to F280049 launchpad and it could run well.

Then we guess the reason why the code is not running correctly is that some code cause password protection and trigger reset.

But we find it not acceptable since all the code reside in the secured memory. Could you please suggest some reason? 

And we also tried to read the flash memory with CCS memory browser, and find that all the result are 0x00. But in fact only 0x80000-0x83000 are protected by Zone1 password, why the other unprotected flash also return 0x00 when read it?

  • 0
    TI__Guru** 115881 points

    Zou,

    Does application uses any of the LSx RAM ? Please note that 'b11 value for GRABRAM and GRABSECT is invalid and it'll make the memory in-accessible if any of the zone is locked. In this case you are locking the Zone1 with programming the password but did not programed the GRABRAM so all the RAMs will be inaccessible. Same thing is happing with the flash which you have not grabbed. Since it has not been grabbed and Zone1 is locked, it is showing value 0x0. Please refer "Table 3-16. RAM/Flash Status" in TRM for more detail on this.

    I would recommend using the security tool for the configuration. That takes care of all such issues. You can refer this appnote which provides info on how to use the security tool.

    Regards,

    Vivek Singh

  • 0 in reply to Vivek Singh
    TI__Genius 12365 points

    Vivek,

    let's take flash as example.

    FLASH BANK0 has sector 0-15, flash bank 1 also has sector 0-15.

    Zone 1 can grab either bank 0 or bank 1.

    For example, we can grab bank0 sector 15& band 1 sector 0 to zone1, correct?

    Then what we do in our code is:

    we grab BANK0 sector 0,1,2 to zone1.

    For the rest of BANK0 and whole BANK1, neither zone1 or zone2 grab it since all grabsect are 0x11.

    So it means that only BANK0 sector0,1,2 belongs to zone1 and is protected by the password.

    Which should be okay in my understanding.

  • +1 in reply to Howard Zou
    TI__Guru** 115881 points
    Howard Zou said:
    For example, we can grab bank0 sector 15& band 1 sector 0 to zone1, correct?

    This is correct.

    Howard Zou said:

    For the rest of BANK0 and whole BANK1, neither zone1 or zone2 grab it since all grabsect are 0x11.

    So it means that only BANK0 sector0,1,2 belongs to zone1 and is protected by the password.

    Which should be okay in my understanding.

    No, this is not correct. On this device, 'b11 does not mean it's unsecure bit it's invalid. As I mentioned in my earlier post, Please refer "Table 3-16. RAM/Flash Status" in TRM for more detail on this. Below is snapshot of the same.

    You can see value 11 has note and in the note it is mentioned that these values are only applicable if zone is secure. Since you have zone1 locked, you need to program these value to 'b10 for all the sector which are not grabbed by Zone1. Hope this is clear. If you use the security tool, you'll see the correct configuration.

    Regards,

    Vivek Singh