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TMS320F280049: DCSM and the DCSM GUI tool usage

Wayne Huang
Genius 15745 points
Part Number: TMS320F280049
Other Parts Discussed in Thread: C2000WARE

Dear Champs,

I am asking this for our customer.

The user is studying DCSM and the DCSM security GUI tool (syscfg) in

C:\TI\c2000\C2000Ware_3_03_00_00\driverlib\f28004x\examples\dcsm

and the app note

https://www.ti.com/lit/an/spracp8/spracp8.pdf?ts=1603968492747&ref_url=https%253A%252F%252Fwww.google.com%252F

Would you please help clarify?

1) Even with the GUI tool, it seems the user still needs input the two link pointers on GUI (for each zone) correctly (same and right) by themselves.

The GUI could not guarantee the link pointers are correct if the user wrongly inputs them.

Is it right?

2) In 3.13.1.6 Link Pointer and Zone Select

(P142 of TRM sprui33c, 

https://www.ti.com/lit/pdf/sprui33

)

It says, "....All OTP locations except link pointer locations are protected with ECC. Since the link pointer locations are not protected with ECC, three link pointers are provided that need to be programmed with the same value. The final value of the link pointer is resolved in hardware when a dummy read is done to all the link pointers by comparing all the three values (bit-wise voting logic)....."

What does that mean by the "three" link pointers?

In the GUI, it appears we have "two" link pointers in each zone - Current LINKPOINTER for BANK0 and BANK1.

3) If the user gets an F280049 IC from others and knows the DCSM passwords, can the user know which link pointer is currently used from the GUI given the OTP has been programmed by others?

4) If the user sets passwords but configures all RAM LSx and flash sectors as Unsecure. Can it be used somewhat like JTAG lock - JTAG cannot be connected without the password, but the codes can still be updated by wired (like CAN) external host without unlocking first because all the memory/flash are not secured?

(PS. I am aware that later F2838x has JTAG lock. But here, we just want a similar function.)

Wayne Huang

  • 0
    TI__Guru** 113915 points

    Hi Wayne,

    Thank you for using the Security tool. Please find below the answer to your query -

     

    1) Even with the GUI tool, it seems the user still needs input the two link pointers on GUI (for each zone) correctly (same and right) by themselves.

    The GUI could not guarantee the link pointers are correct if the user wrongly inputs them.

    Is it right?

    That is correct.

     

    It says, "....All OTP locations except link pointer locations are protected with ECC. Since the link pointer locations are not protected with ECC, three link pointers are provided that need to be programmed with the same value. The final value of the link pointer is resolved in hardware when a dummy read is done to all the link pointers by comparing all the three values (bit-wise voting logic)....."

    What does that mean by the "three" link pointers?

    In the GUI, it appears we have "two" link pointers in each zone - Current LINKPOINTER for BANK0 and BANK1.

    There are three link pointer location on OTP  but if you are using tool, you don't have to worry about that. It'll generate the same value for all three locations.

     3) If the user gets an F280049 IC from others and knows the DCSM passwords, can the user know which link pointer is currently used from the GUI given the OTP has been programmed by others?

    You can always read the link pointer value from the memory map register even though you don't have the passwords. With passwords, you can unlock the zone and read all three linkpointer values from USER OTP locations.

     

    4) If the user sets passwords but configures all RAM LSx and flash sectors as Unsecure. Can it be used somewhat like JTAG lock - JTAG cannot be connected without the password, but the codes can still be updated by wired (like CAN) external host without unlocking first because all the memory/flash are not secured?

    (PS. I am aware that later F2838x has JTAG lock. But here, we just want a similar function.)

    No, on this device JTAG access is blocked to secure RAM and Flash sectors only (no JTAGLOCK feature). So unless RAMs/Flash sectors are secure, there is no security for that. 

    Regards,

    Vivek Singh