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TMS570LC4357: TMS570LC4357 flash protection mechanism

Peggy Chiu
Prodigy 10 points

Part Number: TMS570LC4357

Dear sir, 

I am researching some external resources that I could use for the TMS570LC4357 L2 flash (0x00000000 to 0x0x003FFFFF) protection.  I know there is MPU which software can program to protect the region, but I would like to investigate if similar protection can be done in hardware?

Secondly, in browsing the support forum, I saw a post indicating the TMS570LC4357 flash at 0xF000_0000 to 0xF00C_1FFF, is OTP which can only be programmed one time?   I just want to get a confirmation if that is true statement?

Appreciate if you can help me!  Thanks!

Peggy

  • 0
    TI__Mastermind 26930 points

    Hi Peggy,

    Apologies for the late response. I am looping in the expert to look into this.

    Best Regards,

    Delaney

  • 0 in reply to Delaney Woodward
    Prodigy 10 points

    Any feedback is appreciated!!

  • 0 in reply to Peggy Chiu
    TI__Guru* 80596 points

    Hi Peggy,

    Flash Write Protection via FBPROT Registers

    • The Flash Memory Wrapper (FMW) includes Flash Bank Protection Registers that can be configured to write-protect individual flash sectors at a hardware level.

    If we program this register that will protect us from writing into FBSE register (sector enable bits), without writing into these sectors enable bits not possible to program the flash.

    Peggy Chiu said:
    Secondly, in browsing the support forum, I saw a post indicating the TMS570LC4357 flash at 0xF000_0000 to 0xF00C_1FFF, is OTP which can only be programmed one time?   I just want to get a confirmation if that is true statement?

    Yes, the flash region at 0xF000_0000 – 0xF00C_1FFF on the TMS570LC4357 is indeed OTP (One-Time Programmable) memory.

    Key characteristics of this OTP region:

    • Once programmed (bits written from 1→0), they cannot be erased or reprogrammed. This is a fundamental property of the OTP flash technology used.
    • This region typically holds device configuration, security keys, trimming data, and user-defined permanent settings.

    --
    Thanks & regards,
    Jagadish.

  • 0 in reply to jagadish gundavarapu
    Prodigy 10 points

    Jagadish,

    Really appreciate the feedback.

    Regards to the flash write protection, thanks for the FBPROT register information.  That is the functionality that we were looking for.  But, instead of software program the FBPROT register, do you know if there is processor pin that can be toggled to enable or disable the write protection?

    Thanks

    Peggy 

  • 0 in reply to Peggy Chiu
    TI__Guru* 80596 points

    Hi Peggy,

    These are flash related protection methods that are available in this device.

    1. Program FBPROT Early in Boot (Before Untrusted Code Runs)

    • Configure FBPROT in your early boot code (e.g., reset handler / startup assembly), before any application or OS code executes.
    • This is the closest equivalent to a "hardware" protection since it is set before any potentially malicious or errant code can run.

    2. Use the JTAG locking

    • The TMS570LC4357 supports JTAG locking, which can prevent external debug access from modifying flash — this is a one-time hardware-level security measure.

    You can find JTAG locking and unlocking procedure in below links:

    Hercules AJSM Unlock (Rev. A)

    (+) [FAQ] TMS570LS3137: AJSM Locking and Unlocking procedure for Hercules Controllers - Arm-based microcontrollers forum - Arm-based microcontrollers - TI E2E support forums

    3. OTP Region for Permanent Settings

    • As discussed previously, the OTP region (0xF000_0000 – 0xF00C_1FFF) is inherently hardware-protected by its one-time-programmable nature — no pin or register can re-enable writes once programmed.

    --
    Thanks & regards,
    Jagadish.