[SOLVED] Unlocking MKV30F64VFM10 using J-Link using known backdoor key

This site uses cookies. By continuing to browse this site, you are agreeing to our Cookie Policy.

  • [SOLVED] Unlocking MKV30F64VFM10 using J-Link using known backdoor key

    Hi forum, I bricked my KV30's via it's security bits during our effort to experiment with recovering from a mass erase failure.

    0x40C, FSEC, is set to 0xA5. This means that:
    • MCU Security status is secure
    • NXP factory access denied
    • Mass erase is disabled
    • Backdoor key access enabled
    All attempts to connect or unlock our KV30 has failed. In JFlash, connections have an error stating "Could not find core in coresight setup". Connections in JLink Commander state "readout protection is set and mass erase is disabled". The unlock fails with "Unlock via debug port is disabled. Unlock failed."

    This indicates the unit is largely bricked, but we do know 0x400-0x407, the backdoor key. How can I use this backdoor key to regain access to the KV30 using JLink? On the forums it recommends connecting to the device and then using the write commands to verify the backdoor key, but my connections fail right away. Is the unit salvageable or would it be a better idea to just replace the chip? Thanks.

  • I do not specifically know the KV30 into much detail but have worked on many of the various Kinetis flash algorithms for J-Link.

    For all Kinetis I have encountered, the debug interface does not provide a way to get the backdoor key into the chip. The manual said that the user is responsible to implement a way of receiving the key (e.g. via UART, SPI, …) and then the user application must copy it into the backdoor key comparison registers, to actually trigfer the temporary unlock.

    If the application does not provide such a functionality, knowing the backdoor key is unfortunately useless.

    Pretty sure your chip is bricked forever.
    Please read the forum rules before posting.

    Keep in mind, this is *not* a support forum.
    Our engineers will try to answer your questions between their projects if possible but this can be delayed by longer periods of time.
    Should you be entitled to support you can contact us via our support system: segger.com/ticket/
    Or you can contact us via e-mail.