[SOLVED] Cannot connect to target. "CPU-TAP not found in JTAG chain"

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  • [SOLVED] Cannot connect to target. "CPU-TAP not found in JTAG chain"

    When I tried to connect our custom board with chipset MCIMX6D7CZK08AD, I am getting the following error.

    Hardware List:
    MCIMX6D7CZK08AD board with 10pin TAG CONNECT pattern
    Segger 10-Pin Needle Adapter
    Segger J-Link PLUS Compact

    We have verified that the pin connections on the hardware seem correct.

    I also attached the log which was capture by JLink Control Panel.

    Could you please take a look and let me know how to fix the issue?

    TD764 009:494.940 JLINK_Connect()
    TD764 009:497.689 TotalIRLen = ?, IRPrint = 0x..000000000000000004A60001
    TD764 009:498.534 Failed to identify target. Resetting via Reset pin and trying again.
    TD764 009:651.950 TotalIRLen = 5, IRPrint = 0x01
    TD764 009:652.810 JTAG chain detection found 1 devices:
    TD764 009:653.041 #0 Id: 0x2191E01D, IRLen: 05, Unknown device
    TD764 009:653.064
    ***** Error:
    TD764 009:653.077 CPU-TAP not found in JTAG chain
    TD764 009:653.291 Connect failed. Resetting via Reset pin and trying again.
    TD764 009:716.779 TotalIRLen = 5, IRPrint = 0x01
    TD764 009:717.421 JTAG chain detection found 1 devices:
    TD764 009:717.573 #0 Id: 0x2191E01D, IRLen: 05, Unknown device
    TD764 009:717.640
    ***** Error:
    TD764 009:717.647 CPU-TAP not found in JTAG chain
    TD764 009:717.656 - 222.715ms returns 0xFFFFFEFB
    TD694 524:514.144 JLINK_GetHWInfo(...)
    TD694 524:514.560 - 0.380ms returns 0
    TD5B0 525:015.104 JLINK_GetHWInfo(...)

    TD5B0 525:015.392 - 0.295ms returns 0

    Thank you.
    Files

    The post was edited 3 times, last by softwareDev ().

  • IRLen = 5 is not a valid IRLen for a DAP-TAP (the JTAG TAP used to access the ARM Cortex core).
    It should be IRLen = 4.

    I see 2 possible reasons for this:
    1) Signal quality issue so that some bit(s) are not sampled correctly and this leads to a wrong ID / IRLen to be detected
    2) The chip is in some kind of special mode (boundary scan, ...) where not the DAP-TAP (IRLen = 4) is visible on the JTAG chain but another TAP (IRLen = 5)
    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.

  • Thank you for the response. It looks like I can try the second option first.

    Do you have a procedure to change IRLen value by changing boundary scan mode to some other mode?

    I found the procedure to change to the boundary scan mode with Lauterbach JTAG debugger:
    nxp.com/docs/en/application-note/AN12919.pdf

    Do you have something similar for Segger J-Link?

    Please let me know.

    Thank you.

    The post was edited 1 time, last by softwareDev ().

  • The device should not and is not in boundary scan mode by default. You either set it via fuses or boot pins.
    Last but not least it was only a wild guess from my side.

    You should know what mode you configured your device into.
    Also, did you make sure that there is no application booting that interferes with debugging?
    E.g. a Linux that power-off debug clocks, remaps debug pins to GPIO, …
    Inhibiting the boot of your application by selecting a different boot source is something you should consider.
    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.

  • I checked with a brand new board without any firmware (no eFuses set), but I am still getting same result. JTAG_MOD is not set high.

    Connecting to target via JTAG
    TotalIRLen = 5, IRPrint = 0x01
    JTAG chain detection found 1 devices:
    #0 Id: 0x2191E01D, IRLen: 05, Unknown device
    Connect failed. Resetting via Reset pin and trying again.
    TotalIRLen = 5, IRPrint = 0x01
    JTAG chain detection found 1 devices:
    #0 Id: 0x2191E01D, IRLen: 05, Unknown device

    The post was edited 1 time, last by softwareDev ().