J-LINK did not found CPU (TMPA900) on own Board

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  • J-LINK did not found CPU (TMPA900) on own Board

    Hi,

    I have a J-Link (USB, JTAG) and want to connect it to a TMPA900 (ARM926EJ-S Core). As long as I use the base board from Glyn everything is fine, the device is found by J-Link. See picture JLink_pic1.
    Then I switched the CPU board to our own base board and no device is found. See second picture JLink_pic2.

    So we checked the connections and schematic but we did not find any error. The schematic of the JTAG connector is the same, the 10k resistance on pin 130 exists. All signals have contact from the 20 pin connector to the connector of the CPU board.

    The signal levels before connecting to J-Link seem to be ok. When J-Link try to connect there is one thing to be noticed: The RESET pin toggles and the TCK_RTN pin is zero the whole time.

    Right now I have no idea what could cause this behavior. Does anyone have a hint?

    Best regards.
    bpie
    Images

    • JLink_pic1.jpg

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    • JLink_pic2.jpg

      45.06 kB, 606×301, viewed 551 times

  • Hi,

    The reset pin toggles because J-Link is trying its best to get any chance to gain control over the device which also includes resetting it, if a regular connect does not work.
    No doubt that there *is* a difference between your board and the one from Glyn...
    Can you send/post your schematics?
    Feel free to send them to segger.com/support/technical-support/ (referring to this thread) if they are confidential.


    - Alex
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