[SOLVED] J-Trace compatible SWD+Trace interface

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  • [SOLVED] J-Trace compatible SWD+Trace interface

    I have purchased the J-Trace PRO for Cortex-M processors. My development board has a pinout for SWD ; i.e. section 18.1.2 of the J-Trace User Guide (UM08001). The header on my boards is a 20 way Insulation Displacement Connector (IDC) keyed box header (2.54mm male). I need to retain this header and it's pinout to remain compatible with existing deployment tools without the need of adapters; i.e. continued support for the ST-Link. I want to add trace lines to this header (I assume using pins 14/16/18/20) so I can use the trace feature of the J-Trace. When using the J-Trace trace header I expect to need an adapter. Can you recommend a pinout which meets my requirements, and recommend an adapter which converts my existing header to the 19-pin JTAG/SWD and Trace connector (0.05“ / 1.27mm) on the J-Trace PRO.

  • Hello,

    Thank you for your inquiry.
    We do not recommend routing the trace signals to the 2.54 mm header. Trace signals are not specified by Arm for that type of header and most probes expect there to be ground. Some third party probes might break down if other signals are routed there so we can't recommend this approach.
    Here is the official pin out:
    segger.com/products/debug-prob…gy/interface-description/

    For tracing we recommend using only the 1.27mm 19 pin header. To keep that compatible to the larger 2.54 header type you can use the following adapter:
    segger.com/products/debug-prob…/19-pin-cortex-m-adapter/


    That way you do not risk damage to your debug probes and stay within specification with your board. Also you save some space on the board with the smaller header so we generally recommend using that where possible.


    Best regards,

    Nino
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