J-LINK Minimum connection to TARGET

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  • Hi,

    Since Cortex-M supports SWD, the absolute minimum number of pins needed on the MCU side are:
    SWCLK
    SWDIO

    In addition to that J-Link needs:
    GND
    VTref => Target reference voltage (usually VCC) for buffers on J-Link, so it can output the correct high-level signals. Example: Your target interface operates at 3.3V, VTref needs to be 3.3V.

    So you need 2 signals to/from the CPU, GND and the target reference voltage.


    Best regards
    Alex
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