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AM623: AM623, 10-pin JTAG adaptor and TRSTN

Part Number: AM623

I'm trying to work out what to do with the TRSTN pin on the AM623 if I use a10-pin JTAG adaptor on the board. I know I need to pull it low but will JTAG still work using the 10-pin connector?

  • We normally recommend a 14-pin connector. I'm not sure which 10-pin connector you plan to use, so not able to comment on it.

    We also recommend a pull-down on the TRSTn signal to ensure the TAP controller never receives any spurious commands during normal operation.  Therefore, the TRSTn signal must be connected to the debugger and must be driven high when communicating with device via JTAG.

    Regards,
    Paul

  • Hi Paul

    The 10-pin is an option on the XDS110. The 14-pin from the XDS110 doesn't seem to have a nRESET line though, isn't this required?

    Thanks

    Paul

  • I do not recall see a 10-pin connector implementation be used with Sitara processors. I suspect the 10-pin connector definition is used with devices that do not require TRSTn to be sourced by the debugger. 

    The answer to your question is "Yes". As mentioned in my previous reply, TRSTn is required. The debugger must drive the TRSTn signal high to send commands via JTAG.

    Use the 14-pin connector definition on your PCB.

    Regards,
    Paul

  • The 14-pin connector doesn't have the nRESET line - is this required to be connected to the processor when using JTAG? I'm looking at XDS110 Debug Probe datasheet for the pin-outs

  • The nRESET signal is an optional system reset that allows the debugger to reset the entire system.

    Regards,
    Paul