TMS320F28069: XDS110: is it possible to bypass VTREF?

j.seydoux

Part Number: TMS320F28069

Hello,

I'm working on a project based on a TMS320F28069. We use a tag-connect connection for debugging and thus don't have the VTREF signal on the JTAG link. We only have the following signals:

TDI
TDO
TMS
TCK
nTRST
GND

When connecting the XDS110 debug probe to our PCB, the debug probe raises an error saying that the PCB is not powered which is normal since the VREF signal is not connected to the PCB.

Is there any way to bypass the XDS110 VTREF signal (i.e. setting the configuration of the XDS110) to bypass target board power supply measurement and force the JTAG communication voltage level? If yes, how?

Thank you in advance for your help.

Best regards

over 5 years ago

0 Peter Galicki over 5 years ago

TI__Expert 8105 points

Hello,

Please start this debug by reading JTAG Debug Appnote (literature# SPRACF0), here is the link:

REgards,

Peter

0 j.seydoux over 5 years ago in reply to Peter Galicki

Intellectual 740 points

Hello Peter,

Thank you for the document but it clearly does not answer my question (or I missed something).

I am no trying to debug the debugger, I am only trying to know if it is possible not to use VTREF pin on the XDS110 or if this pin is mandatory for the XDS110 to work?

So, in other words, is that realistic to use a Tag-Connect connection with the XDS110 knowing that there is not enough signals on the Tag-Connect (6-pin) for the VTREF signal.

Thank you for your help.

Best regards

0 desouza over 5 years ago in reply to j.seydoux

TI__Guru**** 171309 points

Hi,

VTRef (or TVRef) is required for proper operation.

You can always hack your way and trick this signal by applying power directly to it through a current limiter resistor - do this at your own risk.

Keep in mind that, under these conditions, if there is absence of power on the target the Debug Probe will not flag it and any connection errors will be quite random.

Additional details at the XDS Target Connection Guide page at:

https://software-dl.ti.com/ccs/esd/documents/xdsdebugprobes/emu_xds_target_connection_guide.html

Regards,

Rafael

0 j.seydoux over 5 years ago in reply to desouza

Intellectual 740 points

Hello,

Thank you for your answer.

Regards.

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TMS320F28069: XDS110: is it possible to bypass VTREF?