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XDS100v3 and SWD

Juhis
Prodigy 220 points

Hi,

I have an Olimex XSD100v3 emulator and I have a problem connecting to Tiva microcontroller. I'm using Tiva launchpad and I have the same problem with our own board. I can connect to controller if I use JTAG connection and set the emulation mode to XDS100v2, but if I try to change the mode like it is described in Olimex guide (https://www.olimex.com/Products/DSP/Emulators/TMS320-XDS100-V3/resources/TMS320-XDS100v3_UM.pdf), namely Generate 1149.7 4-pin standard mode it won't connect but just complain:

 'SC_ERR_PATH_BROKEN'.

The JTAG IR and DR scan-paths cannot circulate bits, they may be broken.
An attempt to scan the JTAG scan-path has failed.
The target's JTAG scan-path appears to be broken
with a stuck-at-ones or stuck-at-zero fault.

The question is should the mode described in Olimex pdf work? Will I be able to use SWD (2 wire) in XDS100v2 mode? If yes what I'm doing wrong? And is it at all possible to use 2 wire mode with ccs5.5 and XDS100v3?

BR

JHi

  • 0
    TI__Intellectual 2515 points

    1149.7 cJTAG is not the same as ARM's SWD.  Both are 2-wire debug connections that work over existing JTAG pins, but they use completely different protocols for transferring data and are not compatible.

    The Tiva supports SWD connections, but not cJTAG.  The XDS100v3 supports cJTAG, but not SWD.  You cannot use the XDS100v3 in 2-wire mode with the Tiva.

    You will have to use the 1149.1 4-wire JTAG mode to debug the Tiva with an XDS100v3.

  • 0 in reply to Edward Fewell
    Prodigy 220 points

    Thanks for the answer, but what does then this mean on XDS100v3 wiki page:

    Support for ARM Ltd's Single Wire Output (SWO).

    If XDS100v3 supports SWO why it doesn't support SWD? I thought SWD and SWO would be tied together.

    And maybe a stupid beginner question but  what is the pin difference between cJTAG and normal JTAG connection?

    BR

    JHi

  • 0 in reply to Juhis
    TI__Intellectual 2515 points

    It appears that during XDS100v3 development there was a plan to allow SWO trace, possibly switching the target to SWD mode without supporting full SWD debug.  That wiki entry is an artifact from the original plan, but it was never implemented in the FPGA or the CCS software.  So the entry is incorrect. I will remove it when I get a chance.  The XDS100v3 does not support SWO at this time.

    Basically cJTAG disables the TDI and TDO pins and only uses the TCK and TMS pins for communications (TMS becomes bi-directional in cJTAG).