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TMS320F28022: Debugging Issue

Marvn Arcangel
Genius 11615 points
Part Number: TMS320F28022
Other Parts Discussed in Thread: LAUNCHXL-F280049C, TMDSEMU200-U

Hi Team,

Would you kindly assist with the inquiry below?

A customer developed a custom board with the TMS320F28022PTT after programming a LAUNCHXL-F280049C. They encounter no issue programming the board, but they got a stuck-at-zeros faults when trying to test the connection between the CCS and the board through the LAUNCHXL on board XDS110. They have removed the shunts from J101 on the LAUNCHXL, They use a breakout board with the cable from J102 to the appropriate signals on my board. they placed the F28022 into Wait Mode by pulling GPIO37 high before powering it on. After that they applied power, then removed the pull up on GPIO37, and tried manually pulling XRS low with a jumper. After this they attached the LAUNCHXL via J102, already with power on and connected to CCS. the target configuration set to F28022 on CCS for XDS110, with cJTAG and SWD off. nTRST  is registering as ~2.9 V with a 10 kR pulldown, and XRS is high, but  the test connection always fails with the scan path stuck-at-zero issues. 

here is the link to the pin out reference: https://software-dl.ti.com/ccs/esd/documents/xdsdebugprobes/emu_jtag_connectors.html

I hope you can help. Let me know if you need more information.

Regards,

Marvin

  • 0
    TI__Guru* 95315 points

    Here is my understanding of the issue: 

    1. You are able to successfully connect/program the F280049. This tells us that the overall health (and specifically the JTAG circuitry) of the board is good.
    2. You removed the jumpers on J101 to isolate the F280049 and used the JTAG circuitry alone to connect to a custom F28022 board.

    Is the above correct?

    Marvn Arcangel said:
    After that they applied power, then removed the pull up on GPIO37, and tried manually pulling XRS low with a jumper.

    I presume the F28022 is a new device with a blank flash. If so, you can attempt to connect to the device in Wait-mode itself. No need to bring it out of Wait mode. Also, no need to manually reset the device, since there is an on-chip POR circuitry.

    Marvn Arcangel said:
    nTRST  is registering as ~2.9 V with a 10 kR pulldown,

    -TRST should be normally low (in standalone functional mode), but this pin will be driven high when the JTAG debug probe tries to take control of the device (via CCS). Not sure why this is at 2.9v.

    Please provide the wiring diagram between J102 and F28022. I hope you have connected the grounds of the two boards together.

    Please refer to www.ti.com/lit/SPRACF0 for debug tips.

  • 0 in reply to Hareesh Janakiraman
    TI__Genius 11615 points

    Hi Hareesh,

    Good day and thanks for the response.

    you are correct, the jumpers on J101 are removed, and then use only an ARM 10 pin cable attached to J102 to debug, while supplying power to the board separately. From the 10-pin cable, three grounds are connected to the custom board ground, and the TMS, TCK, TDO, TDI, and nRESET signals to the appropriate pins on the F28022, as shown in the schematic. nRESET has a 10k pulldown on the board and is normally low, but upon connecting the debug cable it goes high. Key and VTRef are left unconnected.

    In addition, the JTAG lines may be more than 6 inches, but I would imagine that would affect signal integrity, and would not be responsible for the stuck at zero faults, is this a safe assumption to make?

    Regards,

    Marvin

  • 0 in reply to Marvn Arcangel
    TI__Guru* 95315 points

    You haven't provided the wiring diagram  between J102 and F28022.

    Marvn Arcangel said:
    but I would imagine that would affect signal integrity, and would not be responsible for the stuck at zero faults, is this a safe assumption to make?

    Yes.

  • 0 in reply to Hareesh Janakiraman
    TI__Guru* 95315 points

    I checked with the JTAG experts and received the following feedback: “The ‘XDS_RESET_OUT’ on the LaunchPad isn’t the same as -TRST signal and hence cannot be used to debug devices that need a -TRST signal”.

  • 0 in reply to Hareesh Janakiraman
    TI__Genius 11615 points

    Hi Hareesh,

    would the onboard XDS110 on the launchpad have a TRST signal on the chip itself making it possible to tap the pin with some fine gauge wire? If not will the programmer TMDSEMU200-U help?

     

  • 0 in reply to Marvn Arcangel
    TI__Guru* 95315 points
    Marvn Arcangel said:
    would the onboard XDS110 on the launchpad have a TRST signal on the chip itself making it possible to tap the pin with some fine gauge wire?

    No.

    Marvn Arcangel said:
    If not will the programmer TMDSEMU200-U help?

    Yes.