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TMS320F28379S: XRS\ constantly resetting,TRSTn\ always low

don morgan
Intellectual 850 points

Part Number: TMS320F28379S

I have a board, really just a second generation of a working design. Only minor changes and board size.

The problem is that the XRS\ pin pulses low every 15ms (25MHz xtal) and the TRST\ is always low (processor driven).

Any thoughts on what I have wrong? I wired up the jtag connection myself and have now checked it 9 times.  here is the error message:

Error connecting to the target:
(Error -2131 @ 0x0)
Unable to access device register. Reset the device, and retry the operation. If error persists, confirm configuration, power-cycle the board, and/or try more reliable JTAG settings (e.g. lower TCLK).
(Emulation package 9.2.1.00046)

Thanks,

Don

  • 0
    TI__Guru* 95315 points

    Don,

    On a fresh device with an erased flash, the watchdog counter will keep overflowing and resetting the device. Is that the case here? What is the width of the reset pulse?

    -TRST is an input pin, with a weak internal pull-down. Our datasheet recommends an external PD as well, which your board probably has.

  • 0 in reply to Hareesh Janakiraman
    Intellectual 850 points

    Yes, the board is fresh with blank flash. I also have the two boot pins pulled high.

    I do have a pull down on board and I would say the pulse is (negative) about 120us wide.

    Thanks,

    Don

  • 0 in reply to don morgan
    Intellectual 850 points

    I have now removed the pull-ups on the boot pins and the pulsing on the XRS\ pin stopped. it is high at 3.3V, now. But I still can't connect with the JTAG XDS110.

    Thanks,

    Don

  • 0 in reply to Hareesh Janakiraman
    Intellectual 850 points

    OK, as of now I have tried a number of different boot settings. The probe passes connection test but fails produces a very buggy emulation session.

    It will pass the connection test with a lower frequency, once it said it erased the flash and loaded the program but failed to run the session.

    When I try, I usually get one of these:

    C28xx_CPU1: GEL Output:
    Memory Map Initialization Complete
    C28xx_CPU1: Error: (Error -1044 @ 0x0) The debug probe reported an error. Confirm debug probe configuration and connections, reset the debug probe, and retry the operation. (Emulation package 9.2.1.00046)
    C28xx_CPU1: Error: (Error -1135 @ 0x83A53) The debug probe reported an error. Confirm debug probe configuration and connections, reset the debug probe, and retry the operation. (Emulation package 9.2.1.00046)
    C28xx_CPU1: Unable to determine target status after 20 attempts
    C28xx_CPU1: Failed to remove the debug state from the target before disconnecting. There may still be breakpoint op-codes embedded in program memory. It is recommended that you reset the emulator before you connect and reload your program before you continue debugging

    (Error -1050 @ 0x0)
    Internal error: Invalid parameter passed to function. Restart the application. If error persists, please report the error.
    (Emulation package 9.2.1.00046)

    I get farthest if I am holding the flat cable between the board and the debugger.

    Thanks,

    Don

  • 0 in reply to don morgan
    TI__Guru* 95315 points

    Does your old design work with the same debug probe (XDS110)? If so, there is something wrong with your new board. Can you share the schematics of the board privately?

     

    I do have a pull down on board 

    Pull-down on which pin?

     

    I would say the pulse is (negative) about 120us wide

    Please attach a scope capture.

     

    Did SPRACF0 help you at all?

  • 0 in reply to Hareesh Janakiraman
    Intellectual 850 points

    I had already gotten rid of the toggling on XRS\ when I got the pdf you mention.

    The two boot pins were pulled high originally and now I have them each pulled low through 2.2k resistors.

    you should find the schematic attached, the schematic will show the above mentioned pins pulled high, they are now pulled low.

    All the power supplies are within margins.

    encoder_20201214.pdf

  • 0 in reply to don morgan
    Intellectual 850 points

    In addition, here is a picture of the board and connection to the debugger.

  • 0 in reply to don morgan
    TI__Guru* 95315 points

    Don,

    If the same setup works fine with your previous design, clearly something is wrong with the current board or the JTAG connection. This issue likely warrants hands-on debug. I am afraid I can't help further.

  • 0 in reply to Hareesh Janakiraman
    TI__Guru* 95315 points

    One thing to check: The -TRST pin will be driven high by the debug probe when CCS attempts to connect to the device.  Please check the -TRST connection since you say it is always low.

  • 0 in reply to Hareesh Janakiraman
    Intellectual 850 points

    Yes, it toggles when it is supposed to, it is low when it is dormant.

    I did find that pressing on a pin (pin49-tms) would get it to work, if I held a probe there for long enough I could get it to erase flash, program flash and start the emulation and if I stopped the emulation, it stopped at the correct place and displayed the correct data in memory.

    So, I had the pin re-soldered but that didn't fix it. However, if I pressed on it, I could get it to work.

    This is driving me nuts.

    Thanks,

    Don

  • 0 in reply to don morgan
    Guru 92251 points

    don morgan said:
    Yes, it toggles when it is supposed to, it is low when it is dormant.

    Can you try changing the R47 pull-down on TRSTn from 2.2K to 10K?

    I have seen other posts which mention the XDS110 has trouble overcoming the C28xx recommended 2.2K pull-down on the TRSTn pin. E.g. see CCS/TMDSEMU110-U: XDS110 not working, but my XDS100v2 works fine

  • 0 in reply to Hareesh Janakiraman
    Intellectual 850 points

    I had all the pins on the MCU re-soldered and the 2.2k on the trst\ pin changed to 10k and it works

  • 0 in reply to don morgan
    TI__Guru* 95315 points

    Don,

    Glad the issue is resolved. Reading through the thread, I am not clear if it was a soldering issue or the PD resistor. Now that you have eliminated (hopefully) soldering as a cause, could you please restore the 2.2k resistor and verify if everything works? On a different note, did you capture the -TRST waveform with 2.2K and 10K resistors?