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TMS320F28388S: Microcontroller Auto Reset issue

Ehsan Habib
Prodigy 20 points
Part Number: TMS320F28388S
Other Parts Discussed in Thread: LP-XDS110, CCSTUDIO

Hi, I have a board that we designed with TMS320F28388S Microcontroller. I am powering it up with 3.3 Volts, and forgot to add the 1.2 Volt, as i am more familiar with the new C2000 Mcu's, which has internal VREG to convert 3.3 to 1.2 Volts. So i made a small LDO board that use to generate 1.2 Volts and supply it to the MCU 1.2 Volt core. 

But the microcontroller is not getting detected by the MCU. When i probed the MCU reset pin, i found out it getting resetted after 14.6mS and for 46uS(keep low for 46uS and then goes high,but after 14 mS again goes low for 46uS). 

I have attcahed the circuit, please review it, and let me know the possible reasons. Redefined.pdf

I am using internal crystal, no external crystal onboard. 

  • 0
    TI__Mastermind 21140 points

    Hi Ehsan,

    The periodic resets on an unprogrammed device are expected due to the watchdog. I looked at your schematic, and I think your problem actually has to do with the JTAG header. You may need to use the 14-pin TI JTAG header, since that will allow you to connect TRST to your JTAG debug probe. Also, when a JTAG debug probe issues a reset to a C2000 device, it does drive the XRSn pin to do so, instead it writes to an internal register that will reset the device. For this reason, it is unnecessary to connect the XRS pin to your JTAG probe.

    I recommend that you take a look at this article, the connections that you will need from your F28388S board to your debug probe are TDI, TDO, TMS, TCK, TRST, GND, and 3V3 (VDDIO).

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

    Best Regards,

    Ben Collier

  • +1 in reply to Benjamin Collier
    Prodigy 20 points

    Hi Ben, I am using LP-XDS110 which has 10 pin debugger connector, the same i am using in my designed board also. Can i use LP-XDS110 for TMS320F28388S ? with 10 Pin Debug connector ?

    When i try to detect the MCU through CCS studio i get the following error using XDS110.

    The value is '-233' (0xffffff17).
    The title is 'SC_ERR_PATH_BROKEN'.

    The explanation is:
    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.

  • 0 in reply to Benjamin Collier
    Prodigy 20 points

    Hi Benjamin, I have solved the issue by connecting Trstn. As i am more familiar with the new devices of c2000, like P65 series, i didn't consider TRSTN for JTAG. 

    As i have both LP-XDS110 & XDS110 , I have used XDS110 to program the device.

    Can you confirm LP-XDS110 have TRSTN or not ?

  • 0 in reply to Ehsan Habib
    Prodigy 20 points

    Hi Benjamin, I can detect the MCU now with XDS110 debugger, But when i try to code it with a Example code from CCSTUDIO its shows error, and asks me to check the connections. 

    I am unable to code it from CCSTUDIO or from MATLAB. 

  • 0 in reply to Ehsan Habib
    TI__Mastermind 21140 points

    Hi Ehsan,

    I don't think our launchpad XDS110s have TRST exposed on a header pin. 

    When you see this error message, could you try power cycling your XDS110, probably by disconnecting it then reconnecting to your PC? 

    Best Regards,

    Ben Collier

  • 0 in reply to Benjamin Collier
    Prodigy 20 points

    Hi Benjamin, I am using XDS110 with TRST pin. I can detect the microcontroller using CCS, but when i try to flash it with any code, the "Error Connecting to the Target" still there. Please note i am using Internal crystal, I don't have any external crystal connected. Please help me find the possible issues. Please look at the circuit once again. 

    And as this thread was started with a different problem, should i start a new thread ? or we should continue here ?

  • +1 in reply to Ehsan Habib
    TI__Mastermind 21140 points

    Hi Ehsan,

    Do you have a custom 10-Pin JTAG header? I am having a difficult time understanding how the signals from your board are connected to the debug probe. Are you 100% sure that TDI, TDO, TMS, TCK, GND, and 3V3 are connected correctly?

    Also, you are using the standalone XDS110? How are you connecting TRSTn to your device? Did you solder some connection to R11? 

    Best Regards,

    Ben Collier

  • 0 in reply to Benjamin Collier
    Prodigy 20 points

    Hi Benjamin, All the connections were perfect. I had to change the MCU, i have used a new one, Now its working perfectly. Thanks for all your support.

    Yes, i had to connect a wire for the TRSTN with R11 .