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TMS320F28335: Connectivity issues and MCU overheat

Francesco Paparella
Prodigy 60 points
Part Number: TMS320F28335


Hello,

I am programming a TMS320F28335 and right now I have some connectivity issues with the MCU.  The MCU is part of the experimental development kit provided by TI.

When I am trying to deploy the code on the board through the USB port (either in CCS or Embedded Coder), I get the following error:

C28xx: Failed CPU Reset: (Error -1137 @ 0x6) Device is held in reset. Take the device out of reset, and retry the operation. (Emulation package 9.3.0.00032)  

Also, the MCU overheats quickly once I plug in the USB cable - too hot to touch it after few seconds.

Notes:

  • Jumper in J9 connected and the JTAG DR Integrity scan-test has succeeded.
  • The 5 V and 3.3 V pins on the docking station have the correct potential.
  • The LD1 on the control board dims lightly - not bright as the power led on the docking station. The Vout_1 of U2 component on the control board is 2.4 V instead of 3.3 V (I measured the voltage on L19). The Vout_2 of U2 component seems to be correct - the voltage measured on L20 is 1.8 V.
  • All boot pins GPIOs 84-87 are on ON position.
  • SW1 is in OFF position.

Any idea what the problem can be?

thanks

Fra

  • 0
    TI__Guru* 80720 points

    Francesco,

    Thanks for contacting the TI E2E.  From your description(device is hot, 3.3V supply is capped at 2.4V) I suspect that the TMS320F28335 MCU is damaged and there is a short from power to ground(likely though the ESD guard ring) based on a potential overvoltage event. 

    I think the easiest course of action would be to purchase a new F28335 control CARD.

    Best,

    Matthew

  • 0
    Prodigy 60 points

    Hello Matthew, 

    thanks for the reply,

    Do you know what are the common reasons for the overvoltage event? When the event happened, I was connected to the PC through the USB and I was testing the control board like this:

    • I had only a potentiometer (max R = 10 kOhm) connected the 3.3 V and GND header pins on the docking station and Vout to a ADC channel.
    • GPIO48 (configured as output in Simulink) was back-looped with a wire to GPIO9 (configured as input in Simulink) in order to debug my program. From the manual, I see that GPIO9 can be SCI-B transmit data, while GPIO48 seems to be ok to use. Was this connection unsafe?

    Before damaging the MCU, it happened that the MCU got blocked and I unblocked by grounding all the booting pins (as you suggested in another post). I am a bit confused on how to work with these MCUs...is there any safe practice I need to follow in order to avoid these problems in the future?

    thanks
    Fra

  • 0 in reply to Francesco Paparella
    TI__Guru* 80720 points

    Francesco,

    Typically there is an overdrive event on one or multiple GPIOs, sometimes our devices get connected directly to a 5V TTL device, which after some time will destroy the ESD protection diode on the GPIO and cause the short.  Other times it can be simple ESD from handling w/o being properly grounded or carrying an unused board outside an ESD bag.  This is less common after a device is mounted to a PCB, but can still happen.

    From your description of connections those should have been OK.  If the board has been in use by others prior to you that could also explain it.

    The flash blocking is unrelated, but can happen with power interruption to the board during programming.

    Best,

    Matthew