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Is there a correct sequence for powering up and programming a blank TM4C123GH6PM chip?

mhj555
Prodigy 50 points
Other Parts Discussed in Thread: TM4C123GH6PM

I recently had a circuit board made with a TM4C123GH6PM on it.  When I apply power, the current on the power supply approaches 1 Amp.  The TM4C123GH6PM is powered off a 3.3V linear regulator.  I am trying to apply 5V to the input of the regulator, but as soon as it gets close to about 2.5V, the current shoots up and the  TM4C123GH6PM gets hot.

My plan was to power it up, then connect a JTAG and program it.  I've removed mostly everything else from the board that might cause problems.

What am I doing wrong?  Should the /RESET or other pins be held at a certain state while the chip is blank?

  • 0
    Guru 27665 points
    Check your power supply connections. That's what I'd expect if you had something mis-wired.

    Robert
  • 0
    TI__Guru**** 244400 points
    Hello mhj555,

    Schematics for review as well?

    Regards
    Amit
  • 0 in reply to Robert Adsett
    Prodigy 50 points
    Problem solved - I was powering VDDC with the 3.3V supply. Now I'll have to somehow lift the pins, attach capacitors and connect them together.
    They should really name those pins something else.
  • 0 in reply to mhj555
    TI__Guru**** 244400 points
    Hello Mhj555,

    My main concern would be damage to the uC itself right now. The naming has been the same for a generation of LM3S and TM4C products, but in some retrospect I may agree with you. However changing the names is not possible at this time. It would require changes to almost every design collateral.

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Guru 117855 points

    Amit Ashara said:
    My main concern would be damage to the uC itself right now

    While our small tech group has avoided your plight - a small number of clients have not.    And - just as vendor's Amit suggests - most always your MCU has, "departed."

    You deflect responsibility for failing to note, "VDDC."    Yet - by that "logic" -  do you propose, "PA0, PB0, PC0 etc." be - similarly - renamed?   (their naming is "close" too - is it not?)    Clearly that's a "losing suggestion" - (some) attention to detail IS required!

    Your initial post was very well thought & presented - last one - not so much.    (suspect frustration over-rode your "normal" clear thinking)

    To limit such damage - use of a properly set, "Current Limited" adjustable output, Lab Type Power Supply - is strongly recommended.   Indeed this costs more - yet "savings" will accrue long into the future.     And your MCU, other components, and entire board loss should "escape" such unwanted, premature "departure"...   (and long-standing, MCU naming conventions - this vendor & others - may (properly) persist...)

  • 0 in reply to Amit Ashara
    Prodigy 50 points

    Hi Amit,

    Yes, I plan to replace the parts that were incorrectly powered before continuing testing.  I'm new to TI microcontrollers, so I am not familiar with the fact that VDDC is commonly known to be an LDO output.  On PIC controllers, the LDO capacitor terminal is called VCORE or VCAP.

    Thanks for your help!

  • 0 in reply to mhj555
    TI__Guru**** 244400 points
    Hello mhj555

    All vendors have their own nomenclature, at some places they all agree at other not at all

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Guru 47900 points

    Amit Ashara said:
    All vendors have their own nomenclature, at some places they all agree at other not at all   

    And - as previously stated - to succeed w/multiple vendors - "Attention to Detail" proves best & safest.  

    Current limited supply saves many boards/projects...