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Processor extremely hot on EK-TM4C1294XL

Chris McErlean
Prodigy 30 points
Other Parts Discussed in Thread: EK-TM4C1294XL

I have just begun to evaluate the TM4C1294 processor on the EK-TM4C1294XL board.  I am using the IAR IDE EWARM version 7.50.2 and TivaWare version 2.1.2.111.

The board is connected to my PC via U22 - the micro USB debug connector.  This powers the board, connects the debugger to EWARM and appears as a virtual com port for console messages to and from the TM4C1294.  A USB memory is connected to U2 - the target USB connector on the TM4C1294 (via an adapter).

I'm running the "usb_host_msc" project.  This allows the board to detect attachment and disconnection of a USB memory stick and for directory and file browsing.

Generally, the hardware and software works as expected.  However, on two occasions the processor failed to detect the memory stick and became extremely hot - as I found when I burnt my finger on it!  I removed the power immediately and allowed the chip to cool down.  Following this, the system recovered.

It seems that the processor enters some kind of latch-up state.  Note that no other power source is attached to the board.

It is possible the the fault is induced following hitting a breakpoint in EWARM.  However, I have no real evidence for this and I am reluctant to deliberately try to reproduce the fault as I don't know how much more of this ill treatment the processor can withstand.

Any thoughts?

Kind regards,

Chris McErlean

  • 0
    TI__Guru**** 244400 points
    Hello Chris,

    You have run into GPIO#09 Errata. There is no RC filter as listed in the WA on the EK-TM4C1294XL (unlike the DK-TM4C129X). One solution would be not to perform hot plug of the USB Memory Stick.

    Too many heat cycles or prolonged excessive heat due to over current draw may damage the device.

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Prodigy 30 points
    Hello Amit,

    Thank you for your very quick reply! It’s good to know that this is a recognised fault rather than some strange problem with my application. I have read the errata description and may attempt the suggested workaround for the PB0 and PB1 pins.

    Kind regards,
    Chris
  • 0 in reply to Chris McErlean
    TI__Guru**** 244400 points
    Hello Chris,

    The WA on the LaunchPad may be a little tough as the device pins are close without much space to add the RC.

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Prodigy 30 points
    Hello Amit,

    Yes - I'm starting to realise that. I had a good look at the board with a magnifying glass and suspect that my eyesight is not up to the task!

    As I need only the USB embedded host mode (and not the ID pin), I may be able to remove R18 and connect the pad to ground. Alternatively, grounding TP7 may just about do (although it is on the wrong side of R18). Adding a capacitor from TP4 to ground (TP14) may also help. I know that these are quite some distance from the processor pins so may not be effective, but they may be better than nothing.

    Kind regards,
    Chris
  • 0 in reply to Amit Ashara
    Guru 47900 points

    Hi Amit,

    Poster Chris here produced a nicely detailed, thoughtful writing. And yet he encountered a (potentially) serious & destructive issue.

    While such was "covered" w/in MCU errata - how well "promoted" was this errata? Especially as this issue (now) is well known - and as you warn - has the potential to prove destructive.

    Should not a "more effective" warning be employed?

    Poster Chris appears, "on top of his game" - and if he was (inadequately) alerted - might that suggest many others will "fall victim" and that a "superior, more noticeable warning" should be employed?

    Pardon - but crue/I note a, "Bright, Red, Focus Zone" - atop this page - which "promotes" the (always vital) "Blogs, Groups, Videos."   Yet there is, "No Room" for proper: "Tech Warnings, Tech Documents, App Notes, White Papers et. al."   (makes perfect sense - but NOT here - and NOW!)

  • 0 in reply to cb1
    TI__Guru**** 244400 points
    Hello cb1

    I agree, adequate "Red Banner" warning must be provided. Changing the format request has been pushed to the forum web team, and we are working towards a solution that can be more forum centric than a common look and feel...

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

    That would be most wonderful - poster Chris (really) makes the case for "improved alerting AND guiding" client users to greatest success & comfort w/your many diverse products.

    Surely a "common look & feel" has merit - but simply "adding" (or better replacing, "Blogs, Groups, Videos") with pertinent MCU Tech Data Areas - would prove far superior. Having terrific Tech data - yet obscuring it - seems (somehow) NOT best/brightest...