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Replacing the TM4C129XNCZAD on TM$X129X-DK

Hey Guys, 

So, I was working on a custom USB-HOST project, in which I communicate and provide power to my Android phone. Unfortunately, out of the blue, my blue led started to stay on. I tried loading various non-USB projects and couldnt control the blue LED  (PQ4). I then measure the voltage on the pin and observed 2.2v on the pin even when I keep the reset button pressed. So, at this point, I think my microcontroller is damaged and need to replace it. 

So, the first question is I need to find answer on my own is how did it happen! I can only assume that somehow my phone outputted voltage to the board! Though, arent there any safety measures implemented on the board? My only external connection to the board was just the USB cable!

Next and the most important question is how do I go about changing the microcontroller on the board (unfortunately its the BGA packaging and need to be done by professionals)? is it doable or worth trying? or Does TI offer any services like that? 

  • mil meh said:
    I communicate and provide power to my Android phone.

    How do you, "provide that power" and how much power does your Android phone require?

    Have you checked and confirmed that your Eval board is capable of powering your Android phone?   Most Eval boards have limited, "external device" powering capabilities.   (as that would raise their size/cost)

    Why is the loss of that one GPIO so critical?  Cannot you cut that trace - and light your blue Led (if that's important) via another GPIO?

    My small tech firm has a full SMT "Pick/Place and 20' long Reflow oven" yet NO (0) BGA capability.   Within the past year we had to swap a BGA device (just one) and the best price we could find was 100 (USD) and that - only after - we begged/pleaded...

    If facts are (really/completely) as you report - I'd bet that ESD visited your MCU board. 

    We do note that "death to the GPIO" powering that blue LED seems (somewhat) common - with absence of more facts - hard to tell if that's cause or effect...

  • Well, I worked with it for the past two months and everything was going smoothly. I use the Tiva in USB host mode and my phone, which supports OTG in slave mode. The phone draws 500 mA at max if I remember correctly and upon connection to the board it showed that the phone was being charged. However, It was never charging the phone as I had my screen on all the time and working on the APP and therefore, it was consuming more that it was getting from the board. So, it could be that it was trying to get more current from the board that the board could handle or ESD. Though, as i said earlier it was working just fine for the past two months. 

    The blue LED is not an issue, the main problem is that the USB port is also not working so I can only imagine that whatever happened (most probably ESD), it damaged some peripherals and changing the uC is the only solution.

  • mil meh said:
    ...The phone draws 500 mA at max... the main problem is that the USB port is also not working

    That "USB port not working" is new data - is it not?   (did not note such - your opening post)

    500 mA - additional current draw - seems beyond the designer's intent for your MCU board!   In fact - is not 500 mA the upper limit for (most all) USB connected devices?   Thus - if a PC's USB Port is your power source - it's 500mA max. output must power (both) your Eval Board & the 500mA (power-hungry) phone.   That's far too much - don't you (now) agree?

    The reported, "Everything going smoothly" - minus the measure of heat & stress upon your MCU board's power-regulating components - may not have been the most factual description.   Such overloads may (sometimes) be tolerated for some time-frame - and then suffer catastrophic failure!   The fact that you could not (easily) sense the over-load does not mean that it wasn't there - and building into a destructive force.

    Had you tried to connect your MCU board to another USB accessory?   Or does that MCU have a 2nd USB Port which you may substitute?

    I noted the difficulty our firm had in "swapping" just one BGA MCU - and the high price.   And - unless the firm is skilled & properly equipped - the replacement may fail.

    One last critical point remains - unless you perform a full/proper "Post Mortem" upon your MCU board - you may "kill" the (expensively) replaced MCU, too!   That would be most unfortunate.   You may avoid that, "worst of all fates" by carefully measuring all voltages upon your board - paying special attention to any/all voltage regulators and other components w/in the power-distribution path.   (Those are the ones most likely to have suffered damage similar to your MCU.)

    As you (now) restate the sequence of events - I've some doubt that the MCU is damaged.   Is it not possible that even "one" of the USB path components has failed - and not the MCU?  

    My sense is that powering of your phone from an Eval board caused over-stress upon your Eval board and possibly even upon the source of power to the Eval board.   (one assumes that's a PC's USB Port)

    I would not be so quick to pronounce your MCU "dead."   If I'm right - you've saved an expensive repair job - and the likely (quick) death of the newly installed replacement MCU....   Your first job now should be a full & proper examination of your Eval board - probing/inspecting every power point - confirming that all voltages are correct and perhaps checking for over-heated components.   If you're fortunate - you may discover a failure along the MCU - USB connector path - which may save you the time, cost, & effort of a major BGA replacement...

  • Hello Mil Meh

    TI does not offer any such services and you would have to handover the board and fresh device to an external PCB vendor.

    Regards
    Amit