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[SOLVED] TM4C1294 Connected Launcpad Not powering up

Shubhojyoti Ganguly
Prodigy 90 points


My EK-T4MC1294XL Launchpad was working perfectly yesterday. I made no changes in my setup after that but somehow the launchpad stopped working.

Today, when I connected the Launchpad to the Computer, it was suddenly not powering up and getting heated. My Power selection Jumper was in the correct position (ICDI).

I changed the Power selection jumper to OTG and Booster and tried providing power through them respectively but the Launchpad is still not powering up and getting heated.

The zone that is getting heated is marked in the picture.

  • Initially, I thought the U5 TPS73733 voltage regulator must have got damaged. So, I removed the JP3 jumper to disconnect the regulator and selected the JP1 jumper to take input power from the Booster pack. Then I tried powering the board from a 3.3v output of an Arduino by putting the 3.3v and GND in the booster pack. The board is still not powering up and there is no heating also. The datasheet mentions that powering from 3.3v in this way should work but it doesn't.

This shows, there has been a power short before the voltage regulator.

  • Then while the JP3 jumper was open, I supplied 5v and ground to the booster pack from Arduino and checked the voltage at the JP3 terminals. There was a 3.3v across JP3. But when I put the JP3 jumper back in, the circuit got shorted the Arduino turned off. I immediately removed the jumper to protect my arduino.

This shows, there has been a short after the power regulation. 

As you see, both conclusions are contradictory and this is confusing me in finding out what is the problem. Most likely, I have missed some key piece of information about the schematic.

Please help, the launchpad is an integral part of a motion control system that I am working on.

  • 0
    TI__Guru**** 472411 points
    Hello,
    I will move your post to the Tiva forums, where the experts there can help you best.

    Thanks
    ki
  • 0
    Guru 20670 points
    Can you check if any pins on the components are touching?

    This is not that contradictory.
    Think now.

    The 5V are direct from the USB port. Short = the fail safe on the USB to cut power = arduino off.
    The 3.3V are through a voltage regulator. Like many voltage regulators the arduino uno's one should also have a similar failsafe. If it does consider this - the voltage 3.3V regulator turns off = Arduino still on no? The 5V domain is untouched and no extra power is drained from it since the 3.3V reg turned off.

    Did you check the voltage on the first setup with the 3.3V regulator on the arduino powering the Tiva? I don't even think it has enough power for the TM4C1294 alone (the regulator is only for 50mA) and I am not sure if the debugger (which is another TM4C1294) would also be powered (I have not voltmeter here to check) which would mean even more current needed - just go check the datasheet - at 120Mhz it can drain 100mA or something like that.

    So check for shorts, check the voltage with the 3.3V arduino pins powering it and do come back with the results
  • 0
    TI__Guru**** 244410 points
    Hello Shubhojyoti

    For the first experiment of supplying 3.3V after removing JP1, did the LED come ON? If yes, then what was not coming up, was it the ICDI MCU not showing up on the Windows device manager?

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Prodigy 90 points

    No, the LED did not light up. When I said, the launchpad did not power up, I meant that only. The board is not powering up and the LED is not lit.

    Is there a possibility that the LED is causing the short because the area that is getting heated up also contains the LED.

  • 0 in reply to Luis Afonso
    Prodigy 90 points
    I have no additional components attached to the launchpad or arduino. And the Arduino is working perfectly so there is some internal short within the launchpad itself.

    I checked the voltages and you are correct. The 3.3v regulator from arduino is shutting off and there is no voltage coming on 3.3v pin once I connect it to the launchpad. When I disconnect it, the 3.3 v is back on.

    So, there is some short after the U5 TPS73733 voltage regulator.

    IMPORTANT UPDATE!!
    After finding out, there is a short after the U5 TPS73733 regulator, I connected the JP3 jumper and disconnected the JP2 jumper to stop power in the microcontroller and the Power LED turned ON. In this configuration, the board was powering up from both 5v and 3.3v pins.
    This shows, the short is within the T4MC1294's microcontroller. Most probably, the microcontroller is dead or burnt.

    Is there any way to fix my launchpad or revive the microcontroller?
    Can you tell me what could have possible caused this?
  • 0 in reply to Shubhojyoti Ganguly
    Guru 26105 points

    Hi,

    Here you have the board's user manual, including electrical diagrams: 

  • 0 in reply to Petrei
    Prodigy 90 points

    I already have this document

  • 0
    Guru 117855 points

    Shubhojyoti Ganguly said:
    launchpad is an integral part of a motion control system that I am working on.

    If that motion control system's LPad is important enough to you to warrant, "Urgent" should you not have acquired "spares?"   Such misfortune is not entirely unexpected - especially when power components (normal/customary when "controlling motion") - enter the playing field.

    My small tech firm annually builds ships beyond 10K MCU-based boards annually - our incidence of MCU failure - as you report - is, "in the noise."   And - most always when it does occur - the fault is clearly ours - (almost) never the MCU!

    I suspect that one (or several) of these "user induced" behaviors caused your plight:

    • MCU's power was reversed or otherwise outside of spec
    • MCU's connections to "outside world" enabled a damaging signal level/polarity to arrive
    • ESD - although this is not noted for causing the "totality of failure" you report

    Your report reveals great (unusual) familiarity on/around the power input & distribution channels of your board.   Such (may) suggest that you (earlier) attempted a, "non-standard" means of powering this board - or attempted to (steal/borrow) power from this board for another (board or component).   Any such action - performed incorrectly (even briefly) would explain your present, "dead bug" misfortune.

    While we, "feel your pain" I believe the odds are extremely high that "user error" was the culprit - and your identification and correction may best warrant, "Urgent!"

    Note that ALL poster's believe their need/issue to qualify as, "urgent."   Those (smart enough) to avoid that word (usually) earn far faster (and better) response as they escape the unwanted, "scent of entitlement!"

  • 0 in reply to cb1_mobile
    Prodigy 90 points

    cb1_mobile said:
    should you not have acquired "spares?"

    The T4MC1294XL launchpad was not available more than one at the India distributor of this launchpad. There are no other distributors. However, I have a Arduino mega and will try using it instead of the T4mc1294 until stocks arrive but the mega has far lesser features than the launchpad and porting all the code is time consuming.

    cb1_mobile said:
    MCU's power was reversed or otherwise outside of spec

    As far as I know, if I had made some mistake in connecting the MCU power, the microcontroller would go dead immediately and not start up anymore. But this hasn't happened. As I said the board was working fine the previous night, I packed it up in the ESD-safe bag provided and went to sleep. The next morning I wake up and connect it to find it is dead.

    Moreover, I had never used the 3.3v from the jumper pack to power the launchpad (except after it went dead). I had either used a 5v from a 7805 voltage regulator or the USB Cable with one end connected to the computer. Both these sources passed through the 3.3 voltage regulator before reaching the microcontroller. If I ever made any mistake in reversing the power terminal, the voltage regulator would get damaged leaving the microcontroller unharmed.

    cb1_mobile said:
    • MCU's connections to "outside world" enabled a damaging signal level/polarity to arrive

    I did not use any breadboard or loose wires to connect components to the launchpad. I designed a proper interface using a PCB to connect only this motor driver (https://www.pololu.com/product/708/blog). If I made any mistake in designing the PCB, the system would not have worked properly from the start. Moreover, Pololu motor drivers are very safe to handle and if you look at their datasheet you will find out that there is very less chance of reverse current flowing in.

    This leaves the damage by ESD in which I have nothing to do.

    cb1_mobile said:
    Your report reveals great (unusual) familiarity on/around the power input & distribution channels of your board.

    My familiarity is because I had designed my own microcontroller boards from scratch using ATmega16/32 and some other AVR Microcontrollers. I am not super familiar with the registers in ARM microcontrollers but the power distribution and most other electronics components are similar. Since this was a very vital component, I had not tinkered too much with the launchpad but I read the datasheet in detail and I understood the overall working before ordering it.

    PS: The PWM was probably not working properly before the launchpad went dead altogether. I had already started a thread on it in the Pololu forums as I thought it was a problem with the motor driver. Please have a look at this thread: http://forum.pololu.com/viewtopic.php?f=15&t=10619 . This thread contains pictures, wiring diagram and code of the motion control system also.

    www.pololu.com/.../blog

  • 0 in reply to Shubhojyoti Ganguly
    Guru 117855 points

    Shubhojyoti Ganguly said:
    ... the previous night, I packed it up in the ESD-safe bag provided and went to sleep. The next morning I wake up and connect it to find it is dead.

    Might that (w/in highlight) suspected, "excess handling" be a cause.   Surely cannot help.   When my firm tests/verifies - we (avoid) any "excess of handling" as this raises the probability of subsequent mis-connection and/or ESD intrusion.

    Shubhojyoti Ganguly said:
    If I made any mistake in designing the PCB, the system would not have worked properly from the start.

    Such thinking is (more) wishful than factual.   Often times we're called to visit clients w/similar claims - what (appears) to "work" may in reality be, "Not fully proper" & may "let in" damaging transients - which in time - wreak their harm!

    Shubhojyoti Ganguly said:
    xyz motor drivers are very safe to handle

    I know of (few) motor drivers - which while in prototype connection & operation - and software development - are "very safe" to handle!

    I would wager (very) large sum that a proper, "post mortem" of your MCU will reveal, "User caused!"   Rather than defend (existing) practices - it may prove more productive to further review these, "usual suspect/causes."

    You should note that vendor reps here are (most always) unable to, "Offer a free replacement" for your (claimed) defective LPad...

    MCU deaths - as you describe - are rarely, "suicidal!"  (i.e. MCU's "self-inflicted/directed" action)

  • 0 in reply to cb1_mobile
    Prodigy 90 points
    I am not denying the fact that it might be my fault that the microcontroller is dead but I am interested in understanding what could have caused this. Otherwise, I will buy a replacement and continue any malpractice unknowingly and damage the new microcontroller once again like before.

    To prevent this, I am interested in doing the "post-mortem" of my launchpad to know what cause this. If you know how to do this, please do tell me.

    Also, you seem to be very experienced in this, please do tell some safe motor controllers which I can use in the future. I need to control the pololu 50:1 200 rpm motors (Look at the thread I gave link to in the previous reply ) and also get feedback from a 64 CPR encoder to run a PID loop. Please suggest the best hardware that might help me do this. Previously, I was using the VNH2SP30 to drive the motors and the launchpad was being used to read the encoders and run the PID loop.
  • 0 in reply to Shubhojyoti Ganguly
    Guru 117855 points
    Such "post mortem" is performed by the vendor - and (usually) as a courtesy to firms purchasing in (some) quantity. Having a good relationship w/vendor's local Sales Staff - vastly aids this accommodation. (such seems "outside" your case)

    DigiKey stocks this board - I don't know about shipping charges to India - but to Taiwan, Japan - seems, "Not so bad."

    Firm/I believe that the best way to "achieve" a "safe" connection to motor controller - is to "NOT trust" the motor controller! Do all in your power to prevent damaging transients, improper current flows, and external, powered connections from "landing" upon your "UNPowered" MCU.

    Pardon but may I "pass" on recommending & advising in the (further) detail you seek? Others call too - although none have expressed, "Urgent" - and it is those to which I first focus & respond... Bon chance, mon ami...