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BeagleBone White Power LED blinking

Don Chakkappan
Prodigy 230 points
Other Parts Discussed in Thread: L293D

I am working with BeagleBone white . Recently i have losted my 5 pieces of BeagleBone White  due to some voltage issues. 

Now , the power LED is just blinking when i powered the BBW. Is it completely lost ? Is there any solution or work-around to bring my BBW back....

I really need your support & help. Please

  • 0
    TI__Guru**** 393215 points

    Power LED blinking on the Beaglebone means that the PMIC is cycling, trying to start up. For proper start the PWR_EN signal must come from the processor within 5s. If this does not happen the PMIC power cycles. From what you describe probably you have a processor failure.

  • 0 in reply to Biser Gatchev-XID
    Prodigy 230 points
    Dear Biser Gatchev-XID Sir

    I am very very happy to see your quick answer . So , what can i do next ?

    I am very sad to throw my BBW boards. Could you please suggest me any solution ?
  • 0 in reply to Don Chakkappan
    TI__Guru**** 393215 points

    There is nothing I can do to help over the forum. The boards need to be repaired. I don't know if you can do this by yourself.

  • 0 in reply to Biser Gatchev-XID
    Prodigy 230 points
    One of my friend will repair the Board . As per his suggestion i have ordered TPS65217BRSLR IC from Texas Instruments.

    TPS65217BRSLT is shows as no stock in TI . Replacement of TPS65217BRSLR will solve the issue ?

    Whats the difference between TPS65217BRSLR & TPS65217BRSLT ?
  • 0 in reply to Don Chakkappan
    TI__Guru**** 393215 points

    Don Chakkappan said:
    Whats the difference between TPS65217BRSLR & TPS65217BRSLT ?

    First one is packaged in Rails, second one in Tape. However I'm not sure this will solve your problems. It's more than likely that the processors have failed, seeing that you wrote about "some voltage issues" in your first post above.

  • 0 in reply to Biser Gatchev-XID
    Prodigy 230 points
    Dear Biser

    Is there any option to ensure the issue is with PMIC ? I don't have enough patience to wait upto ordered ICs arrives.

    Could you please provide some guidelines to avoid these kind of power related issues . I am totally a green-horn in embedded/electronics domain .

    Your suggestions and solutions are much helpful to me. Lot of thanks for your help and suport . . .
  • 0 in reply to Don Chakkappan
    TI__Guru**** 393215 points

    The one most important thing to observe is never to connect any cape or other periphery to the Beaglebone while it's powered. Another important thing is that the AM335X I/O pins are not fail-safe. This means that they should never be subjected to voltages that exceed the respective VDDSHVx supplies (3.3V in Beaglebone case). Also if active peripherals are connected you must ensure that the power supplies ramp up together, i.e. you should never connect a powered peripheral to an unpowered Am335X and vice versa.

    As for the PMIC, what you can do is measure the power outputs. They will pulse along with the power LED, but you should be able to see if all voltages are present.

  • 0 in reply to Biser Gatchev-XID
    Prodigy 230 points

    Here i will post schemtic of my system . (I am a fresher to Eagle). Could you please   find the  bad practises i have designed.

    The IC L293D's 5V supply @ VCC2 is taken from SYS_5V of P9 header of BeagleBone. Is it a bad practise ? 

    And  i didn't understand the things you mentioned about PMIC . If the issue is only with PMIC , then what should be the expected behaviour of BB. 

    How can i test it ? . . . 

    How can i check the health of processor ? .

    I am waiting for your great reply dear Biser . . . . . . . 

  • 0 in reply to Don Chakkappan
    TI__Guru**** 393215 points

    The problem is very simple. Your L293D is powered at 5V. AM335X I/O pins in Beaglebone are powered from 3.3V and are NOT 5V tolerant. You must use level shifters when you interface to any voltage different from 3.3V.

    You can safely assume that your processors have failed. There is probably nothing wrong with the PMICs.

  • 0 in reply to Biser Gatchev-XID
    Prodigy 230 points

    I got the references from BeagleBone cookbook chapter4 like , 

    Then what i am missing ?

    And , i can't use the damaged boards any more ?

    And what is the best design to achieve the system i have tried ? . . .

  • 0 in reply to Don Chakkappan
    TI__Guru**** 393215 points

    I don't have this book, but from what I see power for the external board is taken from P9 pins 1 and 3, which are GND and +3.3V.

    As for your boards I cannot help. The processors need to be changed at least.