The only way you're going to solve this most likely is by debugging via
JTAG.

On Sat, May 14, 2016 at 8:21 PM, Wally Bkg <[email protected]> wrote:

>
> Other than the GPIO interface pins on the P8 connector (something like 34
> inputs and 4 outputs) the only other connections are the 5V power supply
> "barrel connector" and the Ethernet cable.  It wasn't just a communication
> failure, all the on board LEDs were out, which is why I'd thought the 5V
> power supply had failed initially.   After the power supply was measured to
> be putting out 5V I expected it to boot when plugged in again, but it
> didn't, although some of the LEDs did lite up.  Although later it booted
> normally after sitting unplugged for 15-20 minutes.
>
> I might think some kind of thermal cutout happened and needed time to cool
> down and "reset", but very early on in the development I determined that
> nothing on the board heads up significantly in long term operation.
>
>
> On Saturday, May 14, 2016 at 9:32:47 PM UTC-5, William Hermans wrote:
>>
>> This happens to a RevC BBB we have here when a serial debug cable is
>> attached, and using cat /dev/ttyUSB0 on the remote end. This does not seem
>> to happen when using screen, or minicom. But the reason why cat was used
>> was the output from screen, or minicom became garbled over time.
>>
>> However, unplugging the serial debug cable ( PL2303hx ) on the USB sides
>> cures the glitch.
>>
>> On Sat, May 14, 2016 at 3:53 PM, Wally Bkg <[email protected]> wrote:
>>
>>> I've a BBW (Rev A6) that has been running an IOT application 24/7 for 5
>>> or 6 months now.  Its worked great, until now.
>>>
>>> I had a weird hard lockup where it stopped with all the LEDs off and
>>> didn't respond to the reset button.  I immediately suspected failure of the
>>> 5V supply as the 12V parts of the system were still alive
>>>
>>> I unplugged the power supply and it wasn't dead.  When I plugged it back
>>> in after a quick test of the power supply, one green LED and both Ethernet
>>> LEDs lit but it still didn't boot or respond to the reset button (which I
>>> left accessible via a pencil point on purpose).  I unplugged the power
>>> supply again and left it unplugged while I checked a few other things.
>>> About 15 minutes later, still scratching my head and fretting about the
>>> hassle of swapping in my BBG I have on hand as a spare,  I plugged the
>>> power supply back in to make a few more measurements (access to the board
>>> is difficult, but key interface circuit points are probe-able)  and the
>>> thing booted right up and is working nominally again.
>>>
>>> Any ideas what could have caused this need for a long interval without
>>> power before it would boot?
>>>
>>> One of the other devices in the IOT system sent me a "no hearbeat" Email
>>> message about it, as designed, but since a simple power cycle didn't
>>> initially cure it, this could be a real problem eventually, (I haven't
>>> yet implemented the planned power cycling hardware).  Needing a 15-20
>>> minute power down to reset could be hard to deal with
>>>
>>> The BBW is on a UPS, same one as the router which never glitched,  so
>>> its hard to see it as a AC power issue, although a thunderstorm is moving
>>> through the area (small one by our standards and I never noticed the lights
>>> dim or flciker).  Also the Raspberry Pi2 which sent the "no hearbeat"
>>> message never glitched, despite not being on a UPS.
>>>
>>> I'm mystified by this "long time constant" for the power cycling to have
>>> any effect.  Nothing  on the BBW gets other than barely delectably warm to
>>> a finger touch.
>>>
>>> Any ideas?
>>>
>>> --
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>>
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