Robert:

It has been a while, almost a year since I did any testing with the 
PocketBeagle.
But I don't think anything has changed relative to my comments below.
Maybe someone can correct me if I am wrong, and some things have been fixed.

P1-Pin-1 is Vin, and is equivalent to the Barrel Jack input on the 
Beaglebone Black, it
is a separate power supply input, and is isolated from the microUSB 
connector power.

P1-Pin-7 is hardwired to the +5 pin on the microUSB connector, USB Port 0.
It is not clear from the schematic, but is visible if you view the PCB 
board plots.
Or check it with an Ohmmeter.

I found that the PocketBeagle, when powered exclusively by P1-Pin-1 would 
randomly
crash about once every 24 hours of operation, without any apparent reason, 
or
any clue in the logs. I hope that this has been fixed, but I have seen 
other reports
since I initially reported it, and nothing since that reported a fix.

The only workaround I found was to power P1-Pin-1 and P1-Pin-7 in parallel, 
in which case
it does not crash, but now there is no isolation between USB +5V and your 
independent
PB power supply, and, as you are concerned about, all kinds of cross-feed 
and back
powering can occur.

I suggest you read the email thread "PocketBeagles are Unstable" started 
11/24/2017

--- Graham

==


On Friday, August 9, 2019 at 2:33:15 PM UTC-5, Robert Heller wrote:
>
> If I am applying a 5V power supply to the Vin pin (P1-1) of a Pocket 
> Beagle 
> (say from an expansion board that includes a power supply), is it safe to 
> also 
> plug in a [powered] micro-USB cable? That is, does the Pocket Beagle have 
> a 
> power protection / isolation circuit? 
>
>
>

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