Ahhh. I've had some of this pain. I did actually raise xmodem from the
dead, but had enough problems that I just got a secondary USB port working
and put a wifi dingle on it. Anyway what you want to do, sounds like it
will work.
On Fri, Aug 9, 2019, 9:07 PM Robert Heller <hel...@deepsoft.com> wrote:
> At Fri, 9 Aug 2019 17:01:28 -0400 beagleboard@googlegroups.com wrote:
>
> >
> >
> > Robert,
> >
> > If you have a look at the Pocketbeagle schematic, you can see what
> happens
> > with the USB connector, which comes in on page 2. Power on that pin goes
> to
> > VIN.USB, which goes straight to (page 3) the Octavo OSD3358 VIN_USB pins.
> >
> > You can look at the Octavo datasheet [1] - it's for the OSD335x_SM - they
> > tell you almost nothing. The only partly useful thing they tell you is
> "The
> > OSD335x-SM may be powered by any combination of the following input power
> > supplies. Please refer to the TPS65217C datasheet for details." The
> > smartest thing to do would be to map the pins to the chips they are
> > connected to using Octavo's tool [2] and the TI datasheets. I'm certain
> > there's no isolation, but there is a switch to enable one or the other
> > inputs (perhaps you had a looser definition of isolation in mind). Figure
> > 11 on page 27 of the TPS65217C datasheet [3] should show you what that
> > looks like. These are configured by the PPATH register in [3], which I am
> > not precisely certain how it is configured in the first place, but you
> > should be able to modify it on I2C0 (I think).
> >
> > All that said, it looks to me like it's fine to do. But I feel like I've
> > done this and had some weird results, I just can't remember exactly what
> > they were. I think the results included unplanned reverse power flow (USB
> > charging other things connected to the same VIN power supply), the device
> > not shutting down exactly as I expected, and similar behavior. I don't
> > think we smoked anything, though, so there's that. Worth looking through
> > that data sheet a little to make sure you're happy first.
>
> OK. The reason I want to know is that I have an expansion board that
> supplies
> power (and does other things). It does have a serial console header, so I
> can
> connect a TTL serial<=> USB cable for debugging, but unless I really want
> to
> raise XModem (from the dead?) there isn't any way to do something like
> download a fresh executable program ("cross" built on a RPi). I just
> wondered
> if it is "safest" to just unplug the Pocket Beagle from the expansion
> board
> and tether it to my laptop and use the Tcp/Ip over USB to do the "large"
> transfers of things like exe files, etc. This is what I have been doing
> and
> was wondering if I really have to do it that way or if I can plug in the
> USB
> while the Pocket Beagle is still being powered by the expansion board.
>
> >
> > I would be quite interested to know precisely where PPATH is configured,
> > beyond its default settings. It may be in the uboot source which is not
> [I
> > think] in the BB distributions. That stuff isn't bad to look at, and I
> was
> > going to, but for the life of me I can't remember where I built that and
> I
> > can't find it right now. Robert also has a few scripts in
> /opt/scripts/boot
> > which configure a LOT of things, I've only scratched the surface trying
> to
> > understand them.
> >
> > [0] -
> >
> https://github.com/beagleboard/pocketbeagle/blob/master/PocketBeagle_sch.pdf
> > [1] - https://octavosystems.com/docs/osd335x-sm-datasheet/
> > [2] -
> https://octavosystems.com/app_notes/osd335x-family-pin-assignments/
> > (search for VIN_USB)
> > [3] - http://www.ti.com/lit/ds/symlink/tps65217.pdf
> >
> > Hope that helps. I have nothing to do with the pocket beagle but I did
> spin
> > a couple boards based on it and the octavo RED board.
> >
> > Best,
> >
> > Jim
> >
> > On Fri, Aug 9, 2019 at 3:33 PM Robert Heller <hel...@deepsoft.com>
> 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?
> > >
> > > --
> > > Robert Heller -- 978-544-6933
> > > Deepwoods Software -- Custom Software Services
> > > http://www.deepsoft.com/ -- Linux Administration Services
> > > hel...@deepsoft.com -- Webhosting Services
> > >
> > >
> > > --
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> > > .
> > >
> >
>
> --
> Robert Heller -- 978-544-6933
> Deepwoods Software -- Custom Software Services
> http://www.deepsoft.com/ -- Linux Administration Services
> hel...@deepsoft.com -- Webhosting Services
>
>
> --
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