What I would do is some minor surgery on the PocketBeagle, disconnecting the +5V lead coming in the microUSB connector. The easiest way to do this would be to remove FB1 (ferrite bead in series with USB +5). Easy with "hot tweezers", or a pair of small soldering irons. To restore the Pocketbeagle to factory configuration, solder FB1 back in.
Short P1-Pin-1 and P1-Pin-7 together, and power the Beagle from whatever you are going to power it with at +5V. No issues with instability. Now you can plug in USB for programming and anything else you want/need to do, at any time. It just won't take power through the USB cable any more. --- Graham == On Sat, Aug 10, 2019 at 12:18 AM Jim F <[email protected]> wrote: > 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 <[email protected]> wrote: > >> At Fri, 9 Aug 2019 17:01:28 -0400 [email protected] 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 <[email protected]> >> 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 >> > > [email protected] -- Webhosting Services >> > > >> > > >> > > -- >> > > For more options, visit http://beagleboard.org/discuss >> > > --- >> > > You received this message because you are subscribed to the Google >> Groups >> > > "BeagleBoard" group. >> > > To unsubscribe from this group and stop receiving emails from it, >> send an >> > > email to [email protected]. >> > > To view this discussion on the web visit >> > > >> https://groups.google.com/d/msgid/beagleboard/20190809193224.14FD526C0099%40sharky3.deepsoft.com >> > > . >> > > >> > >> >> -- >> Robert Heller -- 978-544-6933 >> Deepwoods Software -- Custom Software Services >> http://www.deepsoft.com/ -- Linux Administration Services >> [email protected] -- Webhosting Services >> >> >> -- >> For more options, visit http://beagleboard.org/discuss >> --- >> You received this message because you are subscribed to the Google Groups >> "BeagleBoard" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/beagleboard/20190810010630.52DDF26C0099%40sharky3.deepsoft.com >> . >> > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to a topic in the > Google Groups "BeagleBoard" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/beagleboard/FwmkeG4itT0/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/beagleboard/CAGS%2B2h97hjeZJJtZ7wFkfBATEs9QvN4ewR_uL23zjW9SpHhx6w%40mail.gmail.com > <https://groups.google.com/d/msgid/beagleboard/CAGS%2B2h97hjeZJJtZ7wFkfBATEs9QvN4ewR_uL23zjW9SpHhx6w%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. 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