At Fri, 9 Aug 2019 17:01:28 -0400
beagl...@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
download a fresh executable program ("cross" built on a RPi). I just wondered
transfers of things like exe files, etc. This is what I have been doing and