Date: Fri, 25 Nov 2016 10:41:09 -0800 From: Hal Murray <hmurray@megapathdsl.net> To: Ian Lepore <ian@freebsd.org> Cc: freebsd-arm@freebsd.org, hmurray@megapathdsl.net Subject: Re: Can't get 11.0-RELEASE to boot on Banana PI M3 Message-ID: <20161125184109.46C71406061@ip-64-139-1-69.sjc.megapath.net> In-Reply-To: Message from Ian Lepore <ian@freebsd.org> of "Fri, 25 Nov 2016 10:46:26 MST." <1480095986.1889.76.camel@freebsd.org>
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ian@freebsd.org said: > And why exactly is two sources of +5v a problem (not that I said I was doing > that, but I have at times done that, and it works just fine)? That connects 2 regulated power supplies together. They are unlikely to be trying to regulate to the exact same voltage. If the connection is solid, one power supply would probably turn off and let the other do all the work. If the connection is crappy (long thin wires), then they will share the load with the size of each share depending on the voltage from that supply and the resistance of the wires/connectors between the supply and the load. Things get interesting if you turn one supply off. The other supply will try to power everything on that side. That may look like a short circuit. USB sources are supposed to handle short circuits but I wouldn't be surprised if low cost gear got hot or let the smoke out. Power flowing the wrong way isn't something designers think of when they are trying to save pennies. -- These are my opinions. I hate spam.
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