Thank you for your reply and explanation.
On Tue, May 12, 2015 at 11:11 PM, Harvey White <[email protected]> wrote: > On Tue, 12 May 2015 21:34:51 -0500, you wrote: > > >I trust that I might save the time of others who want to connect UART4 to > >the Pi-2 UART: It is required to connect the ground of both boards. > > Generally, two electronic systems talking to each other over wires > (not fiber optics, and not ethernet, which uses isolation techniques) > will need a common ground. > > This is especially true of either parallel port driven projects, or > serial (I2C, SPI, CAN, RS-232, to name a few styles). > > MIDI uses isolation techniques. > > Just as when you measure a voltage, you need to measure with reference > to something (typically a ground point), the other circuits that > respond to that voltage need the same (and common) reference point. > This is true unless there have been fairly special techniques used to > bypass that need. > > Remembering this can save you lots of difficulty, however, when in > doubt about connections, ask. > > Harvey > > > > > >-- > > > >Bill Barnett > > -- > 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]. > For more options, visit https://groups.google.com/d/optout. > -- Bill Barnett -- 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]. For more options, visit https://groups.google.com/d/optout.
