On Wednesday, April 6, 2016 at 5:23:55 PM UTC-5, Injun Ear wrote: > > On the BeagleBone Black GPIOs, what is the difference between output > pull-up, output pull-down, and output no pull? > > > In other MCUs I have worked with, pull-up and pull-down are only applied > to inputs. But I have found nothing to specifically say that is the case > with the Beaglebone, and some of the references “seem” to indicate that > outputs can be configured as pull-up and pull-down. > > > If the BBB outputs can be configured for pull-up, pull-down and no pull > then when configured for output pull-up, does that mean that when the port > is enabled (turned on) it will source approximately 3v at up to 4 mA? If > so, then when the port is off, is it in an indeterminate state and need to > be pulled down externally? > > > Or, does it mean that the default setting for the port is pulled high with > minimal current available and that when the port is enabled it will go low > and sink around 4-6 mA? > > > Also, what voltage and current should I expect when the output is set to > no pull up or down? > > > Or, are pull-up and pull-down not options in the output configuration? Is > there any place that specifically says so that I missed (or is this one of > those things that one should be smart enough to know already)? > > > Thank you. >
EDIT: Evidently some MCUs automatically disable the pull up/dn resistors in output mode and others do not. Obviously, no pull means both resistors are disabled. It is possible that enabling either of the pull resistors in output mode may cause a no load voltage to go high or low. But it's possible that the current would be very small and easily overridden by the regular output current. This is only a guess. Confirmation or clarification would be sincerely appreciated. -- 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 beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
