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 or 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)?