Thanks for the info Serge! I did some more tests, and it looks like applying the DTO will set some parameters of the pin, but not others. You always need to manually set the state using the files in order to get a guaranteed state. For example, let's say that I set a pin to be an Input w/ a pullup using the DTO. The actual pin may still be set to an output. But if I manually set the pin as an input using "direction" file, then the input pin will read high due to the pullup set in the DTO. Similarly... if a pin is set w/ a pulldown in the DTO, then the actual pin will read low only when you switch it to an input using the "direction" file.
It seems strange that a pin set as an input in the DTO could be set as an output using the files(and vice versa), but I guess that's just how it works. Need to be very careful to avoid inconsistent pin states. On Saturday, June 21, 2014 9:14:41 PM UTC-7, serge...@gmail.com wrote: > > > > Hi Michael > > > When I do 'cat value' in the gpio48 directory, I get 1. I should get a > 0 since the pulldown is enabled. > >> To my experience the 'cat value' not always reflects actual level on the > wire. > and > > Should modifications in the DTO reflect in the file interfaces and on > the physical pin itself, > DTO modifications not always change the pinmux settings or pin state. (For > example uEnv.txt settings might override them) > > I concluded useless to study roots of every case, as well as got tired > from checking pinmux settings and wire levels every time I connect new > device to the system, and wrote small linux utility showing the punmux > settings, GPIO configurations, and wire levels(if GPIO receiver enabled). > Maybe it will be helpful in your case, to understand what is where: > www.academ.org/~sv/epc/pinmux.pdf > > Serge > > > > -- 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.
