Did you look at the schematic? Those pins have pullup resistors on them. Gerald
On Wed, Jun 10, 2015 at 6:01 PM, <[email protected]> wrote: > I have been trying to use the different GPIO-Pins reserved for eMMC and > tried to use them as GPIO input Pins. Specifically I have been trying to > enable P8_20(Pin 63) as input Pin. My current problem is that even with no > input connection this pin is constantly high and after connecting it to a > circuit with a test LED, the LED started to glow. > > I have been following these two tutorials in order to enable the > conflicting PINS: > > - https://github.com/modmaker/BeBoPr/wiki/BeBoPr-goes-Black > - http://blog.machinekit.io/2013/06/black-is-white-is-grey.html > > > Specifically my steps were the following; > > - Create a bootable SD-card with the latest offical linux > image(3.8.13-bone70) > - Enable the eMMC hardware reset pin while logged onto the Beaglebone > eMMC using the mmc-utils-program,from git clone > https://kernel.googlesource.com/pub/scm/linux/kernel/git/cjb/mmc-utils. > I chose /dev/mmcblk0 as device for the command, not sure if that was the > right one > - Disabled the boot on the beaglebone with the command " > > sudo dd if=/dev/zero of=/dev/mmcblk1 bs=1024 count=1024", executed while > logged in on the Beaglebone > > - Disabled the eMMC and HDMI cape through the command in the uEntv.txt > on the SD-card (found the uEntv.txt file in /boot, uboot is an empty folder > on the SD-card) > - Added "mmc dev 1\n mmc rstn 1\n gpio set 52" to the beginning of the > uEntv.txt file(\n just inserted here to save space the uEntv.txt file has > newlines instead) > - Wrote a Device Tree overlay file that sets the status of Pin 63(33in > pins file) to 37 (from the original 32) > - Loaded my Device Tree Overlay into the Slots file in capemngr > - Echoed 63 to the export file in gpios > > After all these steps the Pin is still displaying a high value without any > kind of circuitry attached. > > The Beaglebone is booting correctly from SD and the Slots file shows that > the eMMC cape has been disabled. The Pins file displays 37 as value for Pin > 33. The exported direction is set to input. I have executed reboots between > most of the above mentioned steps. I have also decompiled the > am335x-boneblack.dtb file and ensured that the status of mmc2 is set to > disabled. > > I am unfortunatly a Computer Scientist with limited background on > electronics, so I am unsure if I have to connect something to the > Beaglebone or if I have to set anymore values. > > I also can not use different Pins as I am working with a Cape that > requires this Pin and some additional ones as input Pins. > > Any feedback or tipps are appreciated. > > Best regards > Sebastian > > -- > 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. > -- Gerald [email protected] http://beagleboard.org/ -- 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.
