How to access GPIO_38, GPIO_39 and so on as digital input pins

[Sujit Singh]

I want to access GPIO_38, GPIO_39, GPIO_34, GPIO_35 in order to use it as digital input pins but as they are not normal GPIO pins, how do I use them as digital input or output pins. 

[Mark A. Yoder]

Sujit:

  By default those pins are used by the eMMC (on board flash).  If you are running from an SD card you can turn off the eMMC and use those pins.  Just edit /boot/uEnv.txt and find the line:

##BeagleBone Black: eMMC disabled:

#dtb=am335x-boneblack-hdmi-overlay.dtb

and uncomment the dtb line and reboot.  You should then have access to those GPIO pins.

--Mark

[Sujit Singh]

Thanks Sir, Do you have any idea about the same in an android OS, as I am unable to locate /boot/uEnv.txt from my android sd card os.

[Mark A. Yoder]

Sorry, I don't know how to do that under Android.  I think /boot/uEnv.txt is unique to the Beagle.

--Mark