The HDMI port on the BeagleBone Black is implemented as a virtual cape. This virtual cape uses pins on the expansion headers, limiting the available pins. If you don’t need HDMI you gain 20 more GPIO pins by disabling the HDMI cape. Other reasons for disabling HDMI are to make UART 5 and the flow control for UART 3 and 4 available or to get more PWM pins. Follow the instructions below to disable the HDMI cape and make pins 27 to 46 on header P8 available.
Before you start, it’s always a good idea to update your BeagleBone Black with the latest Angstrom image.
user name: root
Mount the FAT partition:
mount /dev/mmcblk0p1 /mnt/card
Edit the uEnv.txt on the mounted partition:
To disable the HDMI Cape, change the contents of uEnv.txt to:
Save the file:
Unmount the partition:
Reboot the board:
shutdown -r now
Wait about 10 seconds and reconnect to the BeagleBone Black through SSH. To see what capes are enabled:
Every line shows something like “P-O-L” or “P-O–“. The letter “L” means the Cape is enabled; no letter “L” means that it is disabled. You can see here that the HDMI Cape has been disabled, so pin 27 to 46 on header P8 are now available to use.
Credits: based on Beagleboard.org forum posts by Günter Pütz and others.