beaglebone-black - Flipbook - Page 82
Chapter 8
Cape Board Support
The BeagleBone Black has the ability to accept up to four expansion boards or capes that can be stacked onto
the expansion headers. The word cape comes from the shape of the board as it is 昀椀tted around the Ethernet
connector on the main board. This notch acts as a key to ensure proper orientation of the cape.
This section describes the rules for creating capes to ensure proper operation with the BeagleBone Black and
proper interoperability with other capes that are intended to coexist with each other. Co-existence is not a
requirement and is in itself, something that is impossible to control or administer. But, people will be able to
create capes that operate with other capes that are already available based on public information as it pertains
to what pins and features each cape uses. This information will be able to be read from the EEPROM on each
cape.
This section is intended as a guideline for those wanting to create their own capes. Its intent is not to put limits
on the creation of capes and what they can do, but to set a few basic rules that will allow the SW to administer
their operation with the BeagleBone Black. For this reason there is a lot of 昀氀exibility in the speci昀椀cation that we
hope most people will 昀椀nd liberating and in the spirit of Open Source Hardware. I am sure there are others that
would like to see tighter control, more details, more rules and much more order to the way capes are handled.
Over time, this speci昀椀cation will change and be updated, so please refer to the latest version of this manual
prior to designing your own capes to get the latest information.
DO NOT APPLY VOLTAGE TO ANY I/O PIN WHEN
POWER IS NOT SUPPLIED TO THE BOARD. IT WILL DAMAGE THE PROCESSOR AND VOID THE WARRANTY.
NO PINS ARE TO BE DRIVEN UNTIL AFTER THE SYS_RESET LINE GOES HIGH.
8.1 BeagleBone Black Cape Compatibility
The main expansion headers are the same between the BeagleBone and BeagleBone Black. While the pins are
the same, some of these pins are now used on the BeagleBone Black. The following sections discuss these
pins.
The Power Expansion header was removed from the BeagleBone Black and is not available.
PAY VERY CLOSE ATTENTION TO THIS SECTION AND READ CAREFULLY!!
8.1.1 LCD Pins
The LCD pins are used on the BeagleBone Black to drive the HDMI framer. These signals are listed in Table 15
below.
77
