REF: BBONEBLK_SRM
BeagleBone Black System
Reference Manual
Rev A5.2
Page 93 of 108
other functions found on those pins. You will need to override the resistor values in order
to change the settings. The DC pull-up requirement should be based on the AM335x Vih
min voltage of 2 volts and AM335x maximum input leakage current of 18uA. Also take
into account any other current leakage paths on these signals which could be caused by
your specific cape design.
The DC pull-down requirement should be based on the AM335x Vil max voltage of 0.8
volts and AM335x maximum input leakage current of 18uA plus any other current
leakage paths on these signals.
8.4
Expansion Connectors
A combination of male and female headers is used for access to the expansion headers on
the main board. There are three possible mounting configurations for the expansion
headers:
Single-no board stacking but can be used on the top of the stack.
Stacking-up to four boards can be stacked on top of each other.
Stacking with signal stealing-up to three boards can be stacked on top of each
other, but certain boards will not pass on the signals they are using to prevent
signal loading or use by other cards in the stack.
The following sections describe how the connectors are to be implemented and used for
each of the different configurations.
8.4.1
Non-Stacking Headers-Single Cape
For non-stacking capes single configurations or where the cape can be the last board on
the stack, the two 46 pin expansion headers use the same connectors.
Figure 57
is a
picture of the connector. These are dual row 23 position 2.54mm x 2.54mm connectors.
Figure 57.
Single Expansion Connector
The connector is typically mounted on the bottom side of the board as shown in
Figure
58
. These are very common connectors and should be easily located. You can also use
two single row 23 pin headers for each of the dual row headers.
