Analog Devices EZ-KIT Lite ADSP-BF707, Системное руководство

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ADSP-BF707 EZ-KIT Lite Evaluation System Manual 2-5
ADSP-BF707 EZ-KIT Lite Hardware Reference
Figure 2-3 shows the equivalent circuit to Figure 2-2 but utilizes mechan-
ical switches that are in the same package. Notice the default is shown by
black boxes located closer to the
ON
label of the switches. In order to dis-
connect these switches, physically move the switch to the
OFF
position.
Figure 2-4 shows a bus switch example, reference designator UC (Pericom
PI3LVD512ZHE), selecting between lettered functionality and numbered
functionality. The signals on the left side are multiplexed signals with
naming convention
letter_number
. The right side of the circuit shows the
signals separated into letter and number, with the number on the lower
group (eg.
0B1
) and the letter on the upper group (eg.
0B2
). The default
setting is controlled by the signal
CONTROL_LETTER_NUMBER
which is pulled
low. This selects the number signals on the right to be connected to the
multiplexed signals on the left by default. In this example, the Microchip
IO expander is not shown but controls the signal
CONTROL_LETTER_NUMBER
and allows the user to change the selection through software.
Figure 2-5 shows the equivalent circuit to Figure 2-4 but utilizes mechan-
ical switches. Notice the default for reference designators
SWC
and
SWD
is
illustrated by black boxes located closer to the
ON
label of the switches to
enable the number signals by default. Also notice the default setting for
reference designators
SWE
and
SWF
is
OFF
. In order to connect the letters
instead of the numbers, the user physically changes all switches on
SWC
and
SWD
to the
OFF
position and all switches on
SWE
and
SEF
to the
ON
position.
Figure 2-3. Example of Mechanical Switch Equivalent to Figure 2-2