ADSP-SC589 EZ-Board® Evaluation System Manual
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The circuit below 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.
The image below shows the equivalent circuit as above but utilizes mechanical 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.
