ADSP-BF527 EZ-KIT Lite Evaluation System Manual
1-17
Using ADSP-BF527 EZ-KIT Lite
Rotary Encoder Interface
The ADSP-BF527 processor has a built-in, up-down counter with support
for a rotary encoder. The three-wire rotary encoder interface connects to
the rotary switch (
SW3
) and expansion interface connector. The rotary
encoder can be turned clockwise for the up function, counter clockwise
for the down function, or can be used as a push button for clearing the
counter.
The rotary switch is a two-bit quadrature (Gray code) counter with
detent, meaning that both the down signal (
CDG
) and up signal (
CUD)
will
toggle when the count register increases on a rotation to the right. Upon
rotating to the left, both
CDG
and
CUD
will toggle, and the over all count
decreases.
If the processor pins are needed for the expansion interface, disconnect the
rotary encoder switch via the four-position rotary NAND enable switch
(
SW11
).
For more information, see “Rotary NAND Enable Switch
The
CDG
signal is shared with the
SPISEL2
signal; care must be taken not to
rotate the switch while issuing SPI commands to the keypad and touch-
screen controller. To ensure that there is no interference from the rotary
encoder on
SPISEL2
, turn
SW1
position 2
OFF
. Shutting off connection to
CDG
causes the rotary switch not to operate correctly. Both
CDG
and
CUD
are
necessary for the switch to output accurate counts.
An example program is included in the EZ-KIT Lite installation directory
to demonstrate how to setup and access the rotary encoder interface.
www.BDTIC.com/ADI
Summary of Contents for Lite ADSP-BF527 EZ-KIT
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