Cirrus Logic EP93xx User Manual
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DS785UM1
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Copyright 2007 Cirrus Logic
Keypad Interface
EP93xx User’s Guide
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Address:
0x808F_0000
Default:
0x0000_0000
Definition:
Key scan initialization register.
Bit Descriptions:
RSVD:
Reserved. Unknown during read.
DBNC:
De-bounce start count. This value is used to pre-load the
de-bounce counter. The de-bounce counter counts the
number of consecutive scans that decoded the same
keys. Terminal count for the de-bounce counter is 0xFF.
Terminal count indirectly generates a key scan interrupt. A
pre-load value of 0xFC will cause the key scan circuitry to
count 3 identical consecutive keypad scans.
DIS3KY:
Disable 3 Key reset. Setting this bit high disables the three
key reset output to the watchdog reset block. Setting it
back low re-enables it.
DIAG:
Key scan diagnostic mode. Setting this bit high allows key
scanning to be directly controlled through the key register
by writes from the ARM Core. The DIAG.KEY[5:0] value is
written by the ARM Core. Then the KeyRegister.K bit is
read to determine if there is a key press. The result from
reading the KeyRegister.K bit is not hardware de-bounced.
BACK:
Key scan back driving enable. Setting this bit high enables
the key scanning logic to back drive the row and column
pins of the chip high during the first two column counts in
the row/column counter.
T2:
Test mode bit. When this bit is set to “1”, the counter
RC_COUNT is advanced by 8 counts when EN is active.
The effect is that only column 0 is checked in each row.
This test mode allows a faster test of the ROW pins.
NA:
Not Assigned. These bits will read back the value written.