Figure 26-3. apparent key 00h -4 – Cirrus Logic EP93xx User Manual
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DS785UM1
Copyright 2007 Cirrus Logic
Keypad Interface
EP93xx User’s Guide
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•
No press for address 0x1B at (ROW3, COL3)
The ignored addresses, 0x18 and 0x1B, are greater than the addresses of the two keys
detected. The following controller actions occur:
•
ROW0 is driven low.
•
When ROW0 is low, COL0 and COL3 are also low due to the current paths formed by
the keys pressed.
•
During the time that ROW1 is low each of the columns (COL0 through COL7) is
scanned.
•
Since COL0 is low the key 0x00 appears to be pressed.
Figure 26-3. Apparent Key 00H
ROW 0
KEY 00H
KEY 01H
KEY 02H
KEY 03H
KEY 04H
KEY 05H
KEY 06H
KEY 07H
ROW 1
KEY 08H
KEY 09H
KEY 0AH
KEY 0BH
KEY 0CH
KEY 0DH
KEY 0EH
KEY 1FH
ROW 2
KEY 10H
KEY 11H
KEY 12H
KEY 13H
KEY 14H
KEY 15H
KEY 16H
KEY 17H
ROW 3
KEY 18H
KEY 19H
KEY 1AH
KEY 1BH
KEY 1CH
KEY 1DH
KEY 1EH
KEY 1FH
ROW 4
KEY 20H
KEY 21H
KEY 22H
KEY 23H
KEY 24H
KEY 25H
KEY 26H
KEY 27H
ROW 5
KEY 28H
KEY 29H
KEY 2AH
KEY 2BH
KEY 2CH
KEY 2DH
KEY 2EH
KEY 2FH
ROW 6
KEY 30H
KEY 31H
KEY 32H
KEY 33H
KEY 34H
KEY 35H
KEY 36H
KEY 37H
ROW 7
KEY 38H
KEY 39H
KEY 3AH
KEY 3BH
KEY 3CH
KEY 3DH
KEY 3EH
KEY 3FH
COL 0
COL 1
COL 2
COL 3
COL 4
COL 5
COL 6
COL 7