ADP5585CP-EVALZ Analog Devices, ADP5585CP-EVALZ Datasheet - Page 10

• Manufacturer Part Number: ADP5585CP-EVALZ
• Description: Interface Development Tools LFCSP Evaluation Board
• Manufacturer: Analog Devices
• Series: ADP5585r

Specifications of ADP5585CP-EVALZ

• Rohs: yes
• Product: Evaluation Boards
• Tool Is For Evaluation Of: ADP5585
• Interface Type: I2C
• Operating Supply Voltage: 1.8 V to 3 V
• Factory Pack Quantity: 1

ADP5585
Figure 9 shows a simplified representation of the key scan block
using three row and three column pins connected to a small 3 × 3,
nine-switch keypad matrix. When the key scanner is idle, the
row pins are pulled high and the column pins are driven low.
The key scanner operates by checking the row pins to see if they
are low.
If Switch 6 in the matrix is pressed, R1 connects to C2. The key
scan circuit senses that one of the row pins has been pulled low,
and a key scan cycle begins. Key scanning involves driving all
column pins high, then driving each column pin, one at a time,
C0
1
4
7
C1
Figure 9. Simplified Key Scan Block
2
5
8
C2
3
9
6
CONTROL
3 × 3 KEYPAD MATRIX
SCAN
KEY
RESET_TRIG_TIME[2:0]
RESET1_EVENT_A[7:0]
RESET1_EVENT_B[7:0]
RESET1_EVENT_C[7:0]
RESET2_EVENT_A[7:0]
RESET2_EVENT_B[7:0]
VDD
PIN_CONFIG_A[7:0]
PIN_CONFIG_B[7:0]
PIN_CONFIG_C[7:0]
31
32
33
34
35
36
R0
C0 C1 C2 C3 C4
11
16
21
26
6
1
12
17
22
27
R1
7
2
SINK ON/OFF
13
18
23
28
COLUMN
3
8
I/O CONFIGURATION
R2
14
19
24
29
9
Figure 11. Detailed Key Scan Block
4
KEY SCAN
CONTROL
10
15
20
25
30
5
Rev. C | Page 10 of 40
R0
SENSE
R1 R2
ROW
LOGIC EVENT
KEY EVENT
GPI EVENT
I
2
R3
C BUSY?
RESET 1_INITIATE
RESET 2_INITIATE
EVENT_INT
R4 R5
low and sensing whether a row pin is low or not. All row/column
pairs are scanned; therefore, if multiple keys are pressed, they
are detected.
To prevent glitches or narrow press times being registered as a
valid key press, the key scanner requires the key be pressed for
two scan cycles. The key scanner has a wait time between each
scan cycle; therefore, the key must be pressed and held for at
least this wait time to register as being pressed. If the key is
continuously pressed, the key scanner continues to scan, wait,
scan, wait, and so forth.
If Switch 6 is released, the connection between R1 and C2
breaks, and R1 is pulled up high. The key scanner requires that
the key be released for two scan cycles because the release of a
key is not necessarily in sync with the key scanner, it may take
up to two full wait/scan cycles for a key to register as released.
When the key is registered as released, and no other keys are
pressed, the key scanner returns to idle mode.
For the remainder of this document, the press/release status of a
key is represented as simply a logic signal in the figures. A logic
high level represents the key status as pressed, and a logic low
represents released. This eliminates the need to draw individual
row/column signals when describing key events.
Figure 11 shows a detailed representation of the key scan block
and its associated control and status signals. When all row and
column pins are used, a matrix of 25 unique keys can be
scanned.
KEY x
UPDATE
FIFO
KEY RELEASED
Figure 10. Logic Low: Released, Logic High: Pressed
OVRFLOW_INT
EC[4:0]
FIFO
KEY PRESSED
KEY RELEASED
Data Sheet