MAX7365 Maxim, MAX7365 Datasheet - Page 8

• Manufacturer Part Number: MAX7365
• Description: The MAX7365 is an I²C-interfaced peripheral that provides microprocessors with management of up to 56 key switches
• Manufacturer: Maxim

Table 1. Register Address Map and Power-Up Condition (continued)
Table 2. Key-Switch Mapping
Key inputs are scanned statically, not dynamically, to
ensure low-EMI operation. Since inputs only toggle in
response to switch changes, the key matrix can be
routed closer to sensitive circuit nodes.
The keyscan controller debounces and maintains a FIFO
buffer of keypress and release events (including auto-
repeated keypresses, if autorepeat is enabled).
shows the key-switch order. The user-programmable
key-switch debounce time and autosleep timer are
derived from the clock, which in turn is derived from the
internal oscillator. Time delay for autorepeat and key-
switch interrupt is based on the key-switch debounce
time. There is no limitation for the number of keys pressed
simultaneously as long as no ghost keys are generated.
If the application requires fewer keys to be scanned, the
unused key-switch ports can be configured as GPIs.
CODE (hex)
ADDRESS
0x3D
0x40
0x42
0x48
ROW0
ROW1
ROW2
ROW3
ROW4
ROW5
ROW6
ROW7
PIN
WRITE
READ/
R/W
R/W
R/W
R/W
����������������������������������������������������������������� Maxim Integrated Products 8
KEY 0
KEY 1
KEY 2
KEY 3
KEY 4
KEY 5
KEY 6
KEY 7
COL0
VALUE (hex)
POWER-UP
Key-Switch Controller with GPIO Ports
0x00
0x00
0x00
0x00
Keyscan Controller
KEY 10
KEY 11
KEY 12
KEY 13
KEY 14
KEY 15
COL1
KEY 8
KEY 9
REGISTER FUNCTION
GPI Debounce Setting GPIO port inputs debounce time setting
GPO Pullup/Pulldown
I
Resistor Enable
2
C Timeout Flag
Configuration
GPIO Global
KEY 16
KEY 17
KEY 18
KEY 19
KEY 20
KEY 21
KEY 22
KEY 23
Table 2
COL2
1MHz I
GPIO port open-drain output mode pullup/pulldown resistor
setting
GPI autowake enable, I
mode
I
2
The Keys FIFO register contains the information pertain-
ing to the status of the keys FIFO, as well as the key
events that have been debounced
denote which of the 56 keys have been debounced, and
the keys are numbered as shown in
Special codes are key repeat (0x1E/0x3E), FIFO empty
(0x3F), and FIFO overflow (0x7F). Bit D7 indicates if there
is more data in the FIFO, except when a special key code
occurs. D6 indicates if a keypress or release event has
occurred.
Reading the keyscan FIFO clears the interrupt (INT),
depending on the setting of bit D5 in the configuration
register (0x01).
C timeout since last POR
KEY 24
KEY 25
KEY 26
KEY 27
KEY 28
KEY 29
KEY 30
KEY 31
COL3
2
C-Interfaced 8 x 7
KEY 32
KEY 33
KEY 34
KEY 35
KEY 36
KEY 37
KEY 38
KEY 39
COL4
2
C timeout interrupt enable, operating
DESCRIPTION
Keys FIFO Register (0x00)
KEY 40
KEY 41
KEY 42
KEY 43
KEY 44
KEY 45
KEY 46
KEY 47
COL5
MAX7365
(Table
Table
6). Bits D[5:0]
2.
KEY 48
KEY 49
KEY 50
KEY 51
KEY 52
KEY 53
KEY 54
KEY 55
COL6