MAX7349AEG Maxim Integrated, MAX7349AEG Datasheet - Page 13

• Manufacturer Part Number: MAX7349AEG
• Description: Peripheral Drivers & Components - PCIs Low-EMI Key Switch & Sounder Controller
• Manufacturer: Maxim Integrated

Table 7. Key-Scan Register Address Map
Table 8. Keys FIFO Register Format
* Reading the key-scan FIFO clears the INT. INT is only reasserted by a key event after the FIFO has been emptied by read(s).
Address autoincrementing allows the MAX7347/
MAX7348/MAX7349 to be configured with fewer trans-
missions by minimizing the number of times the com-
mand address needs to be sent. The command
address stored in the MAX7347/MAX7348/MAX7349
generally increments after each data byte is written or
read (Table 4). Autoincrementing applies only to the
key-scan command addresses and not to the sounder
command addresses.
FIFO has not overflowed
FIFO overflowed; FIFO contains the first eight
key events
This key is the last FIFO item (key-switch data
not zero)
Key 0 was EITHER the last FIFO item OR the
FIFO is empty and no key has been pressed
This key is not the last FIFO item
Power-up default setting
Keys FIFO
Debounce
Autorepeat
Interrupt
Configuration
Ports
Key Sound
Alert Sound
REGISTER
FUNCTION
Command Address Autoincrementing
KEYS FIFO REGISTER*
REGISTER
______________________________________________________________________________________
2-Wire Interfaced Low-EMI Key Switch
D15
0
0
0
0
0
0
0
0
D14
0
0
0
0
0
0
0
0
ADDRESS
D13
0
0
0
0
0
0
0
0
CODE
(hex)
0X00
0x00
0x00
0x00
0x00
0x00
0x00
COMMAND ADDRESS
D12
0
0
0
0
0
0
0
0
OVERFLOW
and Sounder Controllers
FLAG
D7
On power-up, all control registers are reset and the
MAX7347/MAX7348/MAX7349 enter shutdown mode
(Tables 5, 6). Table 7 shows the register address map
for the key-scan section.
0
1
X
0
X
0
D11
0
0
0
0
0
0
0
0
MORE
FLAG
D6
X
X
0
0
1
0
D10
0
0
0
0
1
1
1
1
REGISTER DATA
D5
Registers Description
X
X
X
X
0
0
KEY SWITCH THAT HAS BEEN
D9
0
0
1
1
0
0
1
1
D4
X
X
X
X
0
0
DEBOUNCED
D3
X
X
X
0
X
0
Initial Power-Up
D8
0
1
0
1
0
1
0
1
D2
X
X
X
0
X
0
ADDRESS
D1
X
X
X
0
X
0
CODE
(hex)
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
D0
X
X
X
0
X
0
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