TCA8418 Datasheet, PDF (16/37 Pages) Texas Instruments – I2C CONTROLLED KEYPAD SCAN IC WITH INTEGRATED ESD PROTECTION

TCA8418
SCPS215 – SEPTEMBER 2009 ......................................................................................................................................................................................... www.ti.com
BIT
NAME
DESCRIPTION
Key events interrupt enable to host processor
0
KE_IEN
0 = disabled
1 = enabled Can be used to mask interrupts
Bit 7 in this register is used to determine the programming mode. If it is low, all data bytes are written to the
registers defined command byte. If bit 7 is high, the value of the command byte is automatically incremented
after the byte is written, and the next data byte is stored in the corresponding register. Registers are written in
the sequence shown in Table 3. Once the GPIO_PULL3 register (0×2E) is written to, the command byte returns
to 0 (Configuration register). Registers 0 and 2F are reserved and a command byte that references these
registers is not acknowledged by the TCA8418E.
The keypad lock interrupt enable determines if the interrupt pin is asserted when the key lock interrupt (see
Interrupt Status Register) bit is set.
Interrupt Status Register, INT_STAT (Address 0×02)
BIT
NAME
7
N/A
Always 0
6
N/A
Always 0
5
N/A
Always 0
DESCRIPTION
CTRL-ALT-DEL key sequence status. Requires writing a 1 to clear interrupts.
4
CAD_INT
0 = interrupt not detected
1 = interrupt detected
Overflow interrupt status. Requires writing a 1 to clear interrupts.
3
OVR_FLOW_INT
0 = interrupt not detected
1 = interrupt detected
Keypad lock interrupt status. This is the interrupt to the processor when the keypad lock
sequence is started. Requires writing a 1 to clear interrupts.
2
K_LCK_INT
0 = interrupt not detected
1 = interrupt detected
GPI interrupt status. Requires writing a 1 to clear interrupts.
1
GPI_INT
0 = interrupt not detected
1 = interrupt detected
Can be used to mask interrupts
Key events interrupt status. Requires writing a 1 to clear interrupts.
0
K_INT
0 = interrupt not detected
1 = interrupt detected
Key Lock and Event Counter Register, KEY_LCK_EC (Address 0×03)
BIT
NAME
7
N/A
Always 0
DESCRIPTION
Key lock enable
6
K_LCK_EN
0 = disabled
1 = enabled
Keypad lock status
5
LCK2
0 = unlock (if LCK1 is 0 too)
1 = locked (if LCK1 is 1 too)
Keypad lock status
4
LCK1
0 = unlock (if LCK2 is 0 too)
1 = locked (if LCK2 is 1 too)
3
KEC3
Key event count, Bit 3
2
KEC2
Key event count, Bit 2
16
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