ADP5587_1 AD [Analog Devices], ADP5587_1 Datasheet - Page 10

• Manufacturer Part Number: ADP5587_1
• Description: Mobile I/O Expander and QWERTY Keypad Controller
• Manufacturer: AD [Analog Devices]

ADP5587
Auto-Increment
The ADP5587 features automatic increment during I
access, which allows the user to increment the address pointer
without the need to send a read command for subsequent
addresses. This minimizes processor intervention and, therefore,
saves processor bandwidth and current drain. Bit 7 of Register 0x01
must be set to initiate auto-increment (see Figure 17 for the full
write and read sequence).
Key Event Interrupt
On a key event (KE) interrupt, the processor reads the interrupt
status register to determine the cause of the interrupt. If the
KE_INT bit in Register 0x02 is set, the processor reads the key
event count from the KEC [3:0] field in Register 0x03 to determine
the number of events. After reading all the events from the
NO
KEY PRESS
DETECTED
YES
START UNLOCK1 TO UNLOCK2
YES
YES
NO
NO
Figure 12. Keypad Lock Interrupt Mask Timer Flowchart
KEYLOCK INTERRUPT
START MASK TIMER
SECOND UNLOCK
KEY DETECTED
KEY DETECTED
TIMER EXPIRES
KE INTERRUPT
FIRST UNLOCK
MASK TIMER
UNLOCK1 TO
MASK TIMER
GENERATE
GENERATE
UNLOCK2
YES
2
EXPIRES
EXPIRES
C read
NO
YES
YES
NO
NO
NO
MASK TIMER = 0
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START
FIFO, it then reads the KEC field again (in Register 0x03) to
make sure that no new events have come in. After all the events
are read, the KEC field is decremented to zero (KEC = 0), and
the KE_INT bit can be cleared by writing a 1 to it. Both key
presses and key releases are capable of generating key event
interrupts. The KE_INT bit cannot be cleared, and the INT pin
cannot be deasserted, until the FIFO is cleared of all events.
YES
READ KE(s) TO CLEAR
THROUGH REG. 0x1F
START UNLOCK1 TO UNLOCK2
KEYPAD MODE
KEYLOCK INTERRUPT
REG. 0x1D
REG. 0x01
REG. 0x03
KE_IEN
SECOND UNLOCK
KEY DETECTED
KEC
TIMER EXPIRES
KEY DETECTED
FIRST UNLOCK
UNLOCK1 TO
KEY PRESS
DETECTED
GENERATE
UNLOCK2
Figure 11. Key Event Interrupt Generation
YES
YES
YES
NO
WRITE 1 TO CLEAR
NO
NO
REG. 0x02
KE_INT
NO
YES
AND
INT DRIVE