ak4184a AKM Semiconductor, Inc., ak4184a Datasheet - Page 21

• Manufacturer Part Number: ak4184a
• Description: Tsc With Keypad Scanner And Gpio Expander
• Manufacturer: AKM Semiconductor, Inc.

■
The AK4184A has a keypad interface which supports maximum Keypad matrix of six columns by five rows.
■
Setting the KST1 bit = “0” (default) enables the AK4184A to monitor key-press detection and move to key pad
measurement mode after keypad detection. The AK4184A provides two different keypad measurement modes by
setting the KST0 bit: host scan mode and key press scan mode.
The keypad data register (KPDATA1, KPDATA2) is revised after completing a debounce scan. The KEYIQRN pin
goes to “H” and the AK4184A goes to hold state. Key press detect function is disabled during the hold time. When the
host processor reads the keypad data register during hold time, the hold time counter is reset and restarted after being
read by the host processor. Key press detection is not valid until the host processor reads the keypad data register after
hold time is passed. Reading a keypad date is determined by accessing KPDATA1, KPDATA2 register. Reading the
KPDATA1 or KPDATA2 registers is required when key press interrupts of the AK4184A become valid. The hold time
and the debounce time are controlled through the keypad control register (KEY).
MS0947-E-00
Keypad Scanner
Keypad Measurement Mode
■ Key press Scan Mode
When the KST0 bit is “1” the mode is host scan mode, pressing the keypad down makes the AK4184A outputs
a keypad interrupt signal (KEYIRQN pin goes low), and then the AK4184A move to the state which waits for
a KPScanInitiate (Page1, Address 04H) command from host. The internal oscillator turns off until receiving
this command, and the AK4184A does not execute key scan. Keypad scan begin when receiving a
KPScanInitiate command. Once receiving this command, the AK4184A turns on the internal oscillator and
starts keypad debounce scan.
When the KST0 bit is “0” key press scan mode is enabled. Pressing the keypad down causes the AK4184A to
output a keypad interrupt signal (KEYIRQN pin goes low) and the AK4184A starts a keypad debounce scan
automatically.
■ Host Scan Mode
KEYIRQN
CSN
DIN
DOUT
BUSY
State
Keypad Debounce Scan initiated by Host (Initial : KST1 bit="0", KST0 bit="1")
Ry
Figure 13. Timing Diagram for keypad debounce scan initiated by Host
Enable
Detect
Key
(Initial: key interrupt enable, wait for Host instruction)
wait
KPScanInitiate
Debounce
Scan
HOLD
- 21 -
Disable
Detect
Key
KPDATA1,2
Key Detect
KPScanInitiate
then wait
Enable
reset after keypad data is read completly.
when Host reads the keypad data during
the hold time, the hold time counter will
Debounce
Scan
KPDATA1,2
HOLD
[AK4184A]
2008/04