ak4184a AKM Semiconductor, Inc., ak4184a Datasheet - Page 12

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

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The AK4184A keypad scanner is designed to interface to a matrix type keypad with 5 rows x 6 columns (30keys or
fewer) to the host controller. The KPMASK1, 2 and KPColumnMask register enable the masking of certain keys or a
whole column of the keypad when any keys less than 30 keys or any columns less than 6 columns are not utilized.
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When the AK4184A is in key interrupt enabled mode, C1 ~ C6 pins are designed to output “H” and R1 ~ R5 pins are
designed to pull to GND via Rkey (Rkey=16kΩ typ,
and the KEYIRQN pin goes “L”. The KEYIRQN pin returns “H” after key press scan is completed. The KEYIRQN
pin does not go “L” again until the host reads the keypad read register (KPDATA1 or KPDATA2).
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The AK4184A starts scanning key condition in sequence and writes each keypad state to the registers after a key-
press is detected. First the C1 pin goes to “H” (Scan Output1) and the C2 ~ C6 pins are in Hi-Z state. Certain R1 ~ R5
pins are connected to C1 and pulled “H”. The R1 ~ R5 pins return to “L” after the key-press is released. The
AK4184A reads R1 ~ R5 pins level (Sense Input 1 through 5) and loads the keypad data into the register. When two
keys are pressed simultaneously, the associated row pins go “H” at the same time. Then the AK4184A C2 pin goes to
“H” (Scan Output2), and reads and loads the R1 ~ R5 pin levels into the register (Sense Input 1 through 5). The same
sequence as Scan Output 1 repeats up to Scan Output 6. The AK4184A makes this Scan Output and Sense Input
pattern and loads the keypad-data into the register for unmasked columns.
Debounce key scan performs a series of the Scan Output/ Sense Input at the end of the debounce time interval, then
the AK4184A loads the key pad data into the resister. μ-Processor starts to read the data register after confirming if
the keypad scan completed. New keypad scan does not repeat again until the Host reads the keypad data.
MS0947-E-00
Keypad Scanner
Keypad Interrupt Detection
Keypad Scan Data Read
Figure 5
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). When a key is pressed a related R1 ~ R5 pins go to “H”
[AK4184A]
2008/04