NUC950ADN Datasheet, PDF (604/629 Pages) Nuvoton Technology Corporation – 32-BIT ARM926EJ-S BASED MCU

NUC950ADN
32-BIT ARM926EJ-S BASED MCU
7.19 Keypad Interface (KPI)
The Keypad Interface (KPI) is an APB slave with 4-row scan output and 8-column scan input. KPI scans
an array up to 16x8 with an external 4 to 16 decoder. It can also be programmed to scan 8x8 or 4x8 key
array. If the 4x8 array is selected then external decoder is not necessary because the scan signals are
driven by chip itself. Any 1 or 2 keys in the array that pressed are de-bounced and encoded. If more than
2 keys are pressed, only the keys or apparent keys in the array with the lowest address will be decoded.
The KPI supports 2-keys scan interrupt and specified 3-keys interrupt or chip reset. If the 3 pressed keys
matches with the 3 keys defined in KPI3KCONF, it will generate an interrupt or chip reset to nWDOG
reset output depend on the ENRST setting. The interrupt is generated whenever the scanner detects a
key is pressed and then after the key is released. The interrupt conditions are 1 key, or 2 keys and no
keys.
This chip provides one keypad connecting interface, which is allocated in GPIOC interface and shared with
NAND Flash Interface.
The keypad interface has the following features:
 maximum 16x8 array with an external 4 to 16 decoder
 programmable de-bounce time
 low-power wakeup mode for 4x8 array
 programmable three-key reset
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Publication Release Date: Jun. 18, 2010
Revision: A4