MC68HC908GT16 Datasheet, PDF (196/412 Pages) Motorola, Inc – Microcontrollers

Keyboard Interrupt Module (KBI)
13.3 Features
Features include:
• Eight keyboard interrupt pins with separate keyboard interrupt
enable bits and one keyboard interrupt mask
• Hysteresis buffers
• Programmable edge-only or edge- and level- interrupt sensitivity
• Exit from low-power modes
• I/O (input/output) port bit(s) software configurable with pullup
device(s) if configured as input port bit(s)
13.4 Functional Description
Writing to the KBIE7–KBIE0 bits in the keyboard interrupt enable register
independently enables or disables each port A pin as a keyboard
interrupt pin. Enabling a keyboard interrupt pin also enables its internal
pullup device. A logic 0 applied to an enabled keyboard interrupt pin
latches a keyboard interrupt request.
A keyboard interrupt is latched when one or more keyboard pins goes
low after all were high. The MODEK bit in the keyboard status and
control register controls the triggering mode of the keyboard interrupt.
• If the keyboard interrupt is edge-sensitive only, a falling edge on a
keyboard pin does not latch an interrupt request if another
keyboard pin is already low. To prevent losing an interrupt request
on one pin because another pin is still low, software can disable
the latter pin while it is low.
• If the keyboard interrupt is falling edge- and low-level sensitive, an
interrupt request is present as long as any keyboard interrupt pin
is low and the pin is keyboard interrupt enabled.
Technical Data
196
MC68HC908GT16 • MC68HC908GT8 — Rev. 2
Keyboard Interrupt Module (KBI)
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