MC68HC908GR16 Datasheet, PDF (113/310 Pages) Motorola, Inc – Microcontrollers

Freescale Semiconductor, Inc.
Keyboard Interrupt Module (KBI)
Low-Power Modes
Another way to avoid a false interrupt:
1. Configure the keyboard pins as outputs by setting the appropriate DDRA
bits in data direction register A.
2. Write logic 1s to the appropriate port A data register bits.
3. Enable the KBI pins by setting the appropriate KBIEx bits in the keyboard
interrupt enable register.
9.5 Low-Power Modes
The WAIT and STOP instructions put the microcontroller unit (MCU) in low
power-consumption standby modes.
9.5.1 Wait Mode
The keyboard module remains active in wait mode. Clearing the IMASKK bit in the
keyboard status and control register enables keyboard interrupt requests to bring
the MCU out of wait mode.
9.5.2 Stop Mode
The keyboard module remains active in stop mode. Clearing the IMASKK bit in the
keyboard status and control register enables keyboard interrupt requests to bring
the MCU out of stop mode.
9.6 Keyboard Module During Break Interrupts
The system integration module (SIM) controls whether the keyboard interrupt latch
can be cleared during the break state. The BCFE bit in the break flag control
register (BFCR) enables software to clear status bits during the break state.
To allow software to clear the keyboard interrupt latch during a break interrupt,
write a logic 1 to the BCFE bit. If a latch is cleared during the break state, it remains
cleared when the MCU exits the break state.
To protect the latch during the break state, write a logic 0 to the BCFE bit. With
BCFE at logic 0 (its default state), writing to the keyboard acknowledge bit (ACKK)
in the keyboard status and control register during the break state has no effect. See
9.7.1 Keyboard Status and Control Register.
MC68HC908GR16 — Rev. 1.0
MOTOROLA
Keyboard Interrupt Module (KBI)
For More Information On This Product,
Go to: www.freescale.com
Data Sheet
113