Low-Power Modes
18.6 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-consumption standby modes.
18.6.1 Wait Mode
The keyboard interrupt 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.
18.6.2 Stop Mode
The keyboard interrupt 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.
18.7 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 SIM 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.
MC68HC908AP Family Data Sheet, Rev. 4
Freescale Semiconductor
281
FREESCALE [ Freescale ]
