MC68HC08LT8 Datasheet, PDF (115/156 Pages) Freescale Semiconductor, Inc – Microcontrollers

Low-Power Modes
11.5.2 Keyboard Interrupt Enable Register
The port-A keyboard interrupt enable register enables or disables each port-A pin to operate as a
keyboard interrupt pin.
Address: $001C
Bit 7
6
5
4
3
2
1
Read: 0
0
0
0
KBIE3 KBIE2 KBIE1
Write:
Reset: 0
0
0
0
0
0
0
Figure 11-4. Keyboard Interrupt Enable Register (KBIER)
Bit 0
KBIE0
0
KBIE3–KBIE0 — Port-A Keyboard Interrupt Enable Bits
Each of these read/write bits enables the corresponding keyboard interrupt pin on port-A to latch
interrupt requests. Reset clears the keyboard interrupt enable register.
1 = KBIx pin enabled as keyboard interrupt pin
0 = KBIx pin not enabled as keyboard interrupt pin
11.6 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-consumption standby modes.
11.6.1 Wait Mode
The keyboard modules remain 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.
11.6.2 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.
11.7 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 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.
MC68HC08LT8 Data Sheet, Rev. 1
Freescale Semiconductor
115