MC68HC908QY4A_10 Datasheet, PDF (53/200 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

Low-Power Modes
4.5 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-consumption standby modes.
4.5.1 Wait Mode
The AWU module is inactive in wait mode.
4.5.2 Stop Mode
When the AWU module is enabled (AWUIE = 1 in the keyboard interrupt enable register) it is activated
automatically upon entering 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. The AWU counters start
from 0 each time stop mode is entered.
4.6 Registers
The AWU shares registers with the keyboard interrupt (KBI) module, the port A I/O module and
configuration register 2. The following I/O registers control and monitor operation of the AWU:
• Port A data register (PTA)
• Keyboard interrupt status and control register (KBSCR)
• Keyboard interrupt enable register (KBIER)
• Configuration register 1 (CONFIG1)
• Configuration register 2 (CONFIG2)
4.6.1 Port A I/O Register
The port A data register (PTA) contains a data latch for the state of the AWU interrupt request, in addition
to the data latches for port A.
Bit 7
6
5
Read: 0
Write:
AWUL
PTA5
Reset: 0
0
= Unimplemented
4
PTA4
3
PTA3
2
PTA2
Unaffected by reset
1
PTA1
Bit 0
PTA0
Figure 4-2. Port A Data Register (PTA)
AWUL — Auto Wakeup Latch
This is a read-only bit which has the value of the auto wakeup interrupt request latch. The wakeup
request signal is generated internally. There is no PTA6 port or any of the associated bits such as
PTA6 data direction or pullup bits.
1 = Auto wakeup interrupt request is pending
0 = Auto wakeup interrupt request is not pending
NOTE
PTA5–PTA0 bits are not used in conjuction with the auto wakeup feature.
To see a description of these bits, see 12.3.1 Port A Data Register.
MC68HC908QYA/QTA Family Data Sheet, Rev. 3
Freescale Semiconductor
53