MC68HC908QY4CDW Datasheet, PDF (50/184 Pages) Freescale Semiconductor, Inc – Microcontrollers

Auto Wakeup Module (AWU)
COPRS (FROM CONFIG1)
AUTOWUGEN
SHORT
1 = DIV 2⁹
0 = DIV 2¹⁴
INT RC OSC
OVERFLOW
EN 32 kHz
CLK _RST
V_DD
D
Q
E
R
TO PTA READ, BIT 6
AWUL
AWUIREQ
TO KBI INTERRUPT LOGIC (SEE
Figure 9-2. Keyboard Interrupt
Block Diagram)
(CGMXCLK)
BUSCLKX4
CLRLOGIC
CLEAR
CLK
RST
RESET _ISTOP
RESET
ACKK
RESET
AWUIE
Figure 4-1. Auto Wakeup Interrupt Request Generation Logic
The auto wakeup RC oscillator is highly dependent on operating voltage and temperature. This feature is
not recommended for use as a time-keeping function.
The wakeup request is latched to allow the interrupt source identification. The latched value, AWUL, can
be read directly from the bit 6 position of PTA data register. This is a read-only bit which is occupying an
empty bit position on PTA. No PTA associated registers, such as PTA6 data, PTA6 direction, and PTA6
pullup exist for this bit. The latch can be cleared by writing to the ACKK bit in the KBSCR register. Reset
also clears the latch. AWUIE bit in KBI interrupt enable register (see Figure 4-1) has no effect on AWUL
reading.
The AWU oscillator and counters are inactive in normal operating mode and become active only upon
entering stop mode.
4.4 Wait Mode
The AWU module remains inactive in wait mode.
4.5 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.
MC68HC908QY/QT Family Data Sheet, Rev. 6
50
Freescale Semiconductor