MC68LC302 Datasheet, PDF (30/169 Pages) Motorola, Inc – Low Power Integrated Multiprotocol Processor Reference Manual

Configuration, Clocking, Low Power Modes, and Internal Memory Map
an interrupt of higher level than the mask is asserted to the core, this process will
abort.
4. Wait for 16 clocks to guarantee the execution of the STOP command by the core. BG
and BGACK will reset the 16-clock counter and it will restart its count.
5. Assert bus request signal to the core.
6. Wait for Bus Grant from the core
7. Force the IMP to the selected power-down mode, as defined in Table 2-3.
2.4.4.2.3 IMP Wake-Up from Low Power STOP Modes. The IMP can wake up from
STOP/DOZE/STAND_BY mode to NORMAL/SLOW_GO mode in response to inputs from
the following sources:
1. Asserting both RESET and HALT (hard reset) pins.
2. Asserting (high to low transition) either PB9 or PB10 pins (if these interrupts are en-
abled).
3. A timeout of the periodic interrupt timer (if the PIT interrupt is enabled).
When one of these events occur (and the corresponding event bit is set), the IMP low power
controller will asynchronously restart the IMP clocks. Then IMP low power control logic will
release the 68000 bus and the IMP will return to normal operation. If one of the above wake-
up events occurs during the execution of the STOP command, the low power control logic
will abort the power down sequence and return to normal operation.
NOTE
The RI/PB9, DTE/PB10, and periodic interrupt timer timeout in-
terrupts conditions will generate level 4 interrupts.The user
should also set the 68000 interrupt mask in the status register
(SR) to the appropriate level before executing the STOP com-
mand to ensure that the IMP will wake up to the desired events.
2.4.4.2.4 IMP Wake-Up Control Register (IWUCR). The IWUCR contains control for the
wake-up options. This register can be read and written by the 68000 core.
IWUCR
7
6
5
4
3
0
PITE
PB10E
PB9Ev
0
RESET:
0
0
0
0
0
2
PITEn
0
1
PB10En
0
$0F7
0
PB9En
0
Read/Write
PB9Ev—PB9 Event
This bit will be set to one when there is a high to low transition on the PB9 pin. When
PB9En is set and PB9Ev is set, the IMP will wake-up from the selected power down state,
and a PB9 Interrupt will be generated. The IMP cannot enter the power-down mode if
MOTOROLA
MC68LC302 REFERENCE MANUAL
2-17