Power Management
MCF52235 ColdFire® Integrated Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor
9-11
9.4
Functional Description
The functions and characteristics of the low-power modes, and how each module is affected by, or affects
these modes are discussed in this section.
9.4.1
Low-Power Modes
The system enters a low-power mode by executing a STOP instruction. Which mode the device actually
enters (stop, wait, or doze) depends on what is programmed in LPCR[LPMD]. Entry into any of these
modes idles the CPU with no cycles active, powers down the system and stops all internal clocks
appropriately. During stop mode, the system clock is stopped low.
For entry into stop mode, the LPICR[ENBSTOP] bit must be set before a STOP instruction is issued.
A wakeup event is required to exit a low-power mode and return to run mode. Wakeup events consist of
any of these conditions:
•
Any type of reset
•
Any valid, enabled interrupt request
Exiting from low power mode via an interrupt request requires:
•
An interrupt request whose priority is higher than the value programmed in the XLPM_IPL field
of the LPICR.
•
An interrupt request whose priority higher than the value programmed in the interrupt priority
mask (I) field of the core’s status register.
•
An interrupt request from a source which is not masked in the interrupt controller’s interrupt mask
register.
•
An interrupt request which has been enabled at the module of the interrupt’s origin.
9.4.1.1
Run Mode
Run mode is the normal system operating mode. Current consumption in this mode is related directly to
the system clock frequency.
Table 9-10. PLL/CLKOUT Stop Mode Operation
STPMD[1:0]
Operation During Stop Mode
System Clocks
CLKOUT
PLL
OSC
PMM
00
Disabled
Enabled
Enabled
Enabled
Enabled
01
Disabled
Disabled
Enabled
Enabled
Enabled
10
Disabled
Disabled
Disabled
Enabled
Enabled
11
Disabled
Disabled
Disabled
Disabled
Low-Power Option
Because
of
an
order
from
the
United
States
International
Trade
Commission,
BGA-packaged
product
lines
and
part
numbers
indicated
here
currently
are
not
available
from
Freescale
for
import
or
sale
in
the
United
States
prior
to
September
2010:MCF52234CVM60,
MCF52235CVM60