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Power Management
MCF52235 ColdFire® Integrated Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor
9-13
9.4.2.4
System Control Module (SCM)
The SCM’s core watchdog timer can bring the device out of all low-power modes except stop mode. In
stop mode, all clocks stop, and the core watchdog does not operate.
When enabled, the core watchdog can bring the device out of wait and doze modes via a core watchdog
interrupt. This system setup must meet the conditions specified in
Section 9.4.1, “Low-Power Modes
” for
the core watchdog interrupt to bring the part out of wait and doze modes.
9.4.2.5
DMA Controller (DMA0–DMA3)
In wait and doze modes, the DMA controller is capable of bringing the device out of a low-power mode
by generating an interrupt upon completion of a transfer or upon an error condition. The completion of
transfer interrupt is generated when DMA interrupts are enabled by the setting of the DCR[INT] bit, and
an interrupt is generated when the DSR[DONE] bit is set. The interrupt upon error condition is generated
when the DCR[INT] bit is set, and an interrupt is generated when the CE, BES, or BED bit in the DSR
becomes set.
The DMA controller is stopped in stop mode and thus cannot cause an exit from this low-power mode.
9.4.2.6
UART Modules (UART0, UART1, and UART2)
In wait and doze modes, the UART may generate an interrupt to exit the low-power modes.
•
Clearing the transmit enable bit (TE) or the receiver enable bit (RE) disables UART functions.
•
The UARTs are unaffected by wait mode and may generate an interrupt to exit this mode.
In stop mode, the UARTs stop immediately and freeze their operation, register values, state machines, and
external pins. During this mode, the UART clocks are shut down. Coming out of stop mode returns the
UARTs to operation from the state prior to the low-power mode entry.
9.4.2.7
I
2
C Module
When the I
2
C Module is enabled by the setting of the I2CR[IEN] bit and when the device is not in stop
mode, the I
2
C module is operable and may generate an interrupt to bring the device out of a low-power
mode. For an interrupt to occur, the I2CR[IIE] bit must be set to enable interrupts, and the setting of the
I2SR[IIF] generates the interrupt signal to the CPU and interrupt controller. The setting of I2SR[IIF]
signifies the completion of one byte transfer or the reception of a calling address matching its own
specified address when in slave receive mode.
In stop mode, the I
2
C Module stops immediately and freezes operation, register values, and external pins.
Upon exiting stop mode, the I
2
C resumes operation unless stop mode was exited by reset.
9.4.2.8
Queued Serial Peripheral Interface (QSPI)
In wait and doze modes, the queued serial peripheral interface (QSPI) may generate an interrupt to exit the
low-power modes.
•
Clearing the QSPI enable bit (SPE) disables the QSPI function.
•
The QSPI is unaffected by wait mode and may generate an interrupt to exit this mode.
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