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lasts until the next recessive to dominant edge, which re-synchronizes the FlexCAN back
to conform to the protocol. The same holds for auto-power save mode upon wake-up by
recessive to dominant edge.
The auto-power save mode in the FlexCAN is intended to enable NORMAL operation with
optimized power saving. Upon setting the AUTO POWER SAVE bit in the MCR register,
the FlexCAN looks for a set of conditions in which there is no need for clocks to run. If all
these conditions are met, then the FlexCAN stops its clocks, thus saving power. While its
clocks are stopped, if any of the conditions below is not met, the FlexCAN resumes its
clocks. It then continues to monitor the conditions and stops/resumes its clocks
appropriately.
The following are conditions for the automatic shut-off of FlexCAN clocks:
• No Rx/Tx frame in progress.
• No moving of Rx/Tx frames between SMB and MB and no Tx frame is pending for
transmission in any MB.
• No host access to the FlexCAN module.
• The FlexCAN is neither in halt mode (MCR bit 8), in stop mode (MCT bit 15), nor
in BUSOFF.
7.3.2.24 ColdFire Flash Module
The ColdFire Flash Control Module is capable of generating interrupts by the setting of the
CBEIF or CCIF bits in the CFMUSTAT. These interrupt sources, however, should not occur
when the device is in a low-power mode as long as no Flash operation was in progress when
the low-power mode was entered.
When performing a program or erase operation on the Flash, if a command is active (CCIF
= 0) when the MCU enters a low-power mode, the command sequence monitor will
perform the following:
1. The command in progress will be aborted.
2. The Flash high voltage circuitry will be switched off and any pending command
(CBEIF = 0) will not be executed when the MCU exits low-power mode.
3. The CCIF and ACCERR flags will be set if a command is active when the MCU
enters low-power mode.
The state of any longword(s) being programmed, or any erase
pages/physical blocks being erased, is not guaranteed if the
MCU enters stop mode with a command in progress. Active
commands are immediately aborted when the MCU enters stop
mode. Do not execute the STOP instruction during program
and erase operations.
MOTOROLA
NOTE
Chapter 7. Power Management
Functional Description
7-15
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