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FlexCAN Module
MPC5644A Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor
1405
FRZACK
Freeze Mode Acknowledge
This read-only bit indicates that FlexCAN is in Freeze Mode and its prescaler is stopped. The
Freeze Mode request cannot be granted until current transmission or reception processes have
finished. Therefore the software can poll the FRZACK bit to know when FlexCAN has actually
entered Freeze Mode. If Freeze Mode request is negated, then this bit is negated once the
FlexCAN prescaler is running again. If Freeze Mode is requested while FlexCAN is in any of the
low power modes, then the FRZACK bit will only be set when the low power mode is exited. See
for more information.
1: FlexCAN in Freeze Mode, prescaler stopped
0: FlexCAN not in Freeze Mode, prescaler running
SUPV
Supervisor Mode
This bit configures some of the FlexCAN registers to be either in Supervisor or Unrestricted
memory space. The registers affected by this bit are marked as S/U in the Access Type column of
. Reset value of this bit is ‘1’, so the affected registers start with Supervisor access
restrictions.
1: Affected registers are in Supervisor memory space. Any access without supervisor permission
behaves as though the access was done to an unimplemented register location
0: Affected registers are in Unrestricted memory space
SLF_WAK
Self Wake Up
This bit enables the Self Wake Up feature when FlexCAN is in Stop Mode. If this bit had been
asserted by the time FlexCAN entered Stop Mode, then FlexCAN will look for a recessive to
dominant transition on the bus during these modes. If a transition from recessive to dominant is
detected during Stop Mode, then FlexCAN generates, if enabled to do so, a Wake Up interrupt to
the CPU so that it can resume the clocks globally. This bit can not be written while the module is
in Stop Mode.
1: FlexCAN Self Wake Up feature is enabled
0: FlexCAN Self Wake Up feature is disabled
WRNEN
Warning Interrupt Enable
When asserted, this bit enables the generation of the TWRNINT and RWRNINT flags in the Error
and Status Register. If WRNEN is negated, the TWRNINT and RWRNINT flags will always be
zero, independent of the values of the error counters, and no warning interrupt will ever be
generated.
1: TWRNINT and RWRNINT bits are set when the respective error counter transition from <96 to
96.
0: TWRNINT and RWRNINT bits are zero, independent of the values in the error counters.
MDISACK
Low Power Mode Acknowledge
This read-only bit indicates that FlexCAN is either in Disable Mode or Stop Mode. Either of these
low power modes can not be entered until all current transmission or reception processes have
finished, so the CPU can poll the MDISACK bit to know when FlexCAN has actually entered low
power mode. See
Section 32.5.9.2, Module Disable Mode
and
for
more information.
1: FlexCAN is either in Disable Mode or Stop mode
0: FlexCAN not in any of the low power modes
Table 32-8. Module Configuration Register (MCR) field descriptions
Field
Description
Summary of Contents for MPC5644A
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