MPC563XM Reference Manual, Rev. 1
Freescale Semiconductor
1311
Preliminary—Subject to Change Without Notice
when the module is in Disable Mode. Exiting from this mode is done by negating the MDIS bit, which will
resume the clocks and negate the LPM_ACK bit.
28.5.9.3
Doze Mode
This is a system low power mode in which the CPU bus is kept alive and a global Doze Mode request is
sent to all peripherals asking them to enter low power mode. When Doze Mode is globally requested, the
DOZE bit in MCR needs to have been asserted previously for Doze Mode to be triggered. If Doze Mode
is triggered during Freeze Mode, FlexCAN shuts down the clocks to the CPI and MBM sub-modules, sets
the LPM_ACK bit and negates the FRZ_ACK bit. If Doze Mode is triggered during transmission or
reception, FlexCAN does the following:
•
Waits to be in either Idle or Bus Off state, or else waits for the third bit of Intermission and checks
it to be recessive
•
Waits for all internal activities like arbitration, matching, move-in and move-out to finish
•
Ignores its Rx input pin and drives its Tx pin as recessive
•
Shuts down the clocks to the CPI and MBM sub-modules
•
Sets the NOT_RDY and LPM_ACK bits in MCR
The Bus Interface Unit continues to operate, enabling the CPU to access memory mapped registers, except
the Free Running Timer, the Error Counter Register and the Message Buffers, which can not be accessed
in Doze Mode.
Exiting Doze Mode is done in one of the following ways:
•
CPU removing the Doze Mode request
•
CPU negating the DOZE bit of the MCR Register
•
Self Wake mechanism
In the Self Wake mechanism, if the SLF_WAK bit in MCR Register was set at the time FlexCAN entered
Doze Mode, then upon detection of a recessive to dominant transition on the CAN bus, FlexCAN negates
the DOZE bit and resumes its clocks. It also sets the WAK_INT bit in the ESR Register and, if enabled by
the WAK_MSK bit in MCR, generates a Wake Up interrupt to the CPU. FlexCAN will then wait for 11
consecutive recessive bits to synchronize to the CAN bus. As a consequence, it will not receive the frame
that woke it up.
details the effect of SLF_WAK and WAK_MSK upon wake-up from Doze
Mode.
Table 28-11. Wake-up from Doze Mode
SLF_WAK
WAK_MSK
FlexCAN
Clocks
Enabled
Wake-up
Interrupt
Generated
0
0
No
No
0
1
No
No
1
0
Yes
No
1
1
Yes
Yes