Datasheet

MSCAN
MC9S12DP256 — Revision 1.1
MSCAN
CPU Run Mode As can be seen in Table 94, only MSCAN Sleep Mode is available as low
power option, when CPU is in run mode.
CPU Wait Mode The WAI instruction puts the MCU in a low power consumption stand-by
mode. If the CSWAI bit is set, then additional power can be saved in
Power Down Mode since the CPU clocks are stopped. After leaving this
Power Down Mode the MSCAN restarts its internal controllers and
enters Normal Mode again
While the CPU is in Wait Mode, the MSCAN can be operated in Normal
Mode and generate interrupts (registers can be accessed via
background debug mode). The MSCAN can also operate in any of the
low power modes depending on the values of the SLPRQ/SLPAK and
CSWAI bits as seen in Table 94.
Stop Mode The STOP instruction puts the MCU in a low power consumption
stand-by mode. In Stop mode, the MSCAN operates in Power Down
mode regardless of the value of the SLPRQ/SLPAK and CSWAI bits
(see CPU vs. MSCAN Operating Modes).
MSCAN Sleep
Mode
The CPU can request the MSCAN to enter this low power mode by
asserting the SLPRQ bit in the CANCTL0 register. The time when the
MSCAN enters Sleep Mode depends on a fixed synchronisation delay
and its current activity:
• If it is transmitting, it continues to transmit until the entire message
is transmitted and then goes into Sleep Mode.
• If it is receiving, it waits for the end of this message and then goes
into Sleep Mode.
• If it is neither transmitting nor receiving, it immediately goes into
Sleep Mode.
Freescale Semiconductor, I
Freescale Semiconductor, Inc.
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