Freescale’s Scalable Controller Area Network (S12MSCANV3)
Table 8-38. CPU vs. MSCAN Operating Modes
MSCAN Mode
Reduced Power Consumption
CPU Mode
Normal
Disabled
(CANE=0)
Sleep
Power Down
CSWAI = X(1)
SLPRQ = 0
SLPAK = 0
CSWAI = X
SLPRQ = 1
SLPAK = 1
CSWAI = X
SLPRQ = X
SLPAK = X
RUN
CSWAI = 0
SLPRQ = 0
SLPAK = 0
CSWAI = 0
SLPRQ = 1
SLPAK = 1
CSWAI = 1
SLPRQ = X
SLPAK = X
CSWAI = X
SLPRQ = X
SLPAK = X
WAIT
CSWAI = X
SLPRQ = X
SLPAK = X
CSWAI = X
SLPRQ = X
SLPAK = X
STOP
1. ‘X’ means don’t care.
8.4.5.1
Operation in Run Mode
As shown in Table 8-38, only MSCAN sleep mode is available as low power option when the CPU is in
run mode.
8.4.5.2
Operation in Wait Mode
The WAI instruction puts the MCU in a low power consumption stand-by mode. If the CSWAI bit is set,
additional power can be saved in power down mode because the CPU clocks are stopped. After leaving
this power down mode, the MSCAN restarts 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).
8.4.5.3
Operation in Stop Mode
The STOP instruction puts the MCU in a low power consumption stand-by mode. In stop mode, the
MSCAN is set in power down mode regardless of the value of the SLPRQ/SLPAK and CSWAI bits
(Table 8-38).
8.4.5.4
MSCAN Normal Mode
This is a non-power-saving mode. Enabling the MSCAN puts the module from disabled mode into normal
mode. In this mode the module can either be in initialization mode or out of initialization mode. See
Section 8.4.4.5, “MSCAN Initialization Mode”.
S12P-Family Reference Manual, Rev. 1.13
298
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