XC912BC32CFU8 Motorola Semiconductor Products, XC912BC32CFU8 Datasheet - Page 273

• Manufacturer Part Number: XC912BC32CFU8
• Description: M68HC12B Family Data Sheet
• Manufacturer: Motorola Semiconductor Products

16.7 Low-Power Modes
16.7.1 msCAN12 Sleep Mode
M68HC12B Family — Rev. 8.0
MOTOROLA
In addition to normal mode, the msCAN12 has three modes with reduced power
consumption compared to normal mode. In sleep and soft-reset mode, power
consumption is reduced by stopping all clocks except those to access the registers.
In power-down mode, all clocks are stopped and no power is consumed.
The wait-for-interrupt (WAI) and STOP instructions put the MCU in low
power-consumption standby modes.
msCAN12 and CPU modes. A particular combination of modes is entered for the
given settings of the bits CSWAI, SLPAK, and SFTRES. For all modes, an msCAN
wakeup interrupt can occur only if SLPAK = WUPIE = 1. While the CPU is in wait
mode, the msCAN12 can be operated in normal mode and emit interrupts.
(Registers can be accessed via background debug mode.)
The CPU can request the msCAN12 to enter this low-power mode by asserting the
SLPRQ bit in the module configuration register. See
The time when the msCAN12 enters sleep mode depends on its activity. For
instance,
Power-down
Sleep
Soft reset
Normal
1. X means don’t care.
•
•
•
msCAN
If it is transmitting, it continues to transmit until there are no more messages
to be 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.
Mode
Table 16-2. msCAN12 versus CPU Operating Modes
msCAN12 Controller
CSWAI = X
SFTRES = X
SLPAK = X
Stop
(1)
Table 16-2
SFTRES = X
SFTRES = 0
SFTRES = 1
SFTRES = 0
CPU Mode
CSWAI = 1
SLPAK = X
CSWAI = 0
CSWAI = 0
CSWAI = 0
SLPAK = 1
SLPAK = 0
SLPAK = 0
Wait
summarizes the combinations of
Figure
16-6.
msCAN12 Controller
SFTRES = 0
SFTRES = 1
SFTRES = 0
CSWAI = X
CSWAI = X
CSWAI = X
SLPAK = 1
SLPAK = 0
SLPAK = 0
Low-Power Modes
Run
Data Sheet
273