Freescale Semiconductor, Inc.
MSCAN Controller
Low Power Modes
NOTE: The MCU cannot clear the SLPRQ bit before the msCAN12 is in Sleep
Mode (SLPAK = 1).
After wake-up, the msCAN12 waits for 11 consecutive recessive bits to
synchronize to the bus. As a consequence, if the msCAN12 is woken-up
by a CAN frame, this frame is not received. The receive message buffers
(RxBG and RxFG) contain messages if they were received before sleep
mode was entered. All pending actions are executed upon wake-up:
copying of RxBG into RxFG, message aborts and message
transmissions. If the msCAN12 is still in bus-off state after leaving Sleep
Mode, it continues counting the 128*11 consecutive recessive bits.
msCAN12 Running
SLPRQ = 0
SLPAK = 0
MCU
MCU
or msCAN12
msCAN12 Sleeping
SLEEP Request
SLPRQ = 1
SLPAK = 1
SLPRQ = 1
SLPAK = 0
msCAN12
Figure 17-6. SLEEP Request / Acknowledge Cycle
17.8.2 msCAN12 SOFT_RESET Mode
In SOFT_RESET mode, the msCAN12 is stopped. Registers can still be
accessed. This mode is used to initialize the module configuration, bit
timing, and the CAN message filter. See msCAN12 Module Control
Register 0 (CMCR0) for a complete description of the SOFT_RESET
mode.
MC68HC912DG128 — Rev 3.0
Technical Data
MSCAN Controller
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