Freescale Semiconductor, Inc.
MSCAN Controller
NOTE: When setting the SFTRES bit, the msCAN12 immediately stops all
ongoing transmissions and receptions, potentially causing the CAN
protocol violations. The user is responsiblefor ensuring that the
msCAN12 is not active when SOFT_RESET mode is entered. The
recommended procedure is to bring the msCAN12 into SLEEP mode
before the SFTRES bit is set.
17.8.3 msCAN12 POWER_DOWN Mode
The msCAN12 is in POWER_DOWN mode when
• the CPU is in STOP mode or
• the CPU is in WAIT mode and the CSWAI bit is set (see msCAN12
Module Control Register 0 (CMCR0)).
When entering the POWER_DOWN mode, the msCAN12 immediately
stops all ongoing transmissions and receptions, potentially causing CAN
protocol violations.
NOTE: The user is responsible to take care that the msCAN12 is not active
when POWER_DOWN mode is entered. The recommended procedure
is to bring the msCAN12 into SLEEP mode before the STOP instruction
(or the WAI instruction, if CSWAI is set) is executed.
To protect the CAN bus system from fatal consequences of violations to
the above rule, the msCAN12 drives the TxCAN pin into recessive state.
In POWER_DOWN mode, no registers can be accessed.
17.8.4 Programmable Wake-Up Function
The msCAN12 can be programmed to apply a low-pass filter function to
the RxCAN input line while in SLEEP mode (see control bit WUPM in the
module control register, msCAN12 Module Control Register 0
(CMCR0)). This feature can be used to protect the msCAN12 from
wake-up due to short glitches on the CAN bus lines. Such glitches can
result from electromagnetic interference within noisy environments.
Technical Data
MC68HC912DG128 — Rev 3.0
MSCAN Controller
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