MC68HC908QL4 Datasheet, PDF (138/226 Pages) Motorola, Inc – Microcontrollers

Slave LIN Interface Controller (SLIC) Module
instruction the CPU executes to cause the SLIC module to enter SLIC stop, the message which wakes
up the SLIC module (and the CPU) may or may not be received.
There are two different possibilities:
1. Wakeup from SLIC Stop with CPU in STOP
When the CPU executes the STOP instruction, all clocks in the MCU, including clocks to the SLIC
module, are turned off. Therefore, the message which wakes up the SLIC module and the CPU
from stop mode will not be received. This is due primarily to the amount of time required for the
MCU's oscillator to stabilize before the clocks can be applied internally to the other MCU modules,
including the SLIC module.
2. Wakeup from SLIC Stop with CPU in WAIT
If the CPU executes the WAIT instruction and the SLIC module enters the stop mode
(SLCWCM = 1), the clocks to the SLIC module are turned off, but the clocks in the MCU continue
to run. Therefore, the message which wakes up the SLIC module from stop and the CPU from wait
mode will be received correctly by the SLIC module. This is because very little time is required for
the CPU to turn the clocks to the SLIC module back on after the wakeup interrupt occurs.
NOTE
While the SLIC module will correctly receive a message which arrives when
the SLIC module is in stop or wait mode and the MCU is in wait mode, if the
user enters this mode while a message is being received, the data in the
message will become corrupted. This is due to the steps required for the
SLIC module to resume operation upon exiting stop or wait mode, and its
subsequent resynchronization with the LIN bus.
14.5.8 Normal and Emulation Mode Operation
The SLIC module operates in the same manner in all normal and emulation modes. All SLIC module
registers can be read and written except those that are reserved, unimplemented, or write once. The user
must be careful not to unintentionally write a register when using 16-bit writes to avoid unexpected SLIC
module behavior.
14.5.9 Special Mode Operation
Some aspects of SLIC module operation can be modified in special test mode. This mode is reserved for
internal use only.
14.5.10 Low-Power Options
The SLIC module can save power in disabled, wait, and stop modes. A complete description of what the
SLIC module does while in a low-power mode can be found in 14.5 Modes of Operation.
14.6 SLIC During Break Interrupts
The BCFE bit in the BSCR register has no affect on the SLIC module. Therefore the SLIC modules status
bits cannot be protected during break.
MC68HC908QL4 Data Sheet, Rev. 7
138
Freescale Semiconductor