
Slave LIN Interface Controller (SLIC) Module
MC68HC908QL4  MC68HC908QL3  MC68HC908QL2 Data Sheet, Rev. 4
138
Freescale Semiconductor
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.