MC68HC908QL4 Datasheet, PDF (146/226 Pages) Motorola, Inc – Microcontrollers

Slave LIN Interface Controller (SLIC) Module
specification. Bit errors are not checked when the LIN bus is running at high speed due to the
effects of physical layer round trip delay. Bit errors are fully checked at all LIN 2.0 compliant speeds
of 20 kbps and below.
• Receiver Buffer Overrun Error
This error is an indication that the receive buffer has not been emptied and additional bytes have
been received, resulting in lost data. Because this interrupt is higher priority than the receive buffer
full interrupts, it will appear first when an overflow condition occurs. There will, however, be a
pending receive interrupt which must also be cleared after the buffer overrun flag is cleared.
• Checksum Error (LIN specified error)
The checksum error occurs when the calculated checksum value does not match the expected
value. If this error is encountered, it is important to verify that the correct checksum calculation
method was employed for this message frame. Refer to the LIN specification for more details on
the calculations.
• Byte Framing Error
This error comes from the standard UART definition for byte encoding and occurs when the STOP
bit is sampled and reads back as a 0. STOP should always read as 1. In LIN mode (BTM=0), if a
byte framing error occurs in an identifier byte of a LIN header the user must set and then clear
CHKMOD to ensure that the checksum calculation is reset. Failure to do so can result in an
improperly calculated enhanced checksum for the subsequent LIN frame. Because any byte
framing error indicates a corrupted byte, the best practice is to always toggle CHKMOD in the case
of a byte framing error.
NOTE
A byte framing error can also be an indication that the number of data bytes
received in a LIN message frame does not match the value written to the
SLCDLC register. See 14.9.7 Handling LIN Message Headers for more
details.
• Identifier Received Successfully
This interrupt source indicates that a LIN identifier byte has been received with correct parity and
is waiting in the LIN identifier buffer (SLCID). Upon reading this interrupt source from SLCSV, the
user can then decode the identifier in software to determine the nature of the LIN message frame.
To clear this source, SLCID must be read.
• Identifier-Parity-Error
A parity error in the identifier (i.e., corrupted identifier) will be flagged. Typical LIN slave
applications do not distinguish between an unknown but valid identifier, and a corrupted identifier.
However, it is mandatory for all slave nodes to evaluate in case of a known identifier all eight bits
of the ID-Field and distinguish between a known and a corrupted identifier. The received identifier
value is reported in SLCID so that the user software can choose to acknowledge or ignore the
parity error message.
• Inconsistent-Synch-Field-Error
An Inconsistent-Synch-Field-Error must be detected if a slave detects the edges of the SYNCH
FIELD outside the given tolerance.
• Wakeup
The wakeup interrupt source indicates that the SLIC module has entered SLIC run mode from SLIC
stop mode.
MC68HC908QL4 Data Sheet, Rev. 7
146
Freescale Semiconductor