MC68HC908QL4 Datasheet, PDF (148/226 Pages) Motorola, Inc – Microcontrollers

Slave LIN Interface Controller (SLIC) Module
14.8.7 SLIC Data Length Code Register
The SLIC data length code register (SLCDLC) is the primary functional control register for the SLIC
module during normal LIN operations. It contains the data length code of the message buffer, indicating
how many bytes of data are to be sent or received, as well as the checksum mode control and transmit
enabling bit.
Read:
Write:
Reset:
Bit 7
TXGO
0
6
CHKMOD
0
5
DLC5
0
4
DLC4
0
3
DLC3
0
2
DLC2
0
1
DLC1
0
Bit 0
DLC0
0
Figure 14-11. SLIC Data Length Code Register (SLCDLC)
TXGO — SLIC Transmit Go
This bit controls whether the SLIC module is sending or receiving data bytes. This bit is automatically
reset to 0 after a transmit operation is complete or an error is encountered and transmission has been
aborted.
1 = Initiate SLIC transmit
The SLIC assumes the user has loaded the proper data into the message buffer and will begin
transmitting the number of bytes indicated in the SLCDLC bits. If the number of bytes is greater
than 8, the first 8 bytes will be transmitted and an interrupt will be triggered (if unmasked) for
the user to enter the next bytes of the message. If the number of bytes is 8 or fewer, the SLIC
will transmit the appropriate number of bytes and automatically append the checksum to the
transmission.
0 = SLIC receive data
CHKMOD — LIN Checksum Mode
CHKMOD is used to decide what checksum method to use for this message frame. Resets after error
code or message frame complete. CHKMOD must be written (if desired) only after the reception of an
identifier and before the reception or transmission of data bytes. Writing this bit to a one clears the
current checksum calculation. The one exception is when a byte framing error is detected and the
checksum calculation should be reset. (See Byte Framing Error description in section 14.8.6.1 LIN
Mode Operation.)
1 = Checksum calculated without the identifier byte (LIN spec <= 1.3)
0 = Checksum calculated with the identifier byte included
(SAE J2602/LIN 2.0)
DLC — Data Length Control Bits
The value of the bits indicate the number of data bytes in message. Values $00–$07 are for “normal”
LIN messaging. Values $08–$3F are for “extended” LIN messaging.
Table 14-4. Data Length Control
DLC[5:0]
$00
$01
$02
...
$3D
$3E
$3F
Message Data Length (Number of Bytes)
1
2
3
...
62
63
64
MC68HC908QL4 Data Sheet, Rev. 7
148
Freescale Semiconductor