MC68HC908QL4 Datasheet, PDF (156/226 Pages) Motorola, Inc – Microcontrollers

Slave LIN Interface Controller (SLIC) Module
PROCESS
VALID ID
N
COMMAND MESSAGE
?
Y
EXTENDED FRAME ^Y
?
N
WRITE SLCDLC FOR THIS ID
0n00 0xxx
(TXGO = 0)
(CHKMOD = n)
EXIT ISR
PROCESS ERROR CODE:
BYTE FRAMING ERROR
CHECKSUM-ERROR
NO-BUS-ACTIVITY
RECEIVE BUFFER OVERRUN
EXIT ISR
RETURN TO IDLE
INTERRUPT
READ SLCSV
CLEAR SLCF
Y
ERROR CODE
?
N
EMPTY RX BUFFER
PROCESS
REQUEST MESSAGE
INITIALIZE SW BYTE COUNT
WRITE SLCDLC FOR THIS ID
0nxx xxxx
(TXGO = 0)
(CHKMOD = n)
EXIT ISR
INTERRUPT
READ SLCSV
CLEAR SLCF
ERROR CODE
Y
?
PROCESS ERROR CODE:
BYTE FRAMING ERROR
NO-BUS-ACTIVITY
RECEIVE BUFFER OVERRUN
N
1. EMPTY RX BUFFER
2. DECREMENT SW BYTE COUNT BY 8
EXIT ISR
RETURN TO IDLE
N
LAST FRAME
(SW BYTE COUNT £8)
?
Y
Figure 14-16. Handling Command Messages (Data Receive)
The SLIC transmit go (TXGO) bit should be 0 for command frames, indicating to the SLIC that data is
coming from the master. The checksum mode control (CHKMOD) bit allows the user to select which
method of checksum calculation is desired for this message frame. The LIN 1.3 checksum does not
include the identifier byte in the calculation, while the SAE version does include this byte. Because the
identifier is already received by the SLIC by this time, the default is to include it in the calculation. If a LIN
1.3 checksum is desired, a 1 in CHKMOD will reset the checksum circuitry to begin calculating the
MC68HC908QL4 Data Sheet, Rev. 7
156
Freescale Semiconductor