Datasheet

MC9S08EL32 Series and MC9S08SL16 Series Data Sheet, Rev. 3
212 Freescale Semiconductor
Figure 12-15. 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 checksum
COMMAND MESSAGE
?
PROCESS
VALID ID
N
Y
INITIALIZE SW BYTE COUNT
PROCESS
REQUEST MESSAGE
EXTENDED FRAME
?
Y
N
WRITE SLCDLC FOR THIS ID
0nxx xxxx
(TXGO = 0)
(CHKMOD = n)
EXIT ISR
ERROR CODE
?
Y
N
PROCESS ERROR CODE:
EXIT ISR
RETURN TO IDLE
1. EMPTY RX BUFFER
2. DECREMENT SW BYTE COUNT BY 8
LAST FRAME
?
Y
N
(SW BYTE COUNT <8)
WRITE SLCDLC FOR THIS ID
0n00 0xxx
(TXGO = 0)
(CHKMOD = n)
EXIT ISR
ERROR CODE
?
Y
N
PROCESS ERROR CODE:
EXIT ISR
RETURN TO IDLE
EMPTY RX BUFFER
BYTE FRAMING ERROR
CHECKSUM-ERROR
NO-BUS-ACTIVITY
BYTE FRAMING ERROR
NO-BUS-ACTIVITY
INTERRUPT
READ SLCSV
INTERRUPT
READ SLCSV
RECEIVE BUFFER OVERRUN
RECEIVE BUFFER OVERRUN
CLEAR SLCF
3. CLEAR SLCF
CLEAR SLCF
CLEAR SLCF