MC9S08EL32 Datasheet, PDF (213/356 Pages) Freescale Semiconductor, Inc – 8-Bit HCS08 Central Processor Unit (CPU)

This means an extra step is taken inside the interrupt service routine after the identifier has been decoded
and is determined to be an ID for a request message frame.
Figure 12-16 deals with request messages, where the SLIC will be transmitting data to the master node. If
the received identifier corresponds to a standard LIN command frame (i.e., 1-8 data bytes), the message
processing is very simple. The user must load the data to be transmitted into the transmit buffer by writing
it to the SLCD registers. The first byte to be transmitted on the LIN bus must be loaded into SLCD0, then
SLCD1 for the second byte, etc. After all of the bytes to be transmitted are loaded in this way, a single
write to SLCDLC will allow the user to encode the number of data bytes to be transmitted (1–8 bytes for
standard request frames), set the proper checksum calculation method for the data (CHKMOD), as well as
signal the SLIC that the buffer is ready by writing a 1 to TXGO. TXGO will remain set to 1 until the buffer
is sent successfully or an error is encountered, signaling to the application code that the buffer is in process
of transmitting. In cases of 1–8 data bytes only being sent (standard LIN request frames), the SLIC
automatically calculates and transmits the checksum byte at the end of the message frame. The user can
exit the ISR after SLCDLC has been written and the SLCF flag has been cleared.
MC9S08EL32 Series and MC9S08SL16 Series Data Sheet, Rev. 3
Freescale Semiconductor
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