NXP Semiconductors MPC5644A, Reference Manual, Page: 1378 / 1735

Enhanced Serial Communication Interface (ESCI)
MPC5644A Microcontroller Reference Manual, Rev. 6
1378 Freescale Semiconductor
31.4.6.2 LIN frame formats
The term LIN frame refers to a sequence of LIN byte fields preceded by a break character, both are
described in
Section 31.4.2, Frame formats ”.
The eSCI module allows to generate LIN frames for LIN
slaves of LIN standards 1.3 and 2.0.
31.4.6.2.1 LIN byte field reception
The reception of a LIN byte field starts with the successful start bit qualification and is finished with the
reception of the 16-th sample of the stop bit when no start bit start bit qualification pattern has been
detected. If a start bit start bit qualification pattern has been detected at or after the 10-th sample of the stop
bit, the reception ends at this sample. An ongoing reception is indicated by the RACT status bit in
Interrupt
Flag and Status Register 1 (eSCI_IFSR1) .
The RACT flag is set if all of the following conditions are fulfilled,
1. the receiver is enabled (eSCI_CR1[RE] = 1), and
2. the LIN task is not in reset (eSCI_LCR1[LRES] = 0), and
3. the start bit start bit qualification pattern has been received (see Section 31.4.5.3.15, Start Bit
Sampling ”).
The RACT flag is cleared if at least one of the following conditions is fulfilled,
1. the receiver is disabled (eSCI_CR1[RE] = 0), or
2. the LIN task is in reset (eSCI_LCR1[LRES] = 1), or
3. the start bit verification fails at sample 7 according to Table 31-32 , or
4. the 16-th sample of the stop bit has been received and no start bit qualification pattern has been
detected at or after the 10-th sample.
31.4.6.2.2 Standard LIN frames
A standard LIN frame, shown in Figure 31-36 consists of a break character, a sync field, an ID field, zero
or more data fields, and a checksum field. The data fields and the checksum field are generated by the LIN
master for TX LIN frames and generated by the LIN slave for RX LIN frames. The header fields will
always be generated by the LIN master.
Figure 31-36. Standard LIN frame format
31.4.6.2.3 CRC Enhanced LIN frames
The CRC Enhanced LIN frames shown in Figure 31-37 contain two additional CRC byte fields. These
fields are located between the last data field and the Checksum field. The value of the CRC is calculated
on the same byte fields as the Checksum is calculated on. The polynom used for the CRC calculation is
defined by
LIN CRC polynomial register (eSCI_LPR) . The eSCI module generates the CRC fields for TX
frames and checks the CRC fields for RX frames if the CRC bit in the LIN transmit register (eSCI_LTR)
was written with a value of 1.
Break Synch Identifier Data 1 Data 2 Data N Checksum