NXP Semiconductors MPC5566 - Page 1012

Enhanced Serial Communication Interface (eSCI)
MPC5566 Microcontroller Reference Manual, Rev. 2
Freescale Semiconductor 21-15
Table 21-8. ESCIx_LTR First Byte Field Description
Field Description
0–1
Pn
Parity bit n. When parity generation is enabled (ESCIx_LCR[PRTY] = 1), the parity bits are generated automatically.
Otherwise they must be provided in this field.
2–7
IDn
1
1
The values 3C, 3D, 3E and 3F of the ID-field (ID0-5) indicate command and extended frames. Refer to LIN Specification
Package Revision 2.0.
Header bit n. The LIN address, for LIN 1.x standard frames the length bits must be set appropriately so the extended
frames are recognized by their specific patterns. Refer to the Table 2 1-9 .
8–31 Reserved.
Table 21-9. ESCIx_LTR Second-Byte Field Description
Field Description
0–7
Ln
Length bit n. Defines the length of the frame (0 to 255 data bytes). This information is needed by the LIN state
machine to insert the checksum or CRC pattern as required. LIN 1.x slaves only accepts frames with 2, 4, or 8 data
bytes.
8–31 Reserved.
Table 21-10. ESCIx_LTR Third-Byte Field Descriptions
Field Description
0
HDCHK
Header checksum enable. Include the header fields into the mod 256 checksum of the standard frames.
1
CSUM
Checksum enable. Append a checksum byte to the end of a TX frame. Verify the checksum byte of an RX frame.
2
CRC
CRC enable. Append two CRC bytes to the end of a TX frame. Verify the two CRC bytes of an RX frame are correct.
If both CSUM and CRC bits are set, the LIN FSM first appends the CRC bytes, then the checksum byte, and are
processed in this order. If HDCHK is set, the CRC calculation includes the header and data bytes, otherwise, the
CRC is performed on the data bytes only. CRC bytes are not part of the LIN standard; they are normal data bytes
and belong to a higher-level protocol.
3
TX
Transmit direction. Indicates that the eSCI transmits a frame to a slave. Otherwise, an RX frame is assumed, and the
eSCI only transmits the header. The data bytes are received from the slave.
0RX frame
1TX frame
I
D
5
I
D
4
d
a
t
a
b
y
t
e
s
0
0
2
0
1
2
1
0
4
1
1
8