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Chapter 16
FCAN Controller
User’s Manual U16702EE3V2UD00
<4> Data field
The data field contains the amount of data (byte units) set by the control field. Up to 8 units of data
can be set.
Figure 16-9:
Data Field
Remark:
D: Dominant = 0
R: Recessive = 1
<5> CRC field
The CRC field is a 16-bit field that is used to check for errors in transmit data.
Figure 16-10:
CRC Field
Remark:
D: Dominant = 0
R: Recessive = 1
•
The polynomial P(X) used to generate the 15-bit CRC sequence is expressed as follows.
P(X) = X
15
+ X
14
+ X
10
+ X
8
+ X
7
+ X
4
+ X
3
+ 1
•
Transmitting node: Transmits the CRC sequence calculated from the data (before bit stuffing)
in the start of frame, arbitration field, control field, and data field.
•
Receiving node:
Compares the CRC sequence calculated using data bits that exclude the
stuffing bits in the receive data with the CRC sequence in the CRC field. If
the two CRC sequences do not match, the node issues an error frame.
R
D
Data 0
(8 bits)
MSB
→
LSB
Data 7
(8 bits)
MSB
→
LSB
Data field
(CRC field)
(Control field)
R
D
CRC sequence
CRC delimiter
(1 bit)
(15 bits)
CRC field
(ACK field)
(Data field or control field)
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