CHAPTER 19 FCAN CONTROLLER (V850/SC3)
User’s Manual U15109EJ3V0UD
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<4> Data field
The data field contains the amount of data (byte unit) set by the control field. Up to 8 units of data can
be set.
Figure 19-17. Data Field
R
D
Data
(8 bits)
Data
(8 bits)
Data field
(CRC field)
(Control 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 19-18. CRC Field
R
D
CRC sequence
CRC delimiter
(1 bit)
(15 bits)
CRC field
(ACK field)
(Data field or control 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: The CRC sequence calculated from the data (before bit stuffing) in the start of
frame, arbitration field, control field, or data field is the transferred.
•
Receiving node:
The CRC sequence calculated using data bits that exclude the stuffing bits in the
receive data is compared with the CRC sequence in the CRC field. If the two
CRC sequences do not match, the node is transferred to an error frame.