NEC V850E/Dx3 Preliminary User's Manual page 648

Chapter 19
648
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<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.
(Control field)
R
D
Data 0
(8 bits)
Figure 19-9 Data field
Note 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.
(Data field or control field)
R
D
Figure 19-10 CRC field
Note D: Dominant = 0
R: Recessive = 1
• The polynomial P(X) used to generate the 15-bit CRC sequence is
expressed as follows.
15
P(X) = X
• Transmitting node:
• Receiving node:
Preliminary User's Manual U17566EE1V2UM00
Data field
→
MSB LSB
CRC field
CRC sequence
(15 bits)
14 10 8 7 4
+ X + X + X + X + X
Transmits the CRC sequence calculated from the
data (before bit stuffing) in the start of frame,
arbitration field, control field, and data field.
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.
CAN Controller (CAN)
(CRC field)
Data 7
(8 bits)
→
MSB LSB
(ACK field)
CRC delimiter
(1 bit)
3
+ X + 1