Datasheet

V850ES/JG3-H, V850ES/JH3-H CHAPTER 20 CAN CONTROLLER
R01UH0042EJ0500 Rev.5.00 Page 895 of 1513
Aug 12, 2011
20.2 CAN Protocol
CAN (Controller Area Network) is a high-speed multiplex communication protocol for real-time communication in
automotive applications (class C). CAN is prescribed by ISO 11898. For details, refer to the ISO 11898 specifications.
The CAN specification is generally divided into two layers: a physical layer and a data link layer. In turn, the data link
layer includes logical link and medium access control. The composition of these layers is illustrated below.
Figure 20-2. Composition of Layers
Physical layer Prescription of signal level and bit description
Data link
layer
Note
· Logical link control (LLC)
· Medium access control (MAC)
· Acceptance filtering
· Overload report
· Recovery management
· Data capsuled/not capsuled
· Frame coding (stuffing/no stuffing)
· Medium access management
· Error detection
· Error report
· Acknowledgment
· Seriated/not seriated
Higher
Lower
Note CAN controller specification
20.2.1 Frame format
(1) Standard format frame
• The standard format frame uses 11-bit identifiers, which means that it can handle up to 2,048 messages.
(2) Extended format frame
• The extended format frame uses 29-bit (11 bits + 18 bits) identifiers, which increases the number of messages
that can be handled to 2,048 × 2
18
messages.
• An extended format frame is set when “recessive level” (CMOS level of “1”) is set for both the SRR and IDE bits
in the arbitration field.