EP80579 Datasheet, PDF (1576/1916 Pages) Intel Corporation – Intel® EP80579 Integrated Processor Product Line

Intel^® EP80579 Integrated Processor
Figure 39-5. Extended CAN Remote Frame
Extended Remote Frame
Recessive level
Bus Idle _{1 11 1 1}
Dominant level
Start of Frame
Identifier
Arbitration Field
(without IDE bit)
SRR Bit (R)
IDE Bit (R)
Extended
Identifier
RTR Bit (R)
Control Field
(plus IDE bit)
(2 reserved (D))
DLC
18 1 2 4
15 1 1 1 7
3 ^{Bus Idle}
CRC Field
CRC Sequence
CRC Delimiter
Acknowledge Field
ACK Slot
ACK Delimiter
End of Frame
Intermission
39.4.3.3
Error Frames
CAN, as a message-oriented protocol, uses error signaling. Each network node checks
each message that is transmitted on the bus for errors. When a transmitting or
receiving network node detects an error, the node signals all other nodes by
transmitting an error message (Error Frame). The Error Frame contains a six bit
combination with the same polarity, normally as a dominant bit sequence (active error
flag). All network nodes detect the error signal and cancel the segments of a message
already received. Consistent data is thus ensured for all nodes of the network.
An Error Frame consists of two fields:
• Error Flag field:
— An active Error Flag consists of six consecutive dominant bits. This violates the
CAN protocol bit stuffing rule, and in turn all nodes on the network will
generate error frames. The error frame field will then vary from a minimum of 6
to maximum of 12 consecutive dominant bits.
— A passive Error Flag consists of six consecutive recessive bits, unless
overwritten by dominant bits from other nodes. Unless the bus master
transmits the passive Error Flag, the passive error flag will not affect any other
node on the network.
• Error Delimiter field: consists of eight recessive bits and terminates the Error
Frame.
Intel^® EP80579 Integrated Processor Product Line Datasheet
1576
August 2009
Order Number: 320066-003US