70353C Datasheet, PDF (6/76 Pages) Microchip Technology – Section 21. Enhanced Controller Area Network

dsPIC33E/PIC24E Family Reference Manual
21.2.3 Remote Frame
A node expecting to receive data from another node can initiate transmission of the respective
data by the source node, by sending a remote frame. A remote frame can be in the standard
format (Figure 21-6) or the extended format (Figure 21-7).
A Remote frame is similar to a data frame, with the following exceptions:
• The RTR bit is recessive (RTR = 1)
• There is no Data field
• The value of the DLC bits is 0 ≤ DLC ≤ 8
Figure 21-6: Format of the Standard Remote Frame
Arbitration Field
S
IDENTIFIER
O
11 Bits
F
Control Field
RI
T D ^RB0
RE
DLC
4 Bits
CRC Field
CRC
16 Bits
ACK Field End-of-Frame (EOF)
ACK
2 Bits
EOF
7 Bits
IFS
3 Bits
SID10
SID1 SID0
11-bit Identifier
IDE is Dominant (Logical ‘0’)
RTR is Recessive (Logical ‘1’)
RB0 is Dominant (Logical ‘0’)
Figure 21-7: Format of the Extended Remote Frame
Arbitration Field
S
IDENTIFIER
SI
IDENTIFIER
O
11 Bits
RD
18 Bits
F
RE
Control Field
CRC Field ACK Field End-of-Frame (EOF)
RRR
TBB
R10
DLC
4 Bits
CRC
16 Bits
ACK
2 Bits
EOF
7 Bits
IFS
3 Bits
SID10
SID0 SID1 EID17
29-bit Identifier
EID1 EID0
IDE is Recessive (Logical ‘1’)
SRR is Recessive (Logical ‘1’)
RTR is Recessive (Logical ‘1’)
RB0 is Dominant (Logical ‘0’)
RB1 is Dominant (Logical ‘0’)
DS70353C-page 21-6
© 2008-2011 Microchip Technology Inc.