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PRI
The Transmit Priority Code field holds the
software-defined transmit priority code for the
message buffer.
DLC
The Data Length Code field determines the
number of data bytes within a received/trans-
mitted frame. For transmission, these bits
need to be set according to the number of
data bytes to be transmitted. For reception,
these bits indicate the number of valid re-
ceived data bytes available in the message
buffer. Table 53 shows the possible bit combi-
nations for DLC3:0 for data lengths from 0 to
8 bytes.
Table 53 Data Length Coding
DLC
0000
0001
0010
0011
0100
0101
0110
0111
1000
Buffer
Address
Register
0E F0XEh
ID1
0E F0XCh
ID0
0E F0XAh
DATA0
0E F0X8h
DATA1
0E F0X6h
DATA2
0E F0X4h
DATA3
0E F0X2h
TSTP
0E F0X0h
CNSTAT
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Number of Data Bytes
0
1
2
3
4
5
6
7
8
Table 54 Standard Frame with 8 Data Bytes
15
14
13
12
11
Data1[7:0]
Data3[7:0]
Data5[7:0]
Data7[7:0]
DLC
Note: The maximum number of data bytes received/trans-
mitted is 8, even if the DLC field is set to a value greater than
8. Therefore, if the data length code is greater or equal to
eight bytes, the DLC field is ignored.
19.10.2 Storage of Standard Messages
During the processing of standard frames, the Extended-
Identifier (IDE) bit is clear. The ID1[3:0] and ID0[15:0] bits
are "don't care" bits. A standard frame with eight data bytes
is shown in Table 54.
IDE
The Identifier Extension bit determines wheth-
er the message is a standard frame or an ex-
tended frame.
0 – Message is a standard frame using 11
identifier bits.
1 – Message is an extended frame.
RTR
The Remote Transmission Request bit indi-
cates whether the message is a data frame or
a remote frame.
0 – Message is a data frame.
1 – Message is a remote frame.
ID
The ID field is used for the 11 standard frame
identifier bits.
10
9
8
7
ID[10:0]
Don't Care
TSTP[15:0]
Reserved
130
6
5
4
3
2
RTR IDE
Don't Care
Data2[7:0]
Data4[7:0]
Data6[7:0]
Data8[7:0]
PRI
ST
1
0
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