CP3BT26 Datasheet, PDF (131/278 Pages) National Semiconductor (TI) – Reprogrammable Connectivity Processor with Bluetooth-R, USB, and CAN Interfaces

19.10.3 Storage of Messages with Less Than 8 Data
Bytes
The data bytes that are not used for data transfer are “don’t
cares”. If the object is transmitted, the data within these
bytes will be ignored. If the object is received, the data with-
in these bytes will be overwritten with invalid data.
19.10.4 Storage of Extended Messages
If the IDE bit is set, the buffer handles extended frames. The
storage of the extended ID follows the descriptions in
Table 55. The SRR bit is at the bit position of the RTR bit for
standard frame and needs to be transmitted as 1.
Address
Buffer
Register
15
0E F0XEh ID1
0E F0XCh
0E F0XAh
0E F0X8h
ID0
DATA0
DATA1
0E F0X6h
0E F0X4h
0E F0X2h
DATA2
DATA3
TSTP
0E F0X0h CNSTAT
Table 55 Extended Messages with 8 Data Bytes
14 13 12 11 10 9 8 7 6 5 4 3
ID[28:18]
SRR IDE
ID[14:0]
Data1[7:0]
Data2[7:0]
Data3[7:0]
Data4[7:0]
Data5[7:0]
Data6[7:0]
Data7[7:0]
Data8[7:0]
TSTP[15:0]
DLC
Reserved
PRI
210
ID17:15]
RTR
ST
SRR
IDE
RTR
ID
The Substitute Remote Request bit replaces
the RTR bit used in standard frames at this bit
position. The SRR bit needs to be set by soft-
ware if the buffer is configured to transmit a
message with an extended identifier. It will be
received as monitored on the CAN bus.
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.
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.
The ID field is used to build the 29-bit identifier
of an extended frame.
131
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