CP3BT23 Datasheet, PDF (96/260 Pages) Texas Instruments – CP3BT23 Reprogrammable Connectivity Processor with Bluetooth and Dual CAN Interfaces

Data Length Code (DLC)
The remainder of this division is the CRC sequence trans-
The DLC field indicates the number of bytes in the data field.
It consists of four bits. The data field can be of length zero.
The admissible number of data bytes for a data frame rang-
es from 0 to 8.
mitted over the bus. On the receiver side, the module di-
vides all bit fields up to the CRC delimiter excluding stuff
bits, and checks if the result is zero. This will then be inter-
preted as a valid CRC. After the CRC sequence a single “re-
cessive” bit is transmitted as the CRC delimiter.
Data Field
The Data field consists of the data to be transferred within a
data frame. It can contain 0 to 8 bytes. A remote frame has
no data field.
ACK Field
The ACK field is two bits long and contains the ACK slot and
the ACK delimiter. The ACK slot is filled with a “recessive”
bit by the transmitter. This bit is overwritten with a “domi-
Cyclic Redundancy Check (CRC)
nant” bit by every receiver that has received a correct CRC
The CRC field consists of the CRC sequence followed by ^{sequence. The second bit of the ACK field is a “recessive”}
the CRC delimiter. The CRC sequence is derived by the ^{bit called the acknowledge delimiter.}
transmitter from the modulo 2 division of the preceding bit The End of Frame field closes a data and a remote frame. It
fields, starting with the SOF up to the end of the data field, consists of seven “recessive” bits.
excluding stuff-bits, by the generator polynomial:
18.2.3 CAN Frame Formats
x¹⁵ + x¹⁴ + x¹⁰ + x⁸ + x⁷ + x⁴ + x³ + 1
Data Frame
The structure of a standard data frame is shown in
Figure 34. The structure of an extended data frame is
shown in Figure 35.
te _{Arbitration Field}
le ¹¹
Control Field
4
STANDARD DATA FRAME (number of bits = 44 + 8N)
8N (0 < N < 8)
Data Field
8
8
16
CRC Field
15
CRC
END OF
FRAME
d
IDENTIFIER
10 ... 0
o _Note:
d = dominant
s ^{r = recessive}
ddd
DATA
LENGTH CODE
Bit Stuffing
Figure 34. Standard Data Frame
r rrrrrrrr
DS020
b_{EXTENDED DATA FRAME (number of bits = 64 + 8N)}
Arbitration Field
Control Field
8N (0 < N < 0)
Data Field
O¹¹
18
4
8
8
16
CRC Field
15
END OF
FRAME
CRC
d
rr
ddd
IDENTIFIER
28 ... 18
IDENTIFIER
17 ... 0
DATA
LENGTH CODE
r rrrrrrrr
Note:
d = dominant
r = recessive
Bit Stuffing
Figure 35. Extended Data Frame
95
DS021
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