CP3BT23 Datasheet, PDF (118/260 Pages) Texas Instruments – CP3BT23 Reprogrammable Connectivity Processor with Bluetooth and Dual CAN Interfaces

Sequence of Data Bytes on the Bus
ID
Data1
Data2
Data3
Data4
Data5
Data6
Data7
Data8
CRC
t
Storage of Data Bytes
in the Buffer Memory
ADDR Offset
0A₁₆
Data Bytes
Data1
Data2
08₁₆
Data3
Data4
06₁₆
Data5
Data6
04₁₆
Data7
Data8
DS045
Figure 59. Data Direction Bit Clear
Setting the DDIR bit will cause the direction of the data stor- highest address and the first byte is stored at the lowest ad-
age to be reversed — the last byte received is stored at the dress, as shown in Figure 60.
te ^{Sequence of Data Bytes on the Bus}
ID
Data1
Data2
Data3
Data4
Data5
Data6
Data7
Data8
CRC
Storage of Data Bytes
ole ^{in the Buffer Memory}
ADDR Offset
0A₁₆
08₁₆
06₁₆
04₁₆
Data Bytes
Data8
Data7
Data6
Data5
Data4
Data3
Data2
Data1
t
DS046
Figure 60. Data Direction Bit Set
s _LO
The Listen Only bit can be used to configure IGNACK When the Ignore Acknowledge bit is set, the
the CAN interface to behave only as a receiv-
CAN module does not expect to receive a
er. This means:
dominant ACK bit to indicate the validity of a
• Cannot transmit any message.
transmitted message. It will not send an error
b ^{• Cannot send a dominant ACK bit.}
frame when the transmitted frame is not ac-
• When errors are detected on the bus, the
knowledged by any other CAN node. This fea-
CAN module will behave as in the error
ture can be used in conjunction with the
passive mode.
LOOPBACK bit for stand-alone tests outside
Using this listen only function, the CAN inter-
of a CAN network.
O^{face can be adjusted for connecting to an op-}
0 – Normal mode.
erating network with unknown bus speed.
1 – The CAN module does not expect to re-
0 – Transmit/receive mode.
ceive a dominant ACK bit to indicate the
1 – Listen-only mode.
validity of a transmitted message.
LOOPBACK When the Loopback bit is set, all messages
sent by the CAN module can also be received
by a CAN module buffer with a matching buff-
er ID. However, the CAN module does not ac-
knowledge a message sent by itself.
Therefore, the CAN module will send an error
frame when no other device connected to the
bus has acknowledged the message.
0 – No loopback.
1 – Loopback enabled.
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