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CP3BT26
Figure 61. Data Direction Bit Clear
Setting the DDIR bit will cause the direction of the data stor-
age to be reversed — the last byte received is stored at the
highest address and the first byte is stored at the lowest ad-
dress, as shown in Figure 62.
Figure 62. Data Direction Bit Set
LO The Listen Only bit can be used to configure
the CAN interface to behave only as a receiv-
er. This means:
• Cannot transmit any message.
• Cannot send a dominant ACK bit.
• When errors are detected on the bus, the
CAN module will behave as in the error
passive mode.
Using this listen only function, the CAN inter-
face can be adjusted for connecting to an op-
erating network with unknown bus speed.
0 – Transmit/receive mode.
1 – Listen-only mode.
IGNACK When the Ignore Acknowledge bit is set, the
CAN module does not expect to receive a
dominant ACK bit to indicate the validity of a
transmitted message. It will not send an error
frame when the transmitted frame is not ac-
knowledged by any other CAN node. This fea-
ture can be used in conjunction with the
LOOPBACK bit for stand-alone tests outside
of a CAN network.
0 – Normal mode.
1 – The CAN module does not expect to re-
ceive a dominant ACK bit to indicate the
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.
Storage of Data Bytes
in the Buffer Memory
Sequence of Data Bytes on the Bus
CRCData8
t
Data7Data6Data5Data4Data3Data2Data1ID
Data2Data10A
16
Data4Data308
16
Data6Data506
16
Data8Data704
16
Data BytesADDR Offset
DS045
Storage of Data Bytes
in the Buffer Memory
Sequence of Data Bytes on the Bus
CRCData8
t
Data7Data6Data5Data4Data3Data2Data1ID
Data7Data80A
16
Data5Data608
16
Data3Data406
16
Data1Data204
16
Data BytesADDR Offset
DS046