Message RAM
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SPNU563A – March 2018
Copyright © 2018, Texas Instruments Incorporated
Controller Area Network (DCAN) Module
Table 27-2. Message Object Field Descriptions (continued)
Name
Value
Description
EOB
End of Block
0
The message object is part of a FIFO Buffer block and is not the last message object of this FIFO
Buffer block.
1
The message object is a single message object or the last message object in a FIFO Buffer block.
Note: This bit is used to concatenate multiple message objects to build a FIFO Buffer. For single
message objects (not belonging to a FIFO Buffer), this bit must always be set to 1.
NewDat
New Data
0
No new data has been written into the data bytes of this message object by the Message Handler
since the last time when this flag was cleared by the CPU.
1
The Message Handler or the CPU has written new data into the data bytes of this message object.
MsgLst
Message Lost (only valid for message objects with direction = receive)
0
No message was lost since the last time when this bit was reset by the CPU.
1
The Message Handler stored a new message into this message object when NewDat was still set, so
the previous message has been overwritten.
RxIE
Receive Interrupt Enable
0
IntPnd will not be triggered after the successful reception of a frame.
1
IntPnd will be triggered after the successful reception of a frame.
TxIE
Transmit Interrupt Enable
0
IntPnd will not be triggered after the successful transmission of a frame.
1
IntPnd will be triggered after the successful transmission of a frame.
IntPnd
Interrupt Pending
0
This message object is not the source of an interrupt.
1
This message object is the source of an interrupt. The Interrupt Identifier in the Interrupt Register will
point to this message object if there is no other interrupt source with higher priority.
RmtEn
Remote Enable
0
At the reception of a Remote Frame, TxRqst is not changed.
1
At the reception of a Remote Frame, TxRqst is set.
TxRqst
Transmit Request
0
This message object is not waiting for a transmission.
1
The transmission of this message object is requested and is not yet done.
DLC[3:0]
Data Length Code
0-8
Data Frame has 0-8 data bytes.
9-15
Data Frame has 8 data bytes.
Note: The Data Length Code of a message object must be defined to the same value as in the
corresponding objects with the same identifier at other nodes. When the Message Handler stores a
data frame, it will write the DLC to the value given by the received message.
Data 0
1st data byte of a CAN Data Frame
Data 1
2nd data byte of a CAN Data Frame
Data 2
3rd data byte of a CAN Data Frame
Data 3
4th data byte of a CAN Data Frame
Data 4
5th data byte of a CAN Data Frame
Data 5
6th data byte of a CAN Data Frame
Data 6
7th data byte of a CAN Data Frame
Data 7
8th data byte of a CAN Data Frame
Note:
Byte Data 0 is the first data byte shifted into the shift register of the CAN Core during a
reception, byte Data 7 is the last. When the Message Handler stores a data frame, it will write all the
eight data bytes into a message object. If the Data Length Code is less than 8, the remaining bytes of
the message object may be overwritten by undefined values.