Message RAM
1578
SPRUHE8E – October 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
M3 Controller Area Network (CAN)
Table 23-2. Message Object Field Descriptions (continued)
Name
Value
Description
MXtd
Mask Extended Identifier
0
The extended identifier bit (IDE) has no effect on the acceptance filtering.
1
The extended identifier bit (IDE) is used for acceptance filtering.
Note: When 11-bit ("standard") Identifiers are used for a message object, the identifiers of received data
frames are written into bits ID[28:18]. For acceptance filtering, only these bits together with mask bits
Msk[28:18] are considered.
Dir
Message Direction
0
Direction = receive: On TxRqst, a remote frame with the identifier of this message object is transmitted. On
reception of a data frame with matching identifier, the message is stored in this message object.
1
Direction = transmit: On TxRqst, a data frame is transmitted. On reception of a remote frame with matching
identifier, the TxRqst bit of this message object is set (if RmtEn = one).
MDir
Mask Message Direction
0
The message direction bit (Dir) has no effect on the acceptance filtering.
1
The message direction bit (Dir) is used for acceptance filtering.
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 one.
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. This message object is the source of an interrupt.
1
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.
Note: See
for details on the setup of RmtEn and UMask for remote frames.
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.
8-15
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.
