Microsemi SmartFusion2 - Transmit Message Control and Command Register

CAN Controller
UG0331 User Guide Revision 15.0 456
12.6.5 Transmit Message Control and Command Register
Each transmit buffer can be configured through a set of registers. Those registers are broken down into a
Control/Command register, Identifier register, Data high register, and Data low register. In the
Command/Control register, some bits are setting a control flag and others are setting a command flag.
The following tables provide a detailed description of transmit message0 buffer registers bits.
Note: The rest of the transmit messages (message1 to message31) follow the same registers definition as
message0.
Table 444 • TX_MSG0_CTRL_CMD
Bit Number Name
Reset
Value Description
[31:24] Reserved 0 Reserved
23 WPN 1 Write protect not
0: Bit[21:16] remain unchanged
1: The write protect is not set and bit[21:16] are modified, by default.
The read back value of this bit is undefined
Using the WPN flag enables simple retransmission of the same
message by only having to set the TxReq and TxAbort flags without
taking care of the special flags
22 Reserved 0 Reserved
21 RTR 0 RTR; control flag bit
0: Standard message
1: RTR message
20 IDE 0 Extended identifier bit; Control flag bit
0: This is a standard format message
1: This is an extended format message
[19:16] DLC 0 Data length code; Control flag bit
Invalid values are transmitted as they are, but the number of data bytes
is limited to eight
0: Message has 0 data bytes
1: Message has 1 data byte
...
8: Message has 8 data bytes
9-15: Message has 8 data bytes
[15:4] Reserved 0 Reserved
3 WPN 1 Write protect not
0: Bit[2] remains unchanged.
1: The write protect is not set and Bit[2] is modified, default.
2 TxIntEbl 0 Tx interrupt enable; Control flag bit
0: Interrupt is disabled.
1: Interrupt enabled, successful message transmission sets the
TX_MSG flag in the interrupt controller.
1 TxAbort 0 Transmit abort request; Command flag bit
0: Idle
1: Requests removal of a pending message.
The message is removed the next time an arbitration loss happens. The
flag is cleared when the message is removed or when the message
wins arbitration. The TxReq flag is cleared at the same time.