DCAN Control Registers
1479
SPNU563A – March 2018
Copyright © 2018, Texas Instruments Incorporated
Controller Area Network (DCAN) Module
Table 27-25. IF1/IF2 Command Register Field Descriptions
Bit
Field
Value
Description
31-24
Reserved
0
These bits are always read as 0. Writes have no effect.
23
WR/RD
Write/Read
0
Direction = Read: Transfer direction is from the message object addressed by Message
Number (Bits [7:0]) to the IF1/IF2 register set.
1
Direction = Write: Transfer direction is from the IF1/IF2 register set to the message object
addressed by Message Number (Bits [7:0]).
22
Mask
Access Mask bits.
0
Mask bits will not be changed.
1
Direction = Read: The Mask bits (Identifier Mask + MDir + MXtd) will be transferred from the
message object addressed by Message Number (Bits [7:0]) to the IF1/IF2 Register set.
Direction = Write: The Mask bits (Identifier Mask + MDir + MXtd) will be transferred from the
IF1/IF2 Register set to the message object addressed by Message Number (Bits [7:0]).
21
Arb
Access Arbitration bits.
0
Arbitration bits will not be changed.
1
Direction = Read: The Arbitration bits (Iden Dir + Xtd + MsgVal) will be transferred from
the message object addressed by Message Number (Bits [7:0]) to the corresponding IF1/IF2
Register set.
Direction = Write: The Arbitration bits (Iden Dir + Xtd + MsgVal) will be transferred from
the IF1/IF2 Register set to the message object addressed by Message Number (Bits [7:0]).
20
Control
Access Control bits.
0
Control bits will not be changed.
1
Direction = Read: The Message Control bits will be transferred from the message object
addressed by Message Number (Bits [7:0]) to the corresponding IF1/IF2 Register set.
Direction = Write: The Message Control bits will be transferred from the IF1/IF2 Register set to
the message object addressed by Message Number (Bits [7:0]).
If the TxRqst/NewDat bit in this register (Bit [18]) is set, the TxRqst/NewDat bit in the IF1/IF2
Message Control Register will be ignored.
19
ClrIntPnd
Clear Interrupt Pending bit.
0
IntPnd bit will not be changed.
1
Direction = Read: Clears IntPnd bit in the message object.
Direction = Write: This bit is ignored. Copying of IntPnd flag from IF1/IF2 Registers to Message
RAM can be controlled by only the Control flag (Bit [20]).
18
TxRqst/NewDat
Access Transmission Request bit.
0
Direction = Read: NewDat bit will not be changed.
Direction = Write: TxRqst/NewDat bit will be handled according to the Control bit.
1
Direction = Read: Clears NewDat bit in the message object.
Direction = Write: Sets TxRqst/NewDat in the message object.
Note:
If a CAN transmission is requested by setting TxRqst/NewDat in this register, the
TxRqst/NewDat bits in the message object will be set to 1 and independent of the values in
IF1/IF2 Message Control Register.
A read access to a message object can be combined with the reset of the control bits IntPnd
and NewDat. The values of these bits transferred to the IF1/IF2 Message Control Register
always reflect the status before resetting them.
17
Data A
Access Data Bytes 0–3.
0
Data Bytes 0–3 will not be changed.
1
Direction = Read: The Data Bytes 0–3 will be transferred from the message object addressed
by the Message Number (Bits [7:0]) to the corresponding IF1/IF2 Register set.
Direction = Write: The Data Bytes 0–3 will be transferred from the IF1/IF2 Register set to the
message object addressed by the Message Number (Bits [7:0]).
Note:
The duration of the message transfer is independent of the number of bytes to be
transferred.