DCAN Control Registers
1099
SPNU503C – March 2018
Copyright © 2018, Texas Instruments Incorporated
Controller Area Network (DCAN) Module
23.17.19 IF1/IF2 Command Registers (DCAN IF1CMD, DCAN IF2CMD)
The IF1/IF2 Command Register configure and Initiate the transfer between the IF1/IF2 Register sets and
the Message RAM. It is configurable which portions of the message object should be transferred.
A transfer is started when the CPU writes the message number to bits [7:0] of the IF1/IF2 Command
Register. With this write operation, the Busy bit is automatically set to 1 to indicate that a transfer is in
progress.
After 4 to 14 VBUS clock cycles, the transfer between the Interface Register and the Message RAM will
be completed and the Busy bit is cleared. The maximum number of cycles is needed when the message
transfer concurs with a CAN message transmission, acceptance filtering, or message storage.
If the CPU writes to both IF1/IF2 Command Registers consecutively (request of a second transfer while
first transfer is still in progress), the second transfer will start after the first one has been completed.
NOTE:
While the Busy bit is 1, IF1/IF2 Register sets are write protected.
For debug support, the auto clear functionality of the IF1/IF2 Command Registers (clear of
DMA Active flag by r/w) is disabled during Debug/Suspend mode.
If an invalid Message Number is written to bits [7:0] of the IF1/IF2 Command Register, the
Message Handler may access an implemented (valid) message object instead.
Figure 23-52. IF1 Command Registers (DCAN IF1CMD) [offset = 100h]
31
24
Reserved
R-0
23
22
21
20
19
18
17
16
WR_RD
Mask
Arb
Control
ClrIntPnd
TxRqst/NewDat
Data A
Data B
R/WP-0
R/WP-0
R/WP-0
R/WP-0
R/WP-0
R/WP-0
R/WP-0
R/WP-0
15
14
13
8
Busy
DMA Active
Reserved
R-0
R/WP/C-0
R-0
7
0
Message Number
R/WP-1h
LEGEND: R/W = Read/Write; R = Read only; WP = Protected Write (protected by Busy bit); C = Clear by IF1 Access; -
n
= value after reset
Figure 23-53. IF2 Command Registers (DCAN IF2CMD) [offset = 120h]
31
24
Reserved
R-0
23
22
21
20
19
18
17
16
WR_RD
Mask
Arb
Control
ClrIntPnd
TxRqst/NewDat
Data A
Data B
R/WP-0
R/WP-0
R/WP-0
R/WP-0
R/WP-0
R/WP-0
R/WP-0
R/WP-0
15
14
13
8
Busy
DMA Active
Reserved
R-0
R/WP/C-0
R-0
7
0
Message Number
R/WP-1h
LEGEND: R/W = Read/Write; R = Read only; WP = Protected Write (protected by Busy bit); C = Clear by IF1 Access; -
n
= value after reset
