NUC970 Technical Reference Manual
Publication Release Date: Dec. 15, 2015
- 812 -
Revision V1.30
NUC97
0
T
E
CHNIC
A
L
RE
F
E
RE
N
CE
MA
NUA
L
IFn Command Request Register (CAN_IFn_CREQ)
Register
Offset
R/W
Description
Reset Value
CAN_IFn_CREQ
0x20/0x80 R/W
IFn Command Request Register
0x0000_0001
31
30
29
28
27
26
25
24
Reserved
23
22
21
20
19
18
17
16
Reserved
15
14
13
12
11
10
9
8
Busy
Res
7
6
5
4
3
2
1
0
Res
Message Number
Bits
Description
[15]
Busy
Busy Flag
0 = Read/write action has finished.
1 = Writing to the IFn Command Request Register is in progress. This bit can only be read by
the software.
[14:6]
Reserved
Reserved.
[5:0]
Message Number
Message Number
0x01-0x20: Valid Message Number, the Message Object in the Message
RAM is selected for data transfer.
0x00: Not a valid Message Number, interpreted as 0x20.
0x21-0x3F: Not a valid Message Number, interpreted as 0x01-0x1F.
A message transfer is started as soon as the application software has written the message number to
the Command Request Register. With this write operation, the Busy bit is automatically set to notify
the CPU that a transfer is in progress. After a waiting time of 3 to 6 APB_CLK periods, the transfer
between the Interface Register and the Message RAM is completed. The Busy bit is cleared.
Note:
When a Message Number that is not valid is written into the Command Request Register, the
Message Number will be transformed into a valid value and that Message Object will be transferred.