DCAN Registers
23.4.4 BTR Register (offset = 0Ch) [reset = 2301h]
BTR is shown in
and described in
.
This register is only writable if CCE and Init bits in the CAN control register are set. The CAN bit time may
be programmed in the range of 8 to 25 time quanta. The CAN time quantum may be programmed in the
range of 1 to1024 CAN_CLK periods. With a CAN_CLK of 8 MHz and BRPE = 0x00, the reset value of
0x00002301 configures the DCAN for a bit rate of 500kBit/s.
Figure 23-22. BTR Register
31
30
29
28
27
26
25
24
Reserved
R-0h
23
22
21
20
19
18
17
16
Reserved
BRPE
R-0h
R-0h
15
14
13
12
11
10
9
8
Reserved
TSeg2
TSeg1
R-0h
R/WP-2h
R/WP-3h
7
6
5
4
3
2
1
0
SJW
BRP
R/WP-0h
R/WP-1h
LEGEND: R/W = Read/Write; R = Read only; W1toCl = Write 1 to clear bit; -n = value after reset
Table 23-17. BTR Register Field Descriptions
Bit
Field
Type
Reset
Description
31-20
Reserved
R
0h
19-16
BRPE
R
0h
Baud rate prescaler extension.
Valid programmed values are 0 to 15.
By programming BRPE the baud rate prescaler can be extended to
values up to 1024.
15
Reserved
R
0h
14-12
TSeg2
R/WP
2h
Time segment after the sample point.
Valid programmed values are 0 to 7.
The actual TSeg2 value which is interpreted for the bit timing will be
the programmed TSeg2 value + 1.
11-8
TSeg1
R/WP
3h
Time segment before the sample point.
Valid programmed values are 1 to 15.
The actual TSeg1 value interpreted for the bit timing will be the
programmed TSeg1 value + 1.
7-6
SJW
R/WP
0h
Synchronization Jump Width.
Valid programmed values are 0 to 3.
The actual SJW value interpreted for the synchronization will be the
programmed SJW value + 1.
5-0
BRP
R/WP
1h
Baud rate prescaler.
Value by which the CAN_CLK frequency is divided for generating the
bit time quanta.
The bit time is built up from a multiple of this quanta.
Valid programmed values are 0 to 63.
The actual BRP value interpreted for the bit timing will be the
programmed BRP value + 1.
3930
Controller Area Network (CAN)
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated