Register 4: CAN Bit Timing (CANBIT), offset 0x00C
This register is used to program the bit width and bit quantum. Values are programmed to the system
clock frequency. This register is write-enabled by setting the CCE and INIT bits in the CANCTL
register. See “Bit Time and Bit Rate” on page 377 for more information.
CAN Bit Timing (CANBIT)
CAN0 base: 0x4004.0000
CAN1 base: 0x4004.1000
CAN2 base: 0x4004.2000
Offset 0x00C
Type R/W, reset 0x0000.2301
16171819202122232425262728293031
reserved
ROROROROROROROROROROROROROROROROType
0000000000000000Reset
0123456789101112131415
BRPSJWTSEG1TSEG2
reserved
R/WR/WR/WR/WR/WR/WR/WR/WR/WR/WR/WR/WR/WR/WR/WROType
1000000011000100Reset
DescriptionResetTypeNameBit/Field
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
0x0000ROreserved31:15
Time Segment after Sample Point
0x00-0x07: The actual interpretation by the hardware of this value is
such that one more than the value programmed here is used.
So, for example, a reset value of 0x2 defines that there is 3 (2+1) bit
time quanta defined for Phase_Seg2 (see Figure 14-4 on page 378).
The bit time quanta is defined by the BRP field.
0x2R/WTSEG214:12
Time Segment Before Sample Point
0x00-0x0F: The actual interpretation by the hardware of this value is
such that one more than the value programmed here is used.
So, for example, the reset value of 0x3 defines that there is 4 (3+1) bit
time quanta defined for Phase_Seg1 (see Figure 14-4 on page 378).
The bit time quanta is define by the BRP field.
0x3R/WTSEG111:8
(Re)Synchronization Jump Width
0x00-0x03: The actual interpretation by the hardware of this value is
such that one more than the value programmed here is used.
During the start of frame (SOF), if the CAN controller detects a phase
error (misalignment), it can adjust the length of TSEG2 or TSEG1 by the
value in SJW. So the reset value of 0 adjusts the length by 1 bit time
quanta.
0x0R/WSJW7:6
391June 22, 2010
Texas Instruments-Production Data
Stellaris® LM3S8530 Microcontroller
