Freescale’s Scalable Controller Area Network (S12MSCANV3)
Table 8-36. Time Segment Syntax
Syntax
Description
System expects transitions to occur on the CAN bus during this
period.
SYNC_SEG
A node in transmit mode transfers a new value to the CAN bus at
this point.
Transmit Point
Sample Point
A node in receive mode samples the CAN bus at this point. If the
three samples per bit option is selected, then this point marks the
position of the third sample.
The synchronization jump width (see the Bosch CAN specification for details) can be programmed in a
range of 1 to 4 time quanta by setting the SJW parameter.
The SYNC_SEG, TSEG1, TSEG2, and SJW parameters are set by programming the MSCAN bus timing
registers (CANBTR0, CANBTR1) (see Section 8.3.2.3, “MSCAN Bus Timing Register 0 (CANBTR0)”
and Section 8.3.2.4, “MSCAN Bus Timing Register 1 (CANBTR1)”).
Table 8-37 gives an overview of the CAN compliant segment settings and the related parameter values.
NOTE
It is the user’s responsibility to ensure the bit time settings are in compliance
with the CAN standard.
Table 8-37. CAN Standard Compliant Bit Time Segment Settings
Synchronization
Time Segment 1
TSEG1
Time Segment 2
TSEG2
SJW
Jump Width
5 .. 10
4 .. 11
5 .. 12
6 .. 13
7 .. 14
8 .. 15
9 .. 16
4 .. 9
3 .. 10
4 .. 11
5 .. 12
6 .. 13
7 .. 14
8 .. 15
2
3
4
5
6
7
8
1
2
3
4
5
6
7
1 .. 2
1 .. 3
1 .. 4
1 .. 4
1 .. 4
1 .. 4
1 .. 4
0 .. 1
0 .. 2
0 .. 3
0 .. 3
0 .. 3
0 .. 3
0 .. 3
8.4.4
Modes of Operation
8.4.4.1
Normal System Operating Modes
The MSCAN module behaves as described within this specification in all normal system operating modes.
Write restrictions exist for some registers.
S12P-Family Reference Manual, Rev. 1.13
Freescale Semiconductor
295
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