MC9S12XD256MAL Datasheet, PDF (466/1348 Pages) Freescale Semiconductor, Inc – Freescale’s Scalable Controller Area Network

Chapter 10 Freescale’s Scalable Controller Area Network (S12MSCANV3)
Syntax
SYNC_SEG
Transmit Point
Sample Point
Table 10-34. Time Segment Syntax
Description
System expects transitions to occur on the CAN bus during this
period.
A node in transmit mode transfers a new value to the CAN bus at
this 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 10.3.2.3, “MSCAN Bus Timing Register 0 (CANBTR0)”
and Section 10.3.2.4, “MSCAN Bus Timing Register 1 (CANBTR1)”).
Table 10-35 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 10-35. CAN Standard Compliant Bit Time Segment Settings
Time Segment 1
5 .. 10
4 .. 11
5 .. 12
6 .. 13
7 .. 14
8 .. 15
9 .. 16
TSEG1
4 .. 9
3 .. 10
4 .. 11
5 .. 12
6 .. 13
7 .. 14
8 .. 15
Time Segment 2
2
3
4
5
6
7
8
TSEG2
1
2
3
4
5
6
7
Synchronization
Jump Width
1 .. 2
1 .. 3
1 .. 4
1 .. 4
1 .. 4
1 .. 4
1 .. 4
SJW
0 .. 1
0 .. 2
0 .. 3
0 .. 3
0 .. 3
0 .. 3
0 .. 3
10.4.4 Modes of Operation
10.4.4.1 Normal Modes
The MSCAN module behaves as described within this specification in all normal system operation modes.
10.4.4.2 Special Modes
The MSCAN module behaves as described within this specification in all special system operation modes.
MC9S12XDP512 Data Sheet, Rev. 2.21
466
Freescale Semiconductor