MC9S12GRMV1 Datasheet, PDF (626/1292 Pages) Freescale Semiconductor, Inc – MC9S12G Family Reference Manual and Data Sheet

Freescale’s Scalable Controller Area Network (S12MSCANV3)
Table 18-36. Time Segment Syntax
Syntax
SYNC_SEG
Transmit Point
Sample Point
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 2.0A/B 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 18.3.2.3, “MSCAN Bus Timing Register 0 (CANBTR0)”
and Section 18.3.2.4, “MSCAN Bus Timing Register 1 (CANBTR1)”).
Table 18-37 gives an overview of the Bosch CAN 2.0A/B specification 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 18-37. Bosch CAN 2.0A/B 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
18.4.4 Modes of Operation
18.4.4.1 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.
MC9S12G Family Reference Manual, Rev.1.23
628
Freescale Semiconductor