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Time Segment 2: This segment represents the PHASE_SEG2 of the CAN standard. It can be programmed by setting the TSEG2
parameter to be 2 to 8 time quanta long.
SYNC_SEG
Transmit Point
Syntax
SYNC_SEG
Transmit Point
Sample Point
The Synchronization Jump Width
The above parameters are set by programming the MSCAN Bus Timing Registers (CANBTR0, CANBTR1) (see
Control Register 0 (CANCTL0)—MBAR + 0x0900 / 0x980
/
0x985).
Table 19-34
gives an overview of the CAN compliant segment settings and the related parameter values.
It is the user's responsibility to ensure the bit time settings are in compliance with the CAN standard.
Table 19-34. CAN Standard Compliant Bit Time Segment Settings
Time Segment 1
5 .. 10
4 .. 11
1. Reference the Bosch CAN 2.0A/B protocol specification dated September 1991 for bit timing.
Freescale Semiconductor
Bit
Þ
Rate
=
---------------------------------------------------------------------------------------- -
(
number
NRZ Signal
Time Segment 1
(PROP_SEG + PHASE_SEG1)
1
4 ... 16
8 ... 25 Time Quanta
= 1 Bit Time
Figure 19-8. Segments within the Bit Time
Table 19-33. Time Segment Syntax
System expects transitions to occur on the 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 bus at this point. If the three
samples per bit option is selected, then this point marks the position
of the third sample.
1
can be programmed in a range of 1 to 4 time quanta by setting the SJW parameter.
and
Section 19.5.6, MSCAN Bus Timing Register 1 (CANBTR1)—MBAR + 0x0905
TSEG1
Time Segment 2
4 .. 9
2
3 .. 10
3
MPC5200B Users Guide, Rev. 1
f
Tq
Þ
of
Þ
Time
Þ
Quanta
Time Segment 2
(PHASE_SEG2)
Sample Point
(single or triple sampling)
Description
NOTE
Synchronization
TSEG2
Jump Width
1
2
Functional Description
)
2 ... 8
Section 19.5.3, MSCAN
SJW
1 .. 2
0 .. 1
1 .. 3
0 .. 2
19-33
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