PXN20RM Datasheet, PDF (921/1376 Pages) Freescale Semiconductor, Inc – PXN20 Microcontroller

NRZ Signal
Controller Area Network (FlexCAN)
SYNCSEG
Time Segment 1
(PROPSEG + PSEG1 + 2)
Time Segment 2
(PSEG2 + 1)
1
4 ... 16
8 ... 25 Time Quanta
= 1 Bit Time
2 ... 8
Transmit Point
Sample Point
(single or triple sampling)
Figure 29-16. Segments within the Bit Time
Table 29-17. Time Segment Syntax
Syntax
SYNCSEG
Transmit Point
Sample Point
Description
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.
Table 29-18 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. For bit time calculations, use an information
processing time (IPT) of 2, which is the value implemented in the FlexCAN
module.
Table 29-18. CAN Standard Compliant Bit Time Segment Settings
Time Segment 1
5 .. 10
4 .. 11
5 .. 12
6 .. 13
7 .. 14
Time Segment 2
2
3
4
5
6
Resynchronization
Jump Width
1 .. 2
1 .. 3
1 .. 4
1 .. 4
1 .. 4
Freescale Semiconductor
PXN20 Microcontroller Reference Manual, Rev. 1
29-37