EP80579 Datasheet, PDF (1578/1916 Pages) Intel Corporation – Intel® EP80579 Integrated Processor Product Line

Intel^® EP80579 Integrated Processor
Each member of CAN network can use different timing parameters to achieve the same
bit rate. As shown in Figure 39-6 each segment is defined in terms of time quantum
(tq).
Figure 39-6. CAN Timing Parameters
Synchronization
Segment
Propagation
Delay Segment
1
Phase Buffer
Segment 1
Phase Buffer
Segment 2
Time Quanta
Sample Point
Bit Time
The time quantum value is the basic unit of the bit time and is determined by the CAN
controller system clock frequency and the bit scaler.
tq = Bit_Scaler / CAN clock frequency.
For a given bit rate that the CAN requires, the Bit_Scaler can be changed to meet the
recommended values of phase buffer segments and synchronization jump width.
The CiA (CAN in automation) draft standard 102 version 2.0 defines the content of the
physical layer and the basic characteristics of the physical medium, for communication
according to the Controller Area Network protocol specification (CAN) between different
types of electronic modules in general industrial applications.
Table 39-1. CiA Recommended bit rate and timing Parameters (Sheet 1 of 2)
Bit Rate
(kbits/s)
1000
800
500
250
125
50
20
Bus
Length
(m)
25
50
100
250
500
1000
2500
Nominal
Bit Time
tb (us)
1
1.25
2
4
8
20
50
Number of
Time Quanta
per Bit
8
10
16
16
16
16
16
Length of
Time
Quantum Tq
(us)
0.125
0.125
0.125
0.250
0.500
1.25
3.125
Location
of Sample
Point wrt
tq
Location
of Sample
Point (us)
Comments
6 Tq
8 Tq
14 Tq
14 Tq
14 Tq
14 Tq
14 Tq
0.75
1
1.75
3.5
7
17.5
43.75
max 40m
max 1km
Has to be supported by
all modules
Intel^® EP80579 Integrated Processor Product Line Datasheet
1578
August 2009
Order Number: 320066-003US