DESIGN OF A CUSTOM ASIC INCORPORATING CAN™ AND 1 ...

Figure 3.12 Propagation Delay Between Nodes [23].
Segment Name
Table 3.5 Types of Segments and Their Roles [19].
Roles of Segment Number of t Q ’s
Synchronization Segment
(SYNC_SEG)
Propagation Time Segment
(PROP_SEG)
Phase Buffer Segment1
(PHASE_SEG1)
Phase Buffer Segment2
(PHASE_SEG2)
Resynchronization Jump
Width (RJW) (See Section
3.6.5)
Multiple units connected to the bus are timed
to be coincident during the interval of this
segment as they send or receive a frame. A
recessive to dominant or a dominant to
recessive transition edge is expected to exist in
this segment.
This segment absorbs physical delays on the
network, which include an output delay of the
transmit unit, a propagation delay of signal on
the bus, and an input delay of the receive unit.
The duration of this segment is twice the sum
of each delay time.
This segment is used to correct for errors when
signal edges do occur within SYNC_SEG.
This segment is used to correct for errors when
signal edges do occur within SYNC_SEG.
Since each unit is operating with their own
clock, even a minute clock error in each node
will accumulate. This segment absorbs such
an error. To absorb a clock error, add or
subtract within the Resynchronization Jump
Width (RJW) setup range for PHASE_SEG1
and PHASE_SEG2. The larger the values of
PHASE_SEG1 and PHASE_SEG2, the greater
the tolerance, but the communication speed
slows down.
Some units may get out of sync for reasons of
a drift in clock frequency or a delay in
transmission path. RJW is the maximum
width for which this out-of-sync is corrected.
68
1
1 – 8
1 – 8
PHASE_SEG1 or
IPT, whichever is
larger.
1 – 4 and
≤PHASE_SEG1
8-25 t Q ’s