The Propagation Time Segment; Programmable Ranges Required By Can Protocol - Texas Instruments Concerto F28M35 Series Technical Reference Manual

Table of Contents

Synchronization Jump Width (SJW)

NOTE: For proper functionality of the CAN network, the physical delay times and the oscillator's

tolerance range have to be considered.

23.12.1.1 Synchronization Segment

The Synchronization Segment (Sync_Seg) is the part of the bit time where edges of the CAN bus level are

expected to occur. If an edge occurs outside of Sync_Seg, its distance to the Sync_Seg is called the

phase error of this edge.

23.12.1.2 Propagation Time Segment

This part of the bit time is used to compensate physical delay times within the CAN network. These delay

times consist of the signal propagation time on the bus and the internal delay time of the CAN nodes.

Any CAN node synchronized to the bit stream on the CAN bus can be out of phase with the transmitter of

the bit stream, caused by the signal propagation time between the two nodes. The CAN protocol's

nondestructive bitwise arbitration and the dominant acknowledge bit provided by receivers of CAN

messages require that a CAN node transmitting a bit stream must also be able to receive dominant bits

transmitted by other CAN nodes that are synchronized to that bit stream. The example in

shows the phase shift and propagation times between two CAN nodes.

Delay A_to_B >= node output delay(A) + bus line delay(A B) + node input delay(B)

Prop_Seg >= Delay A_to_B + Delay B_to_A

Prop_Seg >= 2 • [max(node output delay+ bus line delay + node input delay)]

SPRUH22I – April 2012 – Revised November 2019

Submit Documentation Feedback

Table 23-1. Programmable Ranges Required by CAN Protocol

Figure 23-12. The Propagation Time Segment

Delay A_to_B

Synchronization of bus input to CAN_CLK

Compensates for the physical delay times

May be lengthened temporarily by synchronization

May be shortened temporarily by synchronization

May not be longer than either Phase Buffer Segment

M3 Controller Area Network (CAN)

CAN Bit Timing

Figure 23-12

Chapters

Table of Contents