SPRUII0F May 2019 – June 2024 TMS320F28384D , TMS320F28384D-Q1 , TMS320F28384S , TMS320F28384S-Q1 , TMS320F28386D , TMS320F28386D-Q1 , TMS320F28386S , TMS320F28386S-Q1 , TMS320F28388D , TMS320F28388S
Ethernet module supports different clock types defined in IEEE 1588-2008. The Ethernet module supports the following clock types:
Ordinary Clock: The ordinary clock has a single PTP state and a single physical port. In a domain, an ordinary clock supports a single copy of the protocol.
The ordinary clock in a domain supports a single copy of the protocol. The ordinary clock has a single PTP state and a single physical port. In typical industrial automation applications, an ordinary clock is associated with an application device such as a sensor or an actuator. In telecom applications, the ordinary clock can be associated with a timing demarcation device.
The ordinary clock can be a grandmaster or a slave clock. The ordinary clock supports the following features:
Table 43-9 shows the messages for which you can take the timestamp snapshot on the receive side for master and slave nodes.
Master | Slave |
---|---|
Delay_Reg | SYNC |
For an ordinary clock, you can take the snapshot of either of the following PTP message types: version 1 or version 2. You cannot take the snapshots for both PTP message types. You can take the snapshot by setting the TSVER2ENA bit and selecting the snapshot mode in MAC_Timestamp_Control.
Boundary Clock: The boundary clock typically has several physical ports communicating with the network. The messages related to synchronization, master-slave hierarchy, and signaling terminate in the protocol engine of the boundary clock and such messages are not forwarded. The PTP message type status given by the MAC helps you to identify the type of message and take appropriate action.
The boundary clock is similar to the ordinary clock except for the following features:
End-to-End Transparent Clock: The end-to-end transparent clock supports the end-to-end delay measurement mechanism between the slave clocks and the master clock. The end-to-end transparent clock forwards all messages like normal bridge, router, or repeater. The residence time of a PTP packet is the time taken by the PTP packet from the Ingress port to the Egress port.
The residence time of a SYNC packet inside the end-to-end transparent clock is updated in the correction field of the associated Follow_Up PTP packet before it is transmitted. Similarly, the residence time of a Delay_Req packet, inside the end-to-end transparent clock, is updated in the correction field of the associated Delay_Resp PTP packet before it is transmitted. Therefore, the snapshot must be taken at both Ingress and Egress ports only for the messages mentioned in Table 43-10. You can take the snapshot by setting the SNAPTYPSEL bits to 10 in the MAC_Timestamp_Control register.
PTP Messages |
---|
SYNC |
Delay_Reg |
Peer-to-Peer Transparent Clock: In the peer-to-peer transparent clock, the computation of the link delay is based on an exchange of Pdelay_Req, Pdelay_Resp, and Pdelay_Resp_Follow_Up messages with the link peer.
The peer-to-peer transparent clock differs from the end-to-end transparent clock in the way the peer-to-peer transparent clock corrects and handles the PTP timing messages. In all other aspects, the peer-to-peer transparent clock is identical to the end-to-end transparent clock.
In the peer-to-peer transparent clock, the computation of the link delay is based on an exchange of Pdelay_Req, Pdelay_Resp, and Pdelay_Resp_Follow_Up messages with the link peer. The residence time of the Pdelay_Req and the associated Pdelay_Resp packets is added and inserted into the correction field of the associated Pdely_Resp_Followup packet. Therefore, support for taking the snapshot for the event messages related to Pdelay is added as shown in Table 43-11.
You can take the snapshot by setting the SNAPTYPESEL bit to 11 in MAC_Timestamp_Control register.
PTP Messages |
---|
SYNC |
PDelay_reg |
Pdelay_Resp |
Delay Request-Response Mechanism: The system or network is classified into the master and slave nodes for distributing the timing and clock information.
The system or network is classified into the master and slave nodes for distributing the timing and clock information. Figure 43-10 shows the process that PTP uses for synchronizing a slave node to a master node by exchanging PTP messages.
Most of the PTP implementation is done in the software above the Ethernet/UDP layer. However, the hardware support is required to capture the exact time when specific PTP packets enter or leave the Ethernet port at the MII interface. This timing information must be captured and returned to the software for proper implementation of PTP with high accuracy.