LAN9353 Datasheet, PDF (395/523 Pages) Microchip Technology – Interfaces at up to 200Mbps via Turbo MII

LAN9353
pensated by the transparent clock method described above. Using the round trip time and accounting for the residence
time reported, the slave can calculate the mean delay from the master. Each slave sends and receives its own mes-
sages and calculates its own delay. While the end-to-end method is the simplest, it does add burden on the master since
the master must process packets from each slave in the system. This is amplified when boundary clocks are replaced
by transparent clocks. Also, the end-to-end delays must be recalculated if there is a change in the network topology.
Using the peer-to-peer method, packets are exchanged only between adjacent master, slaves and transparent clocks.
Each peer pair calculates the receive path delay. As time synchronization packets are forwarded between the master
and the slave, the transparent clock adds the pre-measured receive path delay into the residence time. The final
receiver adds its receive path delay. Using the peer-to-peer method, the full path delay is accounted for without the mas-
ter having to service each slave. The peer-to-peer method better supports network topology changes since each path
delay is kept up-to-date regardless of the port status.
The PTP implementation consists of the following major function blocks:
• PTP Timestamp and Residence Time Correction
This block provides time stamping and packet modification functions.
• 1588 Clock
This block provides a tunable clock that is used as the time source for all PTP timestamp related functions.
• 1588 Clock Events
This block provides clock comparison-based interrupt generation and timestamp related GPIO event generation.
• 1588 GPIOs
This block provides for time stamping GPIO input events and for outputting clock comparison-based interrupt sta-
tus.
• 1588 Interrupt
This block provides interrupt generation, masking and status.
• 1588 Registers
This block provides contains all configuration, control and status registers.
 2015 Microchip Technology Inc.
DS00001925A-page 395