IEEE 1588 synchronization upgrade of Remote IO Unit

The M50 is designed to enhance the Ethernet interface with a minimum of design change from a traditional Ethernet circuitry. The module can be a drop-in replacement for an existing PHY circuit. As in the remote I/O application in figure 1.

Figure 1: Replacing the PHY of a Remote IO unit

The PCB integration work is simply to remove the existing PHY and its peripheral passive components. The M50 connects directly to the magnetics and connector on one side (Tx, Rx, Link LED etc). The other side connects to the reduced MII interface of the processor. See Figure 2.

Figure 2: PHY upgrade schematics

In this application the developer can chose to use e.g. the SPI interface to control the basic performance of the module, or a telnet port. Without such control inputs the unit operates on its default parameters. If there is a centralized timing controller in the network, the M50 can be monitored and controlled remotely. Without local control this is an integration example on level A (see Conemtech Level of Integration).

For a reliable time and frequency output the M50 requires a Precise Time Protocol (PTP) Grandmaster in the network. The on-board crystal oscillator can provide short term holdover. Extended holdover times can be achieved with an external oscillator.