Timer Block Diagram - 2.3 English

The architecture of the PTP timer is shown in the following figure.

The heart of the timer is an accumulator with a programmable periodic increment. You can specify the initial timer value and the increment value (the increment value defaults to the nominal value based on the configured data rate). These values can be further adjusted, if necessary, using various optional correction methods (including phase and frequency adjustments) to achieve improved accuracy between the system timer and the master TOD timer.

The main elements of the system timer include:

system_timer

DCMAC Subsystem timer, source of generated timestamps.

Timer Increment

The amount by which system_timer is incremented each clock period. The amount of increment can be set or adjusted as needed to synchronize the system_timer with the external master clock.

Overwrite

A one-shot overwrite of the system_timer value, triggered by a transition of ptp_st_sync while ptp_st_overwrite input signal is set.

Timestamp

The generated timestamp to the system, micro-adjusted to account for any desired latency by the value ctl_ptp_latency_adj.