K60P100M100SF2RM Datasheet, PDF (1209/1809 Pages) Freescale Semiconductor, Inc – K60 Sub-Family Reference Manual

44.4.10.4 Time Synchronization
Chapter 44 10/100-Mbps Ethernet MAC (ENET)
The adjustable timer module is available to synchronize the local clock of a node to a
remote master. It implements a free running 32-bit counter, and also contains an
additional correction counter.
The correction counter increases or decreases the rate of the free running counter,
enabling very fine granular changes of the timer for synchronization, yet adding only
very low jitter when performing corrections.
The application software implements, in a slave scenario, the required control algorithm
setting the correction to compensate for local oscillator drifts and locking the timer to the
remote master clock on the network.
The timer and all timestamp-related information should be configured to show the true
nanoseconds value of a second (i.e. the timer is configured to have a period of one
second). Hence, the values range from 0 to (1 × 10⁹)-1. In this application, the seconds
counter is implemented in software using an interrupt function that is executed when the
nanoseconds counter wraps at 1 × 10⁹.
44.4.11 FIFO Thresholds
The core FIFO thresholds are fully programmable to dynamically change the FIFO
operation.
For example, store and forward transfer can be enabled by a simple change in the FIFO
threshold registers.
The thresholds are defined in 64-bit words.
K60 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc.
1209