This section describes the ports relating to the operation of the IEEE 1588 Timestamping function. The timestamping interface can be coupled with either the Flex I/F or the AXI4-Stream interface, depending on which interface is active.
When the AXI4-Stream interface is
active, the timestamping signals are clocked by the AXI clock. When the Flex I/F is active
and the AXI4-Stream interface is disabled, the timestamp
interface still uses the AXI clock. For this reason,
the flexif_clk should drive the axi_clk port when the Flex I/F is in use.