Transmit Clocks - 3.1 English - PG314

The following describes the transmit clocks in the MRMAC.

tx_core_clk[3:0]

This internal high-speed clock drives the bulk of the MRMAC transmit datapath. This per-port clock must be generated by the GT transceiver.

tx_alt_serdes_clk[3:0]

This is an internally-used clock derived from the primary SerDes clocks. These clocks run at exactly half the tx_core_clk[3:0] frequencies. This clock is typically generated by the IP Wizard.

tx_flexif_clk[3:0]

This is used by the flex interface. When the Flex I/F is active, tx_flexif_clk[N] must operate at a frequency ≥ 1/2 of the corresponding tx_core_clk[N] frequency.

tx_axi_clk[2][0]

AXI4-Stream interface clocks. In addition to clocking the AXI4-Stream interface in independent clocking mode, the tx_axi_clk[2][0] clocks are also used only to clock certain statistics and flow control signals. The tx_axi_clk[2][0] clocks must operate at a frequency high enough to maintain the desired data rate across the AXI4-Stream bus, which is tx_axi_clk[N] must be greater than or equal to 1/2 of the corresponding tx_core_clk[N] frequency.

tx_ts_clk[3:0]

This clock drives the 1588 timestamping signaling. The MRMAC timestamp timers attempt to synchronize with the external time-of-day source which is running on this clock.