Low Latency E-Tile 40G Ethernet Intel® FPGA IP Design Example User Guide

ID 683747
Date 6/22/2020
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2.7. Design Example Interface Signals

The Low Latency E-Tile 40G Ethernet testbench is self-contained and does not require you to drive any input signals.

Table 7.   Low Latency E-Tile 40G Ethernet Hardware Design Example Interface Signals
Signal Direction Comments
clk50 Input

This clock is driven by the board oscillator.

  • Drive at 50 MHz on Intel® Stratix® 10 board.
  • Drive at 100 MHz on Intel® Agilex™ board.

The hardware design example routes this clock to the input of an IOPLL on the device and configures the IOPLL to drive a 100 MHz clock internally.

clk_ref Input Drive at 156.25 MHz.
cpu_resetn Input Resets the IP core. Active low. Drives the global hard reset csr_reset_n to the IP core.
tx_serial[3:0] Output Transceiver PHY output serial data.
rx_serial[3:0] Input Transceiver PHY input serial data.
user_led[7:0] Output Status signals. The hardware design example connects these bits to drive LEDs on the target board. Individual bits reflect the following signal values and clock behavior:
  • [0]: Main reset signal to IP core
  • [1]: Divided version of clk_ref
  • [2]: Divided version of clk50
  • [3]: Divided version of 100 MHz status clock
  • [4]: tx_lanes_stable
  • [5]: rx_block_lock
  • [6]: rx_am_lock
  • [7]: rx_pcs_ready