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This board is a variant of the FPGA rack board, but with 4 Ethernet connectors.

Type FPGA Rack Schematic UCF Description
V1.0 FPGA Rack Ethernet4 V1.0 FPGA-Rack-Ethernet4 v1.0 Schematic PDF FPGA-Rack v1.0 UCF Files There are different FPGA mounted: Spartan 6 XC6SLX45, Spartan 6 XC6SLX100, Spartan 6 XC6SLX150

The board is compatible with the FPGA Rack Backplane for interconnecting different boards with the help of the HES-SO Backplane Bus and the HES-SO VME IP Core. It holds 4 Ethernet connectors, each connected to an independent KSZ8041NL PHY.


PHY clocks

All 4 PHYs receive the same 25 MHz clock. This clock signal can be sourced from:

  • the quartz oscillator closest to the PHYs (CLK_PHY_25M)
  • the FPGA (CLK_PHY_FPGA, pin AB13).

The FPGA can generate the PHY clock from

  • a 106.25 MHz quartz (CLK_106_25M, pin Y13)
  • the PHY quartz oscillator (CLK_PHY_25M, pin AA12)
  • one of the PHY Rx or Tx clocks (ETHA_RX_CLK, ETHA_TX_CLK, ETHB_RX_CLK, …)

The last possibility is foreseen to synchronise the clocks of slave Ethernet ports to the one of a master port.

Management Data Input Output (MDIO)

The serial Management Data Input Output (MDIO) interface is connected independently from each PHY to the FPGA.

Serial ports

The FPGA has 3 serial port connections:

  • one via an FT232RL RS232 to USB interface (USB_TXD, USB_RXD and 6 more lines)
  • 2 via a level translator
    • the first goes to a flat cable connector (UART_TXD0, UART_RXD0)
    • the second to the JTAG mini connector (UART_TXD1, UART_RXD01)

USB serial interface

The USB serial interface powers the board if jumper JP1 is set on the USB_5V side.

It provides a serial port and a JTAG interface. The serial port is connected directly to the FPGA. The JTAG interface can be connected to the FPGA programming lines via zero-Ohm resistors. This programming mode has not been tested yet.

JTAG connector

The HEI 10-pin JTAG connector provides:

  • a 3.3 V power supply
  • 4 JTAG signals for FPGA and Flash programmation
  • a minimal serial port (Rx and Tx)
  • 2 FPGA I/O lines
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