The Nexys4 board is a complete, ready-to-use digital circuit development platform based on the latest Artix-7™ Field Programmable Gate Array (FPGA) from Xilinx. With its large, high-capacity FPGA (Xilinx part number XC7A100T-1CSG324C), generous external memories, and collection of USB, Ethernet, and other ports, the Nexys4 can host designs ranging from introductory combinational circuits to powerful embedded processors. Several built-in peripherals, including an accelerometer, temperature sensor, MEMs digital microphone, a speaker amplifier, and a lot of I/O devices allow the Nexys4 to be used for a wide range of designs without needing any other components.

The Artix-7 FPGA is optimized for high performance logic, and offers more capacity, higher performance, and more resources than earlier designs. Artix-7 100T features include:

• 15,850 logic slices, each with four 6-input LUTs and 8 flip-flops
• 4,860 Kbits of fast block RAM
• Six clock management tiles, each with phase-locked loop (PLL)
• 240 DSP slices
• Internal clock speeds exceeding 450MHz
• On-chip analog-to-digital converter (XADC)

The Nexys4 also offers an improved collection of ports and peripherals, including:

• 16 user switches
• USB-UART Bridge
• 12-bit VGA output
• 3-axis accelerometer
• 16Mbyte CellularRAM
• Pmod for XADC signals
• 16 user LEDs
• Two tri-color LEDs
• PWM audio output
• Temperature sensor
• Serial Flash
• Digilent USB-JTAG port for FPGA programming and communication
• Two 4-digit 7-segment displays
• Micro SD card connector
• PDM microphone
• 10/100 Ethernet PHY
• Four Pmod ports
• USB HID Host for mice, keyboards and memory sticks

The Nexys4 is compatible with Xilinx’s new high-performance Vivado ® Design Suite as well as the ISE toolset, which includes ChipScope and EDK. Xilinx offers free “Webpack” versions of these toolsets, so designs can be implemented at no additional cost.

Figure 1. Nexys4 board features

A growing collection of board support IP, reference designs, and add-on boards are available on the Digilent website. See the Nexys4 page at www.digilentinc.com for more information.

The Nexys4 board can receive power from the Digilent USB-JTAG port (J6) or from an external power supply. Jumper JP3 (near the power jack) determines which source is used.

All Nexys4 power supplies can be turned on and off by a single logic-level power switch (SW16). A power-good LED (LD22), driven by the “power good” output of the ADP2118 supply, indicates that the supplies are turned on and operating normally. An overview of the Nexys4 power circuit is shown below:

The USB port can deliver enough power for the vast majority of designs. A few demanding applications, including any that drive multiple peripheral boards, might require more power than the USB port can provide. Also, some applications may need to run without being connected to a PC’s USB port. In these instances an external power supply or battery pack can be used.

An external power supply can be used by plugging into to the power jack (JP3) and setting jumper J13 to “wall”. The supply must use a coax, center-positive 2.1mm internal-diameter plug, and deliver 4.5VDC to 5.5VDC and at least 1A of current (i.e., at least 5W of power). Many suitable supplies can be purchased through Digikey or other catalog vendors.

An external battery pack can be used by connecting the battery’s positive terminal to the center pin of JP3 and the negative terminal to the pin labeled J12 directly below JP3. Since the main regulator on the Nexys4 cannot accommodate input voltages over 5.5VDC, an external battery pack must be limited to 5.5VDC. The minimum voltage of the battery pack depends on the application -if the USB Host function (J5) is used, at least 4.6V needs to be provided. In other cases the minimum voltage is 3.6V.

Voltage regulator circuits from Analog Devices create the required 3.3V, 1.8V, and 1.0V supplies from the main power input. Table 2 provides additional information (typical currents depend strongly on FPGA configuration and the values provided are typical of medium size/speed designs).