The Basys 2 board is a circuit design and implementation platform that anyone can use to gain experience building real digital circuits. Built around a Xilinx Spartan-3E Field Programmable Gate Array and a Atmel AT90USB2 USB controller, the Basys 2 board provides complete, ready-to-use hardware suitable for hosting circuits ranging from basic logic devices to complex controllers.A large collection of on-board I/O devices and all required FPGA support circuits are included, so countless designs can be created without the need for any other components.
BASYS2 Development Board Features
- 100,000-gate Xilinx Spartan 3E FPGA
- Atmel AT90USB2 Full-speed USB2 port providing board power and programming/data transfer interface
- Xilinx Platform Flash ROM to store FPGA configurations
- 8 LEDs, 4-digit 7-segment display, 4 buttons, 8 slide switches
- PS/2 port and 8-bit VGA port
- User-settable clock (25/50/100MHz), plus socket for 2nd clock
- Four 6-pin header expansion connectors
- ESD and short-circuit protection on all I/O signals
BASYS2 Power Board
The Basys 2 board is typically powered from a USB cable, but a battery connector is also provided so that external supplies can be used.
To use USB power, simply attach the USB cable. To power the Basys 2 using a battery or other external source, attach a 3.5V-5.5V battery pack to the 2-pin, 100-mil spaced battery connector. Voltages higher than 5.5V on either power connector may cause permanent damage.
BASYS2 Programming Circuit
To program the Basys 2 board, set the mode jumper to PC and attach the USB cable to the board. Start the Adept software, and wait for the FPGA and the Platform Flash ROM to be recognized. Use the browse function to associate the desired .bit file with the FPGA, and/or the desired .mcs file with the Platform Flash ROM. Right-click on the device to be programmed, and select the “program” function. The configuration file will be sent to the FPGA or Platform Flash, and the software will indicate whether programming was successful. The “Status LED” LED (LD_8) will also blink after the FPGA has been successfully configured. For further information on using Adept, please see the Adept documentation available at the Digilent website.
BASYS2 Oscillator Circuit
The Basys 2 board includes a primary, user-settable silicon oscillator that produces 25MHz, 50MHz, or 100MHz based on the position of the clock select jumper at JP4.
BASYS2 User Input/Output Circuit
Four pushbuttons and eight slide switches are provided for circuit inputs. Pushbutton inputs are normally low and driven high only when the pushbutton is pressed. Slide switches generate constant high or low inputs depending on position. Pushbuttons and slide switches all have series resistors for protection against short circuits (a short circuit would occur if an FPGA pin assigned to a pushbutton or slide switch was inadvertently defined as an output).
Eight LEDs and a four-digit seven-segment LED display are provided for circuit outputs. LED anodes are driven from the FPGA via current-limiting resistors.
The 7-Segment display is common anode is driven via FPGA.
BASYS2 PS/2 Circuit
The 6-pin mini-DIN connector can accommodate a PS/2 mouse or keyboard. The PS/2 connector is supplied with 5VDC.
Both the mouse and keyboard use a two-wire serial bus (clock and data) to communicate with a host device. Both use 11-bit words that include a start, stop and odd parity bit, but the data packets are organized differently, and the keyboard interface allows bi-directional data transfers (so the host device can illuminate state LEDs on the keyboard). Bus timings are shown in the figure.
BASYS2 VGA Port Circuit
The Basys 2 board uses 10 FPGA signals to create a VGA port with 8-bit color and the two standard sync signals (HS – Horizontal Sync, and VS – Vertical Sync).
BASYS2 Expansion Connectors
The Basys 2 board provides four 6-pin peripheral module connectors. Each connector provides Vdd, GND, and four unique FPGA signals. Several 6-pin module boards that can attach to this connector are available from Digilent, including A/D converters, speaker amplifiers, microphones, H-bridge amplifiers, etc. Please see www.digilentinc.com for more information.
BASYS2 FPGA Board Pin Definitions
The table below shows all pin definitions for the Spartan-3E on the Basys 2 board. Pins in grey boxes are not available to the user.
You can reach the BASYS2 FPGA board of schematic drawings and technical documents.