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Revision: August 8, 2006 215 E Main Suite D | Pullman, WA 99163
www.digilentinc.com
(509) 334 6306 Voice and Fax
Overview
Digilent’s Basys circuit board is an integrated
circuit development platform based on a Xilinx
Spartan 3E Field Programmable Gate Array
(FPGA). The Basys board provides a lowcost, introductory development platform for
engineers to try new designs or learn about
FPGAs and modern CAD tools. Basys
features include:
• 100,000 gate Xilinx Spartan 3E FPGA;
• JTAG programming port;
• XCF02S Xilinx Platform Flash ROM to
store FPGA configurations;
• Large collection of I/O devices including
eight LEDs, four-digit seven-segment
display, four pushbuttons, and eight slide
switches;
• PS/2 and VGA ports;
• User-selectable oscillator
Power
jack
5-12VDC
3.3VDC
regulator
2.5VDC
regulator
1.2VDC
regulator
Clock
(100,
50, or
25
MHz)
Platform
Flash
(config
ROM)
JTAG
6-pin connectors
For A/D & D/A converters,
motor drivers, etc.
JA
JB JC
4 4 4 4
JD
(25/50/100MHz), plus a socket for a
second oscillator;
• Four 6-pin header ports for user I/O and
Featuring 4 18-bit multipliers and 9Kbytes of Block RAM
Xilinx Spartan3E-100 TQ100
peripheral module connection;
• ESD and short-circuit protection on all I/O
signals.
Functional Description
The Basys board provides an inexpensive,
robust, and easy-to-use platform that anyone
8 LEDs
4 7-seg.
displays
Figure 1: Basys block diagram
4 buttons
8 switches
PS2
Port
VGA Port
can use to gain experience with FPGA devices
and modern design methods. It is centered on
the Spartan 3E FPGA, and it contains all needed support circuits so designs can get up and running
quickly. The large collection of on-board I/O devices allow many designs to be completed without the
need for any other hardware, making the Basys an ideal introductory platform for experimenting with
new designs or learning about FPGAs and CAD tools. The four standard 6-pin expansion connectors
allow designs to grow beyond the Basys board, either with user-designed boards or breadboards
and/or peripheral module (Pmod) boards offered by Digilent. (Pmods are inexpensive analog and
digital I/O modules that offer A/D conversion, D/A conversion, motor drive, sensor input, and a host of
other features). Signals on each 6-pin expansion connector are protected against damage from ESD
and short-circuit connections, ensuring a long operating life in any environment. The Basys board
works seamlessly with all versions of the Xilinx ISE tools, including the free WebPack tools. It ships
with a power supply and programming cable, so designs can be implemented immediately without the
need for any additional hardware.
®
Copyright Digilent, Inc. All rights reserved 12 pages Doc: 502-107
Basys Reference Manual
Digilent
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Device Configuration
At power-on, the FPGA on the Basys board is not configured and performs no functions - it must be
configured (or programmed) by the user before it can perform any functions. Design software, like the
free WebPack from Xilinx, can be used to define any number of circuits that can be programmed into
the FPGA. Once programmed, the FPGA will retain its configuration only as long is power is applied.
The FPGA can be programmed in two ways: directly from a PC, and from an on-board Platform Flash
ROM that is also user-programmable. A jumper on the Basys board determines which source (PC or
ROM) the FPGA will use to load its configuration. Note that a demonstration configuration is loaded
into the Basys board during manufacturing. If that configuration has not been overwritten, it can be
automatically loaded into the FPGA by setting the Mode Select Jumper to “ROM”, and cycling power
or pressing the reset button (labeled “BTN_R”).
The FPGA and the Platform Flash ROM can be programmed from a PC using Digilent’s Adept
software or Xilinx’s iMPACT software (both are available for free download). Digilent’s JTAG3 cable
can be used to connect the board to a PC for programming with either software package.
To program the Basys board, connect the programming cable to the board
and to a PC, and apply power to the Basys board. Start the programming
software, and wait for the FPGA and the Platform Flash ROM to be
automatically identified. To program the FPGA, select the desired .bit file; to
program the Platform Flash, select the desired .mcs file. 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.
Both the FPGA and Platform Flash ROM will always appear in the scan chain. After the Platform
Flash ROM has been loaded with a configuration file, the FPGA can automatically load that file at
power-on if programming mode control jumper is loaded in the ROM position.
A reset button is provided (labeled “BTN_R”) that can erase the configuration in the FPGA, and start a
new programming cycle. An LED labeled “LD_D” will illuminate whenever the FPGA has been
successfully configured.
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Digilent
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Power Supply
The Basys board can be powered from any DC supply that produces a voltage in the 5VDC-12VDC
range. The power jack on the Basys board requires a center-positive, 2.1mm power supply connector
as is commonly found on wall-plug power supplies (Basys ships with a 5VDC wall-plug supply).
Voltages higher than 12V may permanently damage Basys.
The voltage input to the power jack is routed to the four 6-pin expansion connectors and to a LM1117
voltage regulator that produces the 3.3V supply for the board. The 2.5V and 1.2V supplies required by
the FPGA are produced by post-regulating the 3.3V supply. Total board current is dependant on
FPGA configuration, clock frequency, and external connections. In test circuits with roughly 20K gates
routed, a 50MHz clock source, and all LEDs illuminated, about 200mA of current is drawn from the
1.2V supply, 50mA from the 2.5V supply, and 100mA from the 3.3V supply. Required current will
increase if larger circuits are configured in the FPGA, and if peripheral boards are attached.
The Basys board uses a four layer PCB, with the inner layers dedicated to VCC and GND planes. The
FPGA and the other ICs on the board all have a large complement of bypass capacitors placed as
close as possible to each VCC pin. The power supply routing and bypass capacitors result in a very
clean, low-noise power supply.
Oscillators
The Basys board includes a primary, usersettable silicon oscillator that produces 25MHz,
50MHz, or 100MHz based on the position of the
clock select jumper at JP3. A socket for a second
oscillator is also provided at IC7 (the IC7 socket
can accommodate any 3.3V CMOS oscillator in a
half-size DIP package). The primary and
secondary oscillators are connected to global
clock input pins at pin 36 and pin 84 respectively.
Both clock inputs can drive the clock synthesizer
DLL on the Spartan 3E, allowing for a wide range
if internal frequencies, from 4 times the input
frequency to any integer divisor of the input
frequency.
User I/O
The Basys board includes several Input and Output devices, and several data ports so that many
designs can be implemented without the need for any other components.
Inputs: Slide Switches and Pushbuttons
Four pushbuttons and eight slide switches are provided for circuit inputs. Pushbutton inputs are
normally low, and they are driven high only when the pushbutton is pressed. Slide switches generate
constant high or low inputs depending on their position. Pushbutton and slide switch inputs use a
series resistor 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).
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Digilent
www.digilentinc.com
3.3V
Slide
switches
BTN0
BTN1
BTN2
BTN3
3.3V
SW0
SW1
SW2
SW3
SW4
SW5
SW6
SW7
69
30
13
11
98
95
94
92
91
90
89
88
Spartan 3E
FPGA
15
12
10
33
32
27
26
42
24
22
17
16
43
23
18
LD0
LD1
LD2
LD3
9
LD4
5
LD5
4
LD6
3
LD7
2
AN1
AN2
CA
CB
CC
CD
CE
CF
CG
DP
LEDs
3.3V
AN3
AN4
Sseg
Display
Outputs: LEDs
Eight LEDs are provided for circuit outputs. LED anodes are driven from the FPGA via 390-ohm
resistors, so a logic ‘1’ output will illuminate them with 3-4ma of drive current. A ninth LED is provided
as a power-on LED, and a tenth LED indicates FPGA programming status.
Outputs: Seven-Segment Display
The Basys board contains a four-digit common anode seven-segment LED display. Each of the four
digits is composed of seven segments arranged in a “figure 8” pattern, with an LED embedded in
each segment. Segment LEDs can be individually illuminated, so any one of 128 patterns can be
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Digilent
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displayed on a digit by illuminating certain LED segments and leaving the others dark. Of these 128
possible patterns, the ten corresponding to the decimal digits are the most useful.
The anodes of the seven LEDs forming
each digit are tied together into one
Common anode
“common anode” circuit node, but the LED
cathodes remain separate. The common
anode signals are available as four “digit
AN1 AN2 AN3 AN4
F
A
B
enable” input signals to the 4-digit display.
The cathodes of similar segments on all four
displays are connected into seven circuit
nodes labeled CA through CG (so, for
example, the four “D” cathodes from the
four digits are grouped together into a single
circuit node called “CD”). These seven
cathode signals are available as inputs to
CA CB CC CD CE CF CG DP
E
Four-digit Seven
Segment Display
Individual cathodes
G
D
C
DP
the 4-digit display. This signal connection
scheme creates a multiplexed display, where the
cathode signals are common to all digits but they
can only illuminate the segments of the digit whose
corresponding anode signal is asserted.
A scanning display controller circuit can be used to
show a four-digit number on this display. This
circuit drives the anode signals and corresponding
cathode patterns of each digit in a repeating,
continuous succession, at an update rate that is
faster than the human eye can respond. Each digit
is illuminated just one-quarter of the time, but
because the eye cannot perceive the darkening of
a digit before it is illuminated again, the digit appears continuously illuminated. If the update or
“refresh” rate is slowed to a given point (around 45 hertz), then most people will begin to see the
display flicker.
In order for each of the four digits to
appear bright and continuously
illuminated, all four digits should be driven
once every 1 to 16ms (for a refresh
frequency of 1KHz to 60Hz). For example,
in a 60Hz refresh scheme, the entire
display would be refreshed once every
16ms, and each digit would be illuminated
for ¼ of the refresh cycle, or 4ms. The
controller must assure that the correct
cathode pattern is present when the
corresponding anode signal is driven. To
illustrate the process, if AN1 is asserted
while CB and CC are asserted, then a “1” will be displayed in digit position 1. Then, if AN2 is asserted
while CA, CB and CC are asserted, then a “7” will be displayed in digit position 2. If A1 and CB, CC
are driven for 4ms, and then A2 and CA, CB, CC are driven for 4ms in an endless succession, the
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Digilent
www.digilentinc.com
display will show “17” in the first two digits. An example timing diagram for a four-digit controller is
provided.
Ports and External Connectors
PS/2 Port
The Basys board includes a 6-pin mini-DIN connector
that can accommodate a PS/2 mouse or keyboard
connection. Most PS/2 devices can operate from a
3.3V supply, but some devices, like older keyboards,
require a 5VDC supply. A jumper on the Basys board
(JP1) can be used to select whether 3.3V or VU is
supplied to the PS/2 Vdd pin. If 5V is required, set JP1
to VU and ensure that Basys is powered with a 5VDC
wall-plug supply (note that Basys ships with a 5VDC
wall-plug supply).
PS/2 connector pin locations, pin assignments, and jumper settings
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. The clock and
data signals are only driven when data transfers occur, and otherwise they are held in the “idle” state
at logic ‘1’. The timings define signal requirements for mouse-to-host communications and bidirectional keyboard communications.
Edge 0
T
T
CK
CK
Edge 10
Keyboard
The keyboard uses open-collector drivers so that either
the keyboard or an attached host device can drive the
two-wire bus (if the host device will not send data to the
keyboard, then the host can use input-only ports).
CLK
DATA
T
T
SU
HLD
PS2-style keyboards use scan codes to communicate
key press data (nearly all keyboards in use today are
PS2 style). Each key has a single, unique scan code
that is sent whenever the corresponding key is
pressed. If the key is pressed and held, the scan code
will be sent repeatedly about once every 100ms. When
a key is released, a “F0” key-up code is sent, followed
Symbol Parameter Min Max
T
Clock time
CK
T
Data-to-clock setup time
SU
T
Clock-to-data hold time 5us 25us
HLD
'1' stop bit'0' start bit
30us
5us
50us
25us
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Digilent
www.digilentinc.com
by the scan code of the released key. If a key can be “shifted” to produce a new character (like a
capital letter), then a shift character is sent in addition to the original scan code, and the host device
must determine which character to use. Some keys, called extended keys, send an “E0” ahead of the
scan code (and they may send more than one scan code). When an extended key is released, an “E0
F0” key-up code is sent, followed by the scan code. Scan codes for most keys are shown in the figure
below.
A host device can also send data to the keyboard. Below is a short list of some often-used
commands.
ED Set Num Lock, Caps Lock, and Scroll Lock LEDs. After receiving an “ED”, the keyboard returns an “FA”;
then the host sends a byte to set LED status: Bit 0 sets Scroll Lock; bit 1 sets Num Lock; and Bit 2 sets
Caps lock. Bits 3 to 7 are ignored.
EE Echo. Upon receiving an echo command, the keyboard replies wit h “EE”.
F3 Set scan code repeat rate. The keyboard acknowledges receipt of an “F3” by returning an “FA”, after
which the host sends a second byte to set the repeat rate.
FE Resend. Upon receiving FE, the keyboard re-sends the last scan code sent.
FF Reset. Resets the keyboard.
ESC
76
` ~
0E
TAB
0D
Caps Lock
58
Shift
12
Ctrl
14
F105F206F304F4
0C
1 !162 @1E3 #264 $255 %
2E
Q
15W1DE24R2DT2C
A
1CS1BD23F2BG34
Z
1ZX22C21V2AB32
Alt
11
F503F60BF783F8
0A
6 ^367 &3D8 *3E9 (460 )45- _4E= +55BackSpace
Y
35U3CI43
H
33J3BK42L4B
N
31M3A
Space
29
O
44P4D
, <41> .
F901F1009F1178F12
49
[ {
54
; :
4C
/ ?
4A
Alt
E0 11
] }
5B
' "
52
07
66
\ |
5D
Enter
5A
Shift
59
Ctrl
E0 14
E0 75
E0 74
E0 6B
E0 72
The keyboard should send data to the host only when both the data and clock lines are high (or idle).
Since the host is the “bus master”, the keyboard should check to see whether the host is sending data
before driving the bus. To facilitate this, the clock line can be used as a “clear to send” signal. If the
host pulls the clock line low, the keyboard must not send any data until the clock is released (host-tokeyboard data transmission will not be dealt with further here).
The keyboard sends data to the host in 11-bit words that contain a ‘0’ start bit, followed by 8-bits of
scan code (LSB first), followed by an odd parity bit and terminated with a ‘1’ stop bit. The keyboard
generates 11 clock transitions (at around 20 - 30KHz) when the data is sent, and data is valid on the
falling edge of the clock.
Mouse
The mouse outputs a clock and data signal when it is moved; otherwise, these signals remain at logic
‘1’. Each time the mouse is moved, three 11-bit words are sent from the mouse to the host device.
Each of the 11-bit words contains a ‘0’ start bit, followed by 8 bits of data (LSB first), followed by an
odd parity bit, and terminated with a ‘1’ stop bit. Thus, each data transmission contains 33 bits, where
Copyright Digilent, Inc. Page 7/12 Doc: 502-107
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Digilent
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bits 0, 11, and 22 are ‘0’ start bits, and bits 11, 21, and 33 are ‘1’ stop bits. The three 8-bit data fields
contain movement data as shown below. Data is valid at the falling edge of the clock, and the clock
period is 20 to 30KHz.
The mouse assumes a relative coordinate system wherein moving the mouse to the right generates a
positive number in the X field, and moving to the left generates a negative number. Likewise, moving
the mouse up generates a positive number in the Y field, and moving down represents a negative
number (the XS and YS bits in the status byte are the sign bits – a ‘1’ indicates a negative number).
The magnitude of the X and Y numbers represent the rate of mouse movement – the larger the
number, the faster the mouse is moving (the XV and YV bits in the status byte are movement overflow
indicators – a ‘1’ means overflow has occurred). If the mouse moves continuously, the 33-bit
transmissions are repeated every 50ms or so. The L and R fields in the status byte indicate Left and
Right button presses (a ‘1’ indicates the button is being pressed).
Mouse status byte X direction byte Y direction byte
L R 0 1 XS YS XY YY P X0 X1 X2 X3 X4 X5 X6 X7 P Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 P10 100 11
Idle state
Start bit Stop bit
Start bit
VGA Port
The five standard VGA signals Red, Green, Blue,
Horizontal Sync (HS), and Vertical Sync (VS) are
routed directly from the FPGA to the VGA connector,
resulting in a simple video system that can produce
eight colors. The color signals from the FPGA include
270-ohm series resistors that form a divider with the
75-ohm termination resistance of the VGA display.
This simple circuit ensures that the video signals
cannot exceed the VGA-specified maximum voltage,
and results in color signals that are either fully on
(.7V) or fully off (0V).
Stop bit
Spartan 3E
FPGA
Start bit
49
47
48
41
40
Basys VGA Circuit Diagram
270
270
270
200
200
Stop bit
Idle state
RED
GRN
BLU
HS
VS
VGA signal timings are specified, published, copyrighted and sold by the VESA organization
(www.vesa.org). The following VGA system timing information is provided as an example of how a
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Digilent
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VGA monitor might be driven in 640 by 480 mode. For more precise information, or for information on
higher VGA frequencies, refer to documentation available at the VESA website.
VGA System Timing
CRT-based VGA displays use amplitude-modulated moving electron beams (or cathode rays) to
display information on a phosphor-coated screen. LCD displays use an array of switches that can
impose a voltage across a small amount of liquid crystal, thereby changing light permittivity through
the crystal on a pixel-by-pixel basis. Although the following description is limited to CRT displays, LCD
displays have evolved to use the same signal timings as CRT displays (so the “signals” discussion
below pertains to both CRTs and LCDs). Color CRT displays use three electron beams (one for red,
one for blue, and one for green) to energize the phosphor that coats the inner side of the display end
of a cathode ray tube (see illustration). Electron beams emanate from “electron guns”, which are
finely-pointed heated cathodes placed in close proximity to a positively charged annular plate called a
“grid”. The electrostatic force imposed by the grid pulls rays of energized electrons from the cathodes,
and those rays are fed by the current that flows into the cathodes. These particle rays are initially
accelerated towards the grid, but they soon fall under the influence of the much larger electrostatic
force that results from the entire phosphor-coated display surface of the CRT being charged to 20kV
(or more). The rays are focused to a fine beam as they pass through the center of the grids, and then
they accelerate to impact on the phosphor-coated display surface. The phosphor surface glows
brightly at the impact point, and it continues to glow for several hundred microseconds after the beam
is removed. The larger the current fed into the cathode, the brighter the phosphor will glow.
Anode (entire screen)
Cathode ray tube
Deflection coils
Grid
Cathode ray
Cathode Ray Tube
Display System
Electron guns
(Red, Blue, Green)
R,G,B signals (to guns)
VGA cable
High voltage
supply (>20kV)
deflection
control
grid
control
gun
control
Sync signals
(to deflection control)
Between the grid and the display surface, the beam passes through the neck of the CRT where two
coils of wire produce orthogonal electromagnetic fields. Because cathode rays are composed of
charged particles (electrons), they can be deflected by these magnetic fields. Current waveforms are
passed through the coils to produce magnetic fields that interact with the cathode rays and cause
them to transverse the display surface in a “raster” pattern, horizontally from left to right and vertically
from top to bottom. As the cathode ray moves over the surface of the display, the current sent to the
electron guns can be increased or decreased to change the brightness of the display at the cathode
ray impact point.
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Information is only displayed when the beam is moving in the “forward” direction (left to right and top
to bottom), and not during the time the beam is reset back to the left or top edge of the display. Much
of the potential display time is therefore lost in “blanking” periods when the beam is reset and
stabilized to begin a new horizontal or vertical display pass. The size of the beams, the frequency at
which the beam can be traced across the display, and the frequency at which the electron beam can
be modulated determine the display resolution. Modern VGA displays can accommodate different
resolutions, and a VGA controller circuit dictates the resolution by producing timing signals to control
the raster patterns. The controller must produce synchronizing pulses at 3.3V (or 5V) to set the
frequency at which current flows through the deflection coils, and it must ensure that video data is
applied to the electron guns at the correct time. Raster video displays define a number of “rows” that
corresponds to the number of horizontal passes the cathode makes over the display area, and a
number of “columns” that corresponds to an area on each row that is assigned to one “picture
element” or pixel. Typical displays use from 240 to 1200 rows and from 320 to 1600 columns. The
overall size of a display and the number of rows and columns determines the size of each pixel.
Video data typically comes from a video refresh memory, with one or more bytes assigned to each
pixel location (the Basys uses three bits per pixel). The controller must index into video memory as
the beams move across the display, and retrieve and apply video data to the display at precisely the
time the electron beam is moving across a given pixel.
A VGA controller circuit must generate the HS and VS timings signals and coordinate the delivery of
video data based on the pixel clock. The pixel clock defines the time available to display one pixel of
information. The VS signal defines the “refresh” frequency of the display, or the frequency at which all
information on the display is
redrawn. The minimum
refresh frequency is a
pixel 0,0
pixel 0,639
function of the display’s
phosphor and electron beam
intensity, with practical
refresh frequencies falling in
the 50Hz to 120Hz range.
The number of lines to be
displayed at a given refresh
frequency defines the
horizontal “retrace”
frequency. For a 640-pixel by
480-row display using a
25MHz pixel clock and 60 +/1Hz refresh, the signal
timings shown in the table
Current
through
horizontal
defletion
coil
640 pixels are displayed each
time the beam travels across
the screen
VGA display
surface
pixel 479,0 pixel 479,639
Stable current ramp - information
displayed during this time
Retrace - no
information
displayed
during this
time
below can be derived.
Timings for sync pulse width
and front and back porch
intervals (porch intervals are
the pre- and post-sync pulse
times during which
time
Horizontal display time
Total horizontal time
retrace
time
information cannot be
displayed) are based on
observations taken from
actual VGA displays.
HS
Horizontal sync signal
sets retrace frequency
"back porch""front porch"
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A VGA controller circuit decodes the output of a horizontal-sync counter driven by the pixel clock to
generate HS signal timings. This counter can be used to locate any pixel location on a given row.
Likewise, the output of a vertical-sync counter that increments with each HS pulse can be used to
generate VS signal timings, and this counter can be used to locate any given row. These two
continually running counters can be used to form an address into video RAM. No time relationship
between the onset of the HS pulse and the onset of the VS pulse is specified, so the designer can
arrange the counters to easily form video RAM addresses, or to minimize decoding logic for sync
pulse generation.
Symbol Parameter
T
Sync pulse time
S
T
Display time
disp
T
VS pulse width
pw
T
VS front porch
fp
T
VS back porch
bp
Vertical Sync
Time Clocks Lines
16.7ms
15.36ms
320 us
928 us
64 us
416,800
384,000
1,600
8,000
23,200
Horizontal Sync
Time
521
480
25.6 us
2
3.84 us
10
640 ns
29
1.92 us
32 us
Clocks
800
640
96
16
48
T
S
T
disp
T
pw
T
fp
T
bp
VGA controller signal timings and circuit block diagram
6-pin header connectors
The Basys 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
speaker boards, H-bridge boards, sensor boards, etc. Please see
www.digilentinc.com for more
information.
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79
78
71
70
Spartan 3E
FPGA
Resistors for short-
circuit protection
ESD protection
diodes
1
2
3
4
5
6
supply
jumper
6-pin
header
JA
Power
JPA
VU
3.3V
Digilent
www.digilentinc.com
68
67
66
65
63
62
61
60
58
57
54
53
1
2
3
4
1
2
3
4
1
2
3
4
6-pin
header
JB
6-pin
header
JC
6-pin
header
JD
6-pin header connector circuit diagram. ESD diodes
and power jumper shown for JA are present for the
other connectors but omitted from the drawing.
FPGA
The pinout for the Spartan 3E-100 FPGA in the VQ100 package is shown in the table below.
Pin Function Pin Function Pin Function Pin Function Pin Function
1
PROG_B
21
2 LD7 22 CC 42 MODE1/C 62 JC-2 82
3
LD6 23 CG 43 MODE0/C 63 JC-1 83 SPI-SS
4 LD5 24 CB 44
5 LD4 25
6
7
8
V
INT
GND
3V3
26 AN4 46
27 AN3 47 VGA-G 67 JB-2 87
28
9 LD3 29
10 LD2 30 BTN1 50
11 BTN3 31
12 LD1 32 AN2 52
13 BTN2 33 AN1 53 JD-4 73
14
GND
34 SPI-MOSI 54 JD-3 74
15 LD0 35 SPI-MISO 55
16 CE 36 CLK1 56
17 CD 37
18 DP 38 SPI-SCK 58 JD-1 78 JA2 98 SW0
19
20
GND
3V3
39
40 VGA-VS 60 JC-4 80
Basys FPGA Pin Assignments
V
AUX
3V3
V
INT
GND
3V3
GND
MODE2
41 VGA-HS 61 JC-3 81
D0
45
3V3
V
AUX
48 VGA-B 68 JB-1 88 SW7
49 VGA-R 69 BTN0 89 SW6
CCLK
51
V
AUX
GND
3V3
V
INT
57 JD-2 77
59
GND
GND
3V3
64
GND
84 CLK2
65 JB-4 85 PS2C
66 JB-3 86 PS2D
GND
70 JA-4 90 SW5
71 JA-3 91 SW4
72
GND
3V3
V
AUX
75
TMS
76
TDO
TCK
79 JA1 99
V
INT
92 SW3
93
GND
94 SW2
95 SW1
96
V
AUX
97
3V3
TMS-EN
100
TDI
Copyright Digilent, Inc. Page 12/12 Doc: 502-107
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