Digilent Nexys Board - Manual (Page 5)

Digilent
Nexys Reference Manual
www.digilentinc.com
Copyright Digilent, Inc. Page 5/10 Doc: 502-107
Spartan 3
FPGA
K13
K14
J13
K16
K15
L15
M16
M15
K12
N16
BTN0
BTN1
BTN2
BTN3
SW0
SW1
SW2
SW3
SW4
SW5
SW6
SW7
3.3V
LD0
LD1
LD2
LD3
LD4
LD5
LD6
LD7
3.3V
LEDs
AN0
AN1
AN2
AN3
J16
N15
L14
L13
M14
L12
N14
M13
P14
R16
G14
G12
G13
F12
F13
E13
G15
H13
J14
E14
G16
CA
CB
CC
CD
CE
CF
CG
DP
H14
Slide
Switches
3.3V
Buttons
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).
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 Nexys 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
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.