Digilent 410-044-10P-KIT - Manual (Page 15)

Spartan-3 Starter Kit Board User Guide www.xilinx.com 15
UG130 (v1.1) May 13, 2005 1-800-255-7778
R
Chapter 3
Four-Digit, Seven-Segment LED Display
The Spartan-3 Starter Kit board has a four-character, seven segment LED display
controlled by FPGA user-I/O pins, as shown in
Figure 3-1 . Each digit shares eight common
control signals to light individual LED segments. Each individual character has a separate
anode control input. A detailed schematic for the display appears in
Figure A-2 .
The pin number for each FPGA pin connected to the LED display appears in parentheses.
To light an individual signal, drive the individual segment control signal Low along with
the associated anode control signal for the individual character. In
Figure 3-1 , for example,
the left-most character displays the value ‘2’. The digital values driving the display in this
example are shown in blue. The AN3 anode control signal is Low, enabling the control
inputs for the left-most character. The segment control inputs, A through G and DP, drive
the individual segments that comprise the character. A Low value lights the individual
segment, a High turns off the segment. A Low on the A input signal, lights segment ‘a’ of
the display. The anode controls for the remaining characters, AN[2:0] are all High, and
these characters ignore the values presented on A through G and DP.
Table 3-1 lists the FPGA connections that drive the individual LEDs comprising a seven-
segment character. Table 3-2 lists the connections to enable a specific character. Table 3-3
shows the patterns required to display hexadecimal characters.
Figure 3-1: Seven-Segment LED Digit Control
A
B
C
D
E
F
G
DP
f
a
b
e c
g
d
(E14)
(G13)
(N15)
(P15)
(R16)
(F13)
(N16)
(P16)
f
a
b
e c
g
d
f
a
b
e c
g
d
f
a
b
e c
g
d
AN3 (E13) AN2 (F14) AN1 (G14) AN0 (D14)
0
0
0
1
0
0
1
0
1
1 1 1
UG130_c3_01_042704
dp dp dp dp