7 Segment LED Display
Core Concept Instructions
Materials:
myDAQ
7 Segment LED Display
Learn It!
Displays based on seven LED
segments arranged in an “8”
pattern provide a simple means to
display numbers 0 to 9 and some
letters of the alphabet shaft. Each
of the seven line segments as well
as the decimal point is an
individual LED, each with its own
anode and cathode. To conserve
the number of electrical
connections on the display, all of
the eight are tied together and
brought out as the “common
anode” pin.
Seven-segment displays are widely
used in digital clocks, electronic
meters, and other electronic
devices for displaying numeric
information. In this exercise, you will
implement a Seven-Segment
Display circuit and create a
program to manually activate
each segment individually.
“Seven-segment
displays are widely
used in digital
clocks, electronic
meters, and other
electronic devices
for displaying
numeric
information.”
Build It!
The Seven-Segment Display receives 7 different digital signals,
one for each LED.
Creating a Seven-Segment Display Circuit
Step 1: Connect the Seven-Segment Display as indicated in the
Multisim circuit in figure 3. Observe how each of the 7 segments is wired
to a digital input/output.
Step 2: Download the myDAQ 7 Segment Display Module from the Resource
Tab. Open the myDAQ 7 Segment Display VI. The front panel should be
8 Boolean controls like in figure 1. These controls determine the state of
the segments and the decimal point.
Page 1
Seven Segment LED– Instruction Set
Step 3: Run the VI and determine which
segments need to be active for each
integer 0-9. Toggle the eight front-panel
switches to activate and deactivate
each segment a through g as well as the
decimal point.
Figure 1: Seven-Segment Display Front Panel
Step 4: Examine the code on the block
diagram of the Main VI.
The main structure of this program is a while
loop, which allows measurements to
repeatedly be taken and displayed on the
front panel. Notice how the segments are
independent of each other, and each one is
treated as a single LED.
Figure 2: Writing the digital output signals
Guiding Questions:
• Are the digital outputs to the SevenSegment Display active high or
active low?
• How would you measure the total
current flowing through the circuit
when all of the segments are active?
Page 2
Seven Segment LED– Instruction Set
Figure 3: 7 Segment Circuit
Expand It!
• Display a numerical front-panel control value as its corresponding pattern on
the seven-segment display. Display the values 0-9 and a dash for values
greater 9.
• Create a rotating chase sequence in which a single active segment appears
to move around the periphery of the display. Make the speed adjustable, and
also include a control to reverse the direction of rotation. Consider a single
Boolean array constant connected to Rotate 1D Array in the Programming !
Array subpalette.
Research It!
Study the video Seven-Segment LED Interfacing Theory (youtu.be/P0ER0VXvfSw, 4:11)
to learn about the voltage-current characteristics of the individual LED segment, why
the segment controls are active-low, and why no current-limiting resistors are
required for this particular device.
Caption describing(youtu.be/ejyOo_k9Kl0,
picture or graphic.
Study the video Seven-Segment LED Demo Walk-Through
2:03) to learn the design principles of 7-segment display.
Seven-segment LED display datasheet,
http://www.sparkfun.com/datasheets/Components/LED/YSD-160AB3C-8.pdf
Page 3
Seven Segment LED– Instruction Set