UNIVERSITY OF NORTH CAROLINA AT CHARLOTTE
Department of Electrical and Computer Engineering
Experiment No. 2 - BCD to Seven Segment display
Overview:
A seven-segment decoder is a logic circuit often used for the visual display of digital
data. The seven outputs of the decoder will drive the seven segments on a corresponding
display. BCD is the acronym for Binary Coded Decimal. The BCD system is used to
represent the decimal numbers from 0 to 9 in a binary format suitable for digital devices.
A four-bit code is required with the decimal characters 0 through 9 represented by the
binary numbers 0000 through 1001. The combinations 1010 through 1111 are not used. A
BCD to seven-segment decoder driver will allow the display of a binary coded decimal
on a seven-segment display. The input to the decoder is a number from 0 through 9 in
BCD and the output provides the seven inputs required to drive the seven-segment
display. The following steps will be implemented: 1) truth tables will be constructed, 2)
K-maps will be used to reduce the logic and 3) the gate level logic design will be created
for a BCD to a seven-segment decoder.
The Objective:
To design, build and provide hands-on experience with BCD to seven segment display.
Suggested equipment list:
Qty
1
1
1
1
8
8
2
1
1
Description
74LS47,74LS163
5V power supply
Oscilloscope with probe
Voltmeter
2.4K resistor 1/4W
LED
10k resistor 1/4W
Signal generator
7 segment display
Pre-Lab –Seven Segment
Step 3: For each K-map, draw the gate level circuits that the equation represents.
Note: Use AND gates and OR gates as required for implementation.
(INSTRUCTOR’S SIGNATURE_________________________DATE_____________)
Lab Session – Seven Segment
1. The chip 74LS47 is a BCD to seven segment decoder driver. The BCD inputs for the chips are
generated using the 74LS163. This output is fed to the inputs of 72LS47 chip, which in turn is
connected to the seven segment display. The connections have to be done in parts. First the
correct functioning of the counter should be check by using LED. Then the outputs of this should
be connected to that of 74LS47 and again the output of this should be verified by LED'
s. Finally
the seven segment display should be connected and the correct functioning of the whole system
should be verified.
2. Test the system to make sure that the seven segment display counts from 0-9
Figure 1: Screen Shot of design in Mentor graphic
Figure 2: Screen Shot of trace in Mentor graphics
Figure 3: Chip diagrams (Easier to follow, use this to make the connections)
Figure 4: Circuit Diagram
Data Sheet for 74LS163A 74LS47
Note: Pin 8 for 74ls47 should be connected to ground.
The outputs of 74ls47 (pins 9 through 15 should be connected to 2.4K resistor before connecting
to 7 the segment display).