EE543 Introduction to Digital Systems
LABORATORY #5
Combinational Logic Design
OBJECTIVE:
The objective of this laboratory is to design, build, and then test a combinational logic circuit.
EQUIPMENT REQUIRED:
Global Specialties Design and Prototyping PB-505
Wire Leads
1 Logic Probe
1 seven-segment LED display
2 7400 TTL NAND Integrated Circuit (IC) chips
3 7410 TTL Triple 3-input NAND IC chips
1 7404 TTL Hex Inverter IC chip
PROCEDURE:
PRELAB
Design a circuit which will convert a 3-bit binary input (S2, S1, S0) to an octal digit on a 7-segment LED
display. You will have available the 7400 series TTL IC chips from the equipment list above, as well as a
7-segment LED display. You will arrange the IC’s on the PB-505 in the following order with the first 4 in a
horizontal row on the top of the board and the last 3 just below in another horizontal row. Keep the
placement of the chips in mind as you layout how you will wire the circuit so that, for example, a 2-input
NAND connected to a 3-input NAND will go from chips 2 to 3 instead of 6 to 4 as the latter makes the design
more complicated:
Chip #
Chip Model #
Chip #
Chip Model #
1
2
3
4
7404
7400
7410
7410
5
6
7
7410
7400
7-seg. Disp.
Come to lab with the correct truth-table, K-maps, simplified Boolean functions, DeMorgan's theorem derived
NAND equations, circuit diagram, and wiring list. You will have 7 K-maps and 7 Boolean functions when
complete. On the truth-table that you generate it is advantageous for you to have all of the intermediate gate
outputs in addition to the outputs to the LED, in this way you can trouble-shoot more easily, though this is not
required. In your design, let segment 'a' = 0 when S2/S1/S0 = 1/1/0.
LAB
Assemble and test your circuit. Demonstrate that it works correctly to the satisfaction of your instructor.
Make sure that you include in the Lab report what happened in ALL of the possible 8 input cases (i.e., what
did the output look like, show which LED segments lit up for each case). How do your lab results compare
with the results you predicted in prelab?
THE SEVEN SEGMENT LED DISPLAY
The 7 LEDs have a common anode at pin 14. This is connected to +5 volts through a 47 ohm resistor (to
limit current). The LEDs are activated (turned on) by the application of zero volts (i.e., Logic zero) to one of
the inputs 'a' through 'g' which are connected to the cathodes of the LEDs (see the attached sheet for the pin
connections of the LED seven-segment display).
Last Update: 1/21/2013
EE543 Introduction to Digital Systems
a
f
b
g
e
c
d
LED Diagram
Pin# - Connection
01 - Cathode 'a'
02 - Cathode 'f'
03 - Common-Anode
04 - NO PIN
05 - NO PIN
06 - Cathode 'Decimal Point'
07 - Cathode 'e'
08 - Cathode 'd'
09 - No Internal Connection
10 - Cathode 'c'
11 - Cathode 'g'
12 - NO PIN
13 - Cathode 'b'
14 - Common-Anode
Last Update: 1/21/2013