Wk2 - EECE 259 - Lab 1 - Using Multisim.pdf - Courses - University ...

Rational: The purpose of this lab is :-
University of British Columbia
Electrical and Computer Engineering
EECE 259
Laboratory 1 – Digital Systems
Copyright © 2012 PJ Davies
1. To develop the student’s ability to think in terms of turning a requirement for a
digital system into a set of logic gates that will realise those requirements.
2. To become familiar with the idea of simulating a logic circuit using the
Electronics Workbench tool supplied with the course text and available in the Lab
Outline: A control system involved in the manufacturing of ‘widgets’ has 4 inputs
labelled A – D and two outputs Out1 and Out2. Your task is to design a circuit using
AND, OR and NOT gates to implement the following two simultaneous requirements.
Out1 is False (i.e. logic 0) under the following conditions:
A = True, B = False, C = True, D = True. For all other conditions, Out1 is True
Out2 is True (i.e. logic 1) under the following conditions:
Inputs A or D are True. For all other conditions, Out2 is False.
Procedure
Step 1: Design on paper, the logic required to implement these two outputs in terms of
the inputs A, B, C and D and basic AND, OR, NOT gates, i.e. draw the circuit in terms of
gates connected together and to inputs and outputs using wires.
Step 2: Your instructor will give you a Multisim file (a copy is also on the 259 web site
in the labs section) which you should copy to your own computers folder/directory. Open
this file with the National Instruments (NI) Multisim software.
You should see that it has four inputs A-D and two outputs Out1 and Out2. By pressing
the keys A–D on your PC keyboard, you can change the state of the ‘virtual’ inputs A-D,
connecting them either to 5 volts (i.e. a logic 1 or true) or ground/0v (a logic 0 or false) –
see below

Step3: Using the ‘place->component’ menu in NI Multisim software, chose components
from TTL Group / 74LSxx series of devices and place them onto your circuit – see
below. (Hint: the 74LS04N component contains 6 NOT gates, the 74LS08N contains 4,
two input AND gates and the 74LS32N contains 4, two input OR gates).

Step 4: Start the simulation by clicking on the simulation switch
Check your design gives the correct results (i.e. it meets the specification of the problems
defined earlier in the ‘Outline’ by toggling the switches and observing the output lamps.
Step 5: Stop your simulation (otherwise it will use huge PC resources if it runs for a long
time). Now redesign your logic, to use ONLY a combination of NOT gates plus NAND
gates (a Nand gate is an And gate with an inverter wired to the output – the 74LS00N
component contains 4, two input Nand gates). Change your circuit within NI Multisim
and verify that the requirements are still met. Note you will have to think about how to
create an OR gate from a NAND plus NOT gates (the theory was covered in lecture 1)
7404 – Hex Inverters 7432 – Quad 2 input OR

7408 – Quad 2 input AND 7411 – Triple 3 input AND 7421 – Dual 4 input And
7400 – Quad 2 input NAND 7410 – Triple 3 input NAND
7402 – Quad 2 input NOR 7427 – Triple 3 input NOR