Download Basic Digital Logic 2 Review

Basic Digital Logic 2
Combinational Logic
Created for the Western Canadian Robotics Society
Paul Godin
[email protected]
February 2004
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Basic Digital Logic 2
Review
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Review
◊ Digital Electronics makes use of 2
states:
◊ Logic High, or “1”
◊ Logic Low, or “0”
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Review
◊ There are 3 basic digital gates:
◊ AND
◊ OR
◊ NOT
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Review
AND, where ALL inputs must be “1”
for the output to be “1”
OR, where ANY of the inputs can be “1”
for the output to be “1”
NOT (or the Inverter) where the
output is the opposite
(compliment) of the input.
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Review Questions
What is the outcome of the following:
1
1
1
1
0
1
0
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Basic Digital Logic 2
Basic Combinational Logic, NAND
and NOR gates
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Combinational Logic
◊ A circuit that utilizes more that 1
logic function has Combinational
Logic.
◊ As an example, if a circuit has an
AND gate connected to an Inverter
gate, this circuit has combinational
logic.
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Combinational logic
◊ How would your describe the output
of this combinational logic circuit?
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NAND Gate
◊ The NAND gate is the combination
of an NOT gate with an AND gate.
The Bubble in front of the gate is an inverter.
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Combinational logic
◊ How would your describe the output
of this combinational logic circuit?
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NOR gate
◊ The NOR gate is the combination of
the NOT gate with the OR gate.
The Bubble in front of the gate is an inverter.
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NAND and NOR gates
◊ The NAND and NOR gates are very
popular as they can be connected in
more ways that the simple AND and
OR gates.
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Exercise 1 – a bit challenging
Complete the Truth Table for the NAND and NOR Gates
NOR
NAND
Input
Output
Input
0
0
0
0
0
1
0
1
1
0
1
0
1
1
1
1
Output
Hint: Think of the AND and OR truth tables. The outputs for the NAND and NOR are inverted.
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Exercise 2 – more challenging
◊ Turn the NAND and NOR gates into
inverter (NOT) gates. Include a
switch for the input.
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Basic Digital Logic 2
Chips and Gates
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Basic Digital Chips
◊ Digital Electronics devices are
usually in a chip format.
◊ The chip is identified with a part
number or a model number.
◊ A standard series starts with
numbers 74, 4, or 14.
◊
◊
◊
◊
7404 is an inverter
7408 is an AND
7432 is an OR
4011B is a NAND
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Chips
◊ Basic logic chips
often come in 14-pin
packages.
◊ Package sizes and
styles vary.
◊ Pin 1 is indicated
with a dot or halfcircle
◊ Numbers are read
counter-clockwise
from pin 1 (viewed
from the top)
Pin 14
Pin 8
Pin 1
Pin 7
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Chips
◊ Chips require a
voltage to function
Pin 14
Pin 8
Pin 1
Pin 7
◊ Vcc is equal to 5
volts and is typically
pin 14
◊ Ground is typically
pin 7
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Chips – Specification Sheet
Voltage
The voltage and
ground pins must be
connected for the
device to function.
Check the specification
sheet to make sure.
Ground
Diagram from http://www.onsemi.com
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Chips – Specification Sheet
A
B
C
D
Diagrams from http://www.onsemi.com
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Wiring a chip
IN
IN
Vcc
OUT
Vcc
Probe
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Useful Resources
◊
◊
◊
◊
Textbooks on Digital Electronics (used is ok!)
Electronics Workbench or other electronic simulation
software
Craig Maynard’s Virtual Vulcan
The following web sites:
◊
◊
◊
http://learnat.sait.ab.ca/ict/digi240_godin/default.htm
http://learnat.sait.ab.ca/ict/cmph200/Default.htm
http://learnat.sait.ab.ca/ict/cmph200_godin/default.htm
◊
◊
◊
http://focus.ti.com/docs/logic/logichomepage.jhtml
http://www.onsemi.com
http://www.national.com/
◊
◊
◊
http://www.play-hookey.com/digital/
http://www.crhc.uiuc.edu/~drburke/databookshelf.html
http://www.digikey.ca/
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Lab Exercise
◊ Using the experimenter’s boards,
connect the circuit provided to you
in the following pages.
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Layout of the SK-10
Experimenter's Board
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Layout of the SK-10
Experimenter's Board
Flat Side
7400
Wires
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Logic Diagram of Lab
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End of Basic Digital Logic 2
Copyright WCRS and Paul Godin
For non-profit use only
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