Basic Digital Logic 2Combinational Logic : 1 Basic Digital Logic 2Combinational Logic Paul Godin
February 2004 Created for the Western Canadian Robotics Society Basic Digital Logic 2 : 2 Basic Digital Logic 2 Review Review : 3 Review Digital Electronics makes use of 2 states:
Logic High, or “1”
Logic Low, or “0” Review : 4 Review There are 3 basic digital gates:
NOT Review : 5 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. Review Questions : 6 Review Questions What is the outcome of the following: 1 1 0 1 0 1 1 Basic Digital Logic 2 : 7 Basic Digital Logic 2 Basic Combinational Logic, NAND and NOR gates Combinational Logic : 8 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. Combinational logic : 9 Combinational logic How would your describe the output of this combinational logic circuit? NAND Gate : 10 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. Combinational logic : 11 Combinational logic How would your describe the output of this combinational logic circuit? NOR gate : 12 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. NAND and NOR gates : 13 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. Exercise 1 – a bit challenging : 14 Exercise 1 – a bit challenging Complete the Truth Table for the NAND and NOR Gates NAND NOR Hint: Think of the AND and OR truth tables. The outputs for the NAND and NOR are inverted. Exercise 2 – more challenging : 15 Exercise 2 – more challenging Turn the NAND and NOR gates into inverter (NOT) gates. Include a switch for the input. Basic Digital Logic 2 : 16 Basic Digital Logic 2 Chips and Gates Basic Digital Chips : 17 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 Chips : 18 Chips Basic logic chips often come in 14-pin packages.
Package sizes and styles vary.
Pin 1 is indicated with a dot or half-circle
Numbers are read counter-clockwise from pin 1 (viewed from the top) Pin 1 Pin 7 Pin 14 Pin 8 Chips : 19 Chips Chips require a voltage to function
Vcc is equal to 5 volts and is typically pin 14
Ground is typically pin 7 Pin 1 Pin 7 Pin 14 Pin 8 Chips – Specification Sheet : 20 Chips – Specification Sheet Diagram from http://www.onsemi.com Voltage Ground The voltage and ground pins must be connected for the device to function. Check the specification sheet to make sure. Chips – Specification Sheet : 21 Chips – Specification Sheet Diagrams from http://www.onsemi.com A B C D Wiring a chip : 22 Wiring a chip Vcc Vcc IN IN OUT Probe Useful Resources : 23 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://www.digikey.ca/ Lab Exercise : 24 Lab Exercise Using the experimenter’s boards, connect the circuit provided to you in the following pages. Slide 25: 25 Layout of the SK-10 Experimenter's Board Slide 26: 26 Layout of the SK-10 Experimenter's Board Flat Side Wires 7400 Logic Diagram of Lab : 27 Logic Diagram of Lab End of Basic Digital Logic 2 : 28 End of Basic Digital Logic 2 Copyright WCRS and Paul Godin
For non-profit use only