1 ENGG 1015 Tutorial Introduction to Electrical and Electronic Engineering – 2012 Fall Semester Time and Venue  Class: P4, every other Monday Tutor  Leon LEI (me): CB 806  Contact me and TAs via Piazza Tutorial materials 

2 ENGG 1015 Tutorial Each class: 40 min. tutorial + 10 min. Q/A Tutorial materials  Regular tutorials  Revision tutorial before examination (Tentatively)  Question banks Homework 2011, 2010 (may be obsolete) Past paper 2011, 2010 (may be obsolete)

ENGG 1015 Tutorial Lecture/Lab materials, announcements  Course site  Moodle  HKU Computer Center  Prompt learning materials help, peer learning  Piazza  Admin help  Piazza (Private post) Extra lab check-off session  TA office hour (CB LG205)  Tue 1530, Tue 1630, Fri 1430, Fri 1530 Textbook  No textbook 3

4 ENGG 1015 Tutorial Systems and Digital Circuits (I) 24 Sept Learning Objectives  Identify concepts of systems  Converts between three representations of digital logic News  Start to have laboratory sessions this week (Suggest to bring your laptop)

Question 1: Top-down vs Bottom-up ItemTop-downBottom-up Driven by system requirement Driven by component integration Construct system by composing smaller parts Construct system by decomposing Generate new ideas from system requirements Synthesize new ideas from existing components Must work with unknown system components as black-boxes 5 Yes

Question 2: Procedures in top-down and bottom-up Making a dinner (Top-down)  Decide the types of dishes according to the location, number of people, time and purpose of dinner  Design dishes according to the types of dishes, diet requirements, kitchen equipment  Find out required ingredients and sauces for each decided dishes  Get all things ready (e.g. buy and clean ingredients, prepare sauces)  Cook every dishes  Bring dishes to the table 6

Question 2: Procedures in top-down and bottom-up Making a dinner (Bottom-up)  Find out the ingredients available  Clean and cut the ingredients according to your own skill and available kitchen equipment  Mix and match available ingredients as different dishes to meet the dinner requirements, such as dietary requirements, location, number of people, time and purpose of dinner, etc.  Cook every dishes by the given kitchen equipment  Bring dishes to the table Making a Rube Goldberg Machine? 7

Question 2: Procedures in top-down and bottom-up Making a Rube Goldberg Machine (Top-down)  Decide the types of stages according to the location, number of stages, and interface of each stage  Design stages according to the types of stages, input and output requirements  Find out the required components for each stage  Get all things ready (e.g. acquire from the TA and technician)  Prepare and assemble each stage  Combine each stage together  Fine-tune the connection between stages 8

Question 2: Procedures in top-down and bottom-up Making a Rube Goldberg Machine (Bottom-up)  Find out the components available  Mix and match available components as different stages to meet the project requirements such as types of stages according to the location, number of stages, and interface of each stage etc.  Prepare and assemble each stage by the given equipment  Combine each stage together  Fine-tune the connection between stages 9

Quick quiz 1 10 What is the only set of input conditions that will produce a LOW output for any OR gate? Any one of the input is LOW Any one of the input is HIGH All inputs are LOW All inputs are HIGH

Quick quiz 2 11 What is the only input combination that will produce a HIGH at the output of a five-input AND gate? Any one of the input is LOW Any one of the input is HIGH All inputs are LOW All inputs are HIGH

Quick quiz 3 12 What logic level should be applied to the second input of a two-input AND gate if the logic signal at the first input is to be inhibited (prevented) from reaching the output? A LOW input will keep the output LOW A LOW input will keep the output HIGH A HIGH input will keep the output LOW A HIGH input will keep the output HIGH

Representing logic operations Each function can be represented equivalently in 3 ways:  Truth table  Boolean logic expression  Schematics 1st semester, 2011 Digital Logic - ENGG K. Wong 13 Truth Table Boolean Expression Schematics

14 Conversion of three representations Truth table  Try every 0/1 combinations of every input variables Boolean expression  Simplification (Next tutorial) Logic circuit  From Boolean expression  Using AND/OR/NOT gates  Alternative: Bottom-up approach

15 Bottom-up: Construct NOT gate, AND gate and OR gate from NAND gate Conversion between NOT, AND, OR, NAND i) ii) iii)

16 Question 3: From logic equations For the expression, construct the corresponding logic circuit, using only AND, OR gates and INVERTERs (NOT gate).

Draw the circuit diagram to implement the expression Draw the circuit diagram that implements the expression using gates having no more than three inputs. 17

Question 3: From logic equations Boolean expressions  Truth table and logic circuit (AND/OR/NOT) 18

Question 3: From logic equations Boolean expressions  Truth table and logic circuit (AND/OR/NOT) 19

20 Question 4: From truth tables Derive the Boolean expression of the output x in terms of the input Construct the logic circuit using AND gates, OR gates, and INVERTERs.

21 Solution 4 1. Construct A/B/C 2. Construct not A/B/C 3. Construct AND gates 4. Construct OR gate 123 4

Question 4: From truth tables Truth table  Boolean expressions and logic circuit 22

Determining output level from a diagram 23

Question 5: From logic circuits 24

Question 5: From logic circuits 25

Quick quiz 4 26 What is the output expression of the following logic- circuit diagram?

Quick checking True or false  An AND gate output will always differ from an OR gate output for the same input conditions. Lecture: Tutorial: 27 False