EG 1003 Introduction to Engineering and Design Digital

EG 1003: Introduction to Engineering and Design Digital Logic Circuits

Overview Ø Objectives Ø Background Ø Materials Ø Procedure Ø Report / Presentation Ø Closing

Objectives Ø Understand logic gates and digital logic circuits Ø Design combinational logic circuit ØActivate under specific conditions ØTest with Lab. VIEW ØTest using NI-ELVIS prototyping board

Logic Functions Ø AND - “All or nothing operator” ØOutput high (1) only when ALL inputs are high (1) Ø OR gate - “Any or all operator” ØOutput high (1) when at least ONE input is high (1) Ø NOT operator – “Inverter” ØOutput always opposite of input ØOnly one input and one output

Logic Functions Logic Function AND OR NOT Logic Symbol Boolean Expression A • B=Y A+B=Y A=Ā Truth Table Inputs Output A B Y 0 0 1 1 1 0 0 1 1 1 0 - 1 1 - 0

Sample Problem Ø ATM machine has three options: ØPrint statement ØWithdraw money ØDeposit money Ø ATM machine will charge $1. 00 to: ØWithdraw ØPrint out statement with no transactions Ø No charge for: ØDeposits without withdrawal

Truth Table INPUTS W P 0 0 0 1 0 1 1 1 1 D 0 1 0 1 OUTPUT C 0 0 1 1 1 0 1 1 A truth table displays all possible input / output combinations. INPUT OUTPUT P = Print C = Charge W = Withdraw D = Deposit 0 = “do not” 0 = $0. 00 1 = “do” 1 = $1. 00

Boolean Equation P 0 0 1 1 INPUTS W D 0 0 0 1 1 OUTPUT C 0 0 1 1 1 0 1 1 Outputs with a value of “ONE” are kept C PWD = + PWD

Karnaugh Maps (K-maps) C = PWD+ PWD 0 0 PWD 0 1 1 0 PW PW P W PW 0 D 1 D 0 0 1 1 1 0 _ you loop three Why can’t you switch PWthe and PW? adjacent 1 s in the top row together?

Karnaugh Maps (K-maps) C = PWD+ PWD 0 0 0 1 1 0 PW PW P W PW 0 D 1 D 0 0 1 1 1 0 NOTE: Circle neighboring ONES in powers of 2. Try to find the greatest amount of “neighbors. ” Only overlap circles as a last resort!

Simplified Boolean Equation D D PW 0 0 PW PW PW 1 1 1 0 _ _ _ Opposite PWD values cancel out 1 1_ 1 1 PWD 1 __ _ 1 PWD PWD C= W _ + PD

Simplified Boolean Equation D D PW PW Opposite values in circles cancel out 3_ _ _ PWD _ =W Step 2 PWD 1 4 _ _ Step PWD 1 __ = PD PWD C = W + PD

Combinational Logic Circuit W P D _ PD C =W + PD

Integrated Circuits (ICs) Ø Used for implementation of combinational logic circuits ØUse TTL family (transistor logic)

IC Identification

Materials for Lab Ø Computer equipped with Lab. VIEW Ø NI-ELVIS II+ Prototyping Board Ø DIP Switch Ø Hook-up Wire

Problem Statement Ø A farmer has 2 barns Ø 3 items: fox, hen, corn ØItems can be in any barn, in any combination ØConcerns: ØProtect hen from fox ØProtect corn from hen Ø Design alarm system using digital electronics. Alarm sounds when: ØFox and hen are in same barn ØHen and corn are in same barn

Problem Statement Ø Design combination logic circuit for alarm system: ØUse least amount of gates and input variables (cost effectiveness) Ø Logical circuit output connected to LED ØLED “on” indicates alarm activation ØLED “off” indicates no problem (alarm off) Ø Fox, hen and corn must be in barn 1 or barn 2 ØPresence in barn 1 = 1 ØPresence in barn 2 = 0

Procedure • Truth Table • Boolean Expression • K-Map • Simplified Boolean Expression • Logic Circuit • Lab. VIEW Simulation • NI-ELVIS Ø Truth Table ØDetermine input and output variable (s) ØHow many combinations are there? ØComplete truth table on a sheet of paper

Procedure • Truth Table • Boolean Expression • K-Map • Simplified Boolean Expression • Logic Circuit • Lab. VIEW Simulation • NI-ELVIS Ø Boolean Expression ØGather all combinations that produce a 1 for output ØCreate a Boolean expression from these smaller expressions (independent conditions)

Procedure • Truth Table • Boolean Expression Ø K-Map ØCreate a K-Map table • K-Map • Simplified Boolean Expression • Logic Circuit • Lab. VIEW Simulation • NI-ELVIS ØOnly have one variable change state at a time between adjacent boxes ØUse the Boolean expression to fill in the 1’s

Procedure • Truth Table • Boolean Expression Ø Simplified Boolean Expression ØUse K-Map to circle groups of 1’s • K-Map • Simplified Boolean Expression • Logic Circuit Ø 1’s may only be circled in powers of 2, starting from largest possible combination and working downward • Lab. VIEW Simulation • NI-ELVIS ØWrite new simplified expression

Procedure • Truth Table • Boolean Expression • K-Map • Simplified Boolean Expression • Logic Circuit • Lab. VIEW Simulation • NI-ELVIS Ø Logic Circuit Diagram ØUse new simplified Boolean expression to design a logic circuit ØHave TA check/initial work

Procedure • Truth Table • Boolean Expression • K-Map • Simplified Boolean Expression • Logic Circuit Ø Lab. VIEW Simulation ØCreate logic circuit in Lab. VIEW based on theoretical work ØFront panel Ø 3 control switches represent input variables Ø 1 Boolean indicator shows output • Lab. VIEW Simulation • NI-ELVIS HINT: some Lab. VIEW comparison functions are: NOT AND OR

Procedure • Truth Table • Boolean Expression • K-Map • Simplified Boolean Expression • Logic Circuit • Lab. VIEW Simulation • NI-ELVIS Ø NI-ELVIS Prototyping Board ØDo NOT electrically connect anything until TA has reviewed your work ØConnect +5 V and ground to the DIP switch ØUse created logic circuit and IC chip diagram to wire actual circuit on the prototyping board ØBe sure to connect each of the ICs to “Ground” and “+5 V” (circuit power) ØConnect final output to an LED. **VCC is an acronym: **Voltage at the Common Collector (+5 V)

Assignment: Report Ø Individual Report Ø Title page Ø Discussion topics in the manual Ø Scan in data and lab notes Ø Original tables and work should be legible Ø Include screenshots of Lab. VIEW front and back panels

Assignment: Presentation Ø Team presentation Ø Professional-looking tables Ø Include screen shots of your programs ØPhoto of functioning LED assembly Ø Explain steps taken to complete lab ØBe prepared to provide walk-through Ø Include lab data Ø Refer to “Creating Power. Point Presentations” found in Online Manual

Closing Ø Have all original data signed by TA Ø Each team member should have turn using software Ø Submit all work electronically Ø Return all unused materials to TA