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ELE 202 - Electrical, Computer & Biomedical Engineering

1. i CIRCUIT DESIGN E LABORATORY TABLE OF CONTENTS Page Contents 2 Syllabus 3 Introduction 4 Lab 1 Basic Electronic Instruments and Measurements 8 Lab 2 Oscilloscope and Function Generator 12 Lab 3 Combinational Circuits CMOS Logic Gates 15 Lab 4 Sequential Circuits Flip Flops and Counters 17 Lab 5 Electronic Design Automation with Mentor Graphics 26 Lab 6 Some MSI Chips and State Machine Design 30 Lab 7 Sequential Circuit Design Automobile Taillights Control 32 Lab 8 Static Random Access Memory SRAM 33 Design Project Introduction Suggested Topics and Project Management SEMESTER Fall 2000 INSTRUCTORS Peter Swaszek Ying Sun DEPARTMENT Electrical and Computer Engineering University of Rhode Island Copyright 1998 2000 University of Rhode Island Course title Catalog description Prerequisite Text book Course Objectives Laboratory Assignments Class lab schedule Course outcomes Assessment Methods Relationship of course to program objectives Professional component ELE 202 Digital Circuit Design Laboratory 1 1 Laboratory experience in digital electronics logic design projects using standard integrated circuits Laboratory 1 credit Credit or concurrent enrollment in ELE201 Laboratory manual CMOS data book To Understand Know how to use basic electronic measurement instruments and how to measure DC voltage current and logic states To Question
2. 3 Logic functions From the truth table derive the logic functions Express every output as a function of the input Simplify these logic functions by use of Boolean algebra Karnaugh map or computer software The Karnaugh map K map will be the most frequently used technique in this course 4 Prototyping Implement the circuit on the proto board 5 Testing Measure the input output relations and validate the circuit against the original truth table Assignment 2 Design of a seat belt warning buzzer Problem statement Devise a gate circuit to sound a warning buzzer in an automobile if the ignition key is ON and either the driver s seat belt D is not buckled or the passenger s seat belt P is not buckled and a pressure switch S indicates that that seat is occupied Build and demonstrate the working of this circuit The output of the buzzer circuit can be connected to an LED indicator on the proto board Or to make it more dramatic use the speaker driver circuit as shown in Fig 3 2 Notice that an open collector TTL NAND gate 7403 is used instead of a regular TTL NAND gate 7400 See below for a brief explanation of open collector Function Generator 5V on Proto Board TTL Output Figure 3 2 A logic indicator circuit by use of the function ae generator and the speaker on the proto board f Test Point Open Collector Circuitry The TTL7403 is a quad NAND gate IC with open collector circuitry Its pin assignment is shown
3. Consider alternative designs of digital circuits for solving engineering problems To Design Use SSI MSI LSI chips and software tools to design digital circuits To Lead to participate in a team based design project To Communicate Learn communication skills through oral presentation written proposal abstract and final report for the project Basic Electronic Instruments and Measurements Oscilloscope and Function Generator Combinational Circuits CMOS Logic Gates Sequential Circuits Flip Flops and Counters Electronic Design Automation with Mentor Graphics Some MSI Chips and State Machine Design Sequential Circuit Design Automobile Taillights Control Static Random Access Memory SRAM ONO PON Laboratory 3 hours week Knowledge of basic electronic instrumentation and digital circuits a Skills of conducting experiments and building prototypes of digital circuits b Ability to design digital circuits for solving specific engineering problems c Consideration of alternative designs of digital circuits I Ability to manage a design project with a small team d Ability to identify formulate and solve an engineering problem with a state machine approach e 7 Ability to conduct oral and written presentations of the course project in a comprehensive but succinct way g 8 Ability to use software tools including schematic design and circuit simulation to design digital circuits k Ore OT
4. a SPDT switch b DIP switch with c DIP switch with pull up resistors pull down resistors 5V 5V 10KQ 10KQ logic 1 0 Figure 3 1 Wiring of DIP acta switch and SPDT switch for o to gate generating logic signals all input 5V Notice that pull up or pull down resistors need to be used with the DIP switch Otherwise a short circuit 5V directly to ground would occur and damage the proto board Depending on how many input signals you need you can wire up S2 and S3 without resistors to provide 2 inputs or you can wire up S1 with resistors to provide up to 8 inputs For output you can either set up the LED logic level detector in Fig 1 3 or you can simply use one of the 8 LED indicators on the proto board Since all the 6 chips under testing have the same pin assignment the same wiring can be used for all chips Each time when you move on to another chip just carefully lift the chip and insert the new one without disturbing the wires Once the wiring is done it should take only a few minutes to run through all the chips 13 Designing Combinational Logic Circuits The general procedure is as follows 1 Specifications Understand the problem and make sure the problem can indeed be solved by use of a combinational circuit Identify and assign symbols to the logic variables Specify them as inputs and outputs of the combinational circuit 2 Truth table Assign logic levels to the outputs for every combination of the inputs
5. 2 second You may have to adjust the intensity and focus controls to keep the display in focus with the right brightness In this setting we see that the display is actually a spot The horizontal system moves the spot from left to right across the screen at a speed given by the sec div control knob This control is called the sweep generator with the setting of 2 s on the sweep generator the spot moves across the ten divisions on the screen in two seconds When the spot reaches the right edge the horizontal system pulls it back in the retrace period the spot stays in the left for a holdoff time and then repeats the cycle During retrace and holdoff we do not see the spot because the display system blanks it out Note the tremendous range of the sweep generator With one turn of a knob we can measure the time interval between events which occur 5 seconds apart and events which occur 50 nanoseconds apart In order to do this we have to make the spot mark the instant at which the first event occurred and the instant at which the second event occurred This can be done by coupling signals from the events into the vertical system This system deflects the spot in the vertical direction The distance between the vertical jumps on the screen will be proportional to the time interval between the two events Vertical System Coupling the input signal to the vertical system is done through the BNC connector at the bottom of the channels In the BNC conne
6. About the Design Project After you finish the eight required laboratories you will apply the knowledge you have learned to a design project The project specification may read something like this Design the control logic for a programmable electronic lock At the moment this may not make much sense to you Hopefully around midterm you will identify a topic for your project and begin to specify the steps towards solving it The procedure and ideas for the design project will be given and discussed in the ELE202 recitation sessions The project will be conducted in five phases 1 proposal 2 abstract 3 oral presentation 4 demonstration and 5 documentation written report About Electrical Safety Current Through Human Body Amperes Improper connection of circuitry or 1 burns 1 5A improper use of electronic instruments can cause severe consequences including e Savere burns damage of circuit components damage of breathing stops electronic instruments fire injury and Ventricular fibrillation even death The table on the right death 100 300 mA summarizes the hazards caused by the 0 1 re AE a i L extreme breathing difficulties different levels of electrical current flowing a C breathing upset through the human body C labored breathing severe shock muscular paralysis cannot let go oni painful maximum let go j mild sensation current 10 mA lt maximum harmless current 5 mA _ threshold
7. You should consider the constraints of time and materials available in our lab You want to make sure that you can finish the project by the end of this semester and according to the schedule given later Choosing the topic for the project is the first step and a crucial decision A good idea can make the project a lot of fun to do In general you should think about a project that looks smart not big Keep in mind that we will be using the bread board for wiring The bread board does not provide reliable connections You might have already learned the lesson in the hard way A large bread board prototype is prone to fail For example you may think that building a digital clock is easy The design is easy indeed But just to wire the hour minute second display it would require 6 seven segment LEDs plus 6 BCD to seven segment drivers and 6 BCD counters Never mind about the time it would take what do you that the probability of having a bad connection in such bread board prototype would be You will get some help in choosing the project topic in the recitation sessions A list of some project ideas is also provided below But again you are encouraged to develop your own idea and use your imagination Project Ideas In the following we provide you with some ideas suitable for the ELE202 project These suggestions are intended to stimulate your own ideas You are by no means obligated to choose one from the list The suggestions are also very g
8. divide by N counter 14520 dual binary up counter 14021 8 bit shift register 14526 4 bit binary down counter 14040 12 bit binary counter 14529 dual 4 channel data selector 14042 quad transparent latch 14551 quad 2 channel mux 14053 triple 2 channel mux 14555 dual 1 of 4 decoder 14495 hex to seven segment driver 14560 NBCD adder 14508 dual 4 bit latch 14585 4 bit comparator Assignment 2 Sequence generator By choosing appropriate combinational logic we can make the register go through a prescribed set of states This is of great importance when we wish to generate sequences of states which are used for controlling the flow of information through a digital system For example the output waveforms obtained in the ring counter of exercise 2 would be useful when we need three phase clocking However in that circuit we had to initialize the register to obtain the proper output In many cases we would like to have the counter go into the proper sequence after an initial transient no matter what state it started from when switched on As a final problem in this assignment on designing with D flip flops we do the next exercise We want to have a 2 bit counter which after initial transients goes through the sequence 0310310 no matter what the initial state is Draw a state diagram for this counter Design and implement this counter Assignment 3 State Machine The counter is a special case of the state machine The counter goes through a pr
9. 1 Hz clock from the proto board so you can observe the count on the LED display Try both up counting and down counting Then switch the multiplexer to the DIP switch Enter a BCD code and observe the LED display What happens when you enter a number beyond 9 in the range from 1010 to 1111 An important technique for digital design is function partitioning The task to be performed by the entire system is usually too complicated to implement at once We should first separate the main task into multiple functions and address the individual functional units In a sense it s like a divide and conquer approach If we can find the right chip for a particular function the design can be simplified and the chip count can be significantly reduced Therefore it is important that you know what chips are available to perform what functions There are many other MSI and LSI chips which are very helpful for digital design It is obviously impossible for us to go through all of them in this lab We suggest that you browse through the functional selection guide from p 2 2 to 2 5 in the CMOS Logic Data book for the various types of logic chips The following is a list of some of the useful MSI chips that we have in stock in our lab 14008 4 bit full adder 14510 BCD up down counter 14014 8 bit shift register 14511 BCD to seven segment driver 14016 quad analog switch mux 14512 8 channel data selector 14017 decade counter 14516 binary up down counter 14018
10. As with all instruments the more intelligent practice you put in the greater your mastery of the tool Inverter Transfer Characteristic In Lab 1 we measured the transfer characteristic of an inverter point by point and plotted the results on graphs The oscilloscope has a special x y mode which should allow us to plot the transfer characteristic curve directly on the display of the oscilloscope Depending on the model of the oscilloscope the x y mode is usually selected by turning the time resolution knob all the way counterclockwisely But be careful not to leave a stationary bright spot on the display When there is no input in the x and y channel 1 and 2 the electron beam remains stationary at one spot If this happens you should immediately move the spot off the screen using the position knobs or turn the intensity to a very very low level A better way to do this is to leave the time resolution knob on the normal two channel mode when you set up the inverter circuitry and turn to the x y mode when all signals are available and applied to the oscilloscope To plot the transfer characteristic of an inverter set the function generator to sweep the 0 to 5 voltage range The triangular waveform should be appropriate for this purpose This 0 5 volt triangular wave is sent to the input of the inverter and also to channel 1 x axis of the oscilloscope The output of the inverter is sent to channel 2 y axis of the oscilloscope therefore cre
11. Be Gos O 1 Laboratory reports 2 Oral presentation of the project 3 Proposal abstract and final written report of the project This course contributes to Objectives 1 and 2 by equipping students with the necessary background to work in digital circuit design Engineering science 0 5 credit Engineering design 0 5 credit INTRODUCTION About the Labs There are eight required laboratories for ELE 202 Lab 1 begins on Monday of the second week of the semester We will proceed at a pace of one lab every 1 2 weeks The duration for each lab is specified in the lab description that follows Depending on the enrollment you will likely have one or two classmates as your lab partners You will work as a team on one of the six benches in the Digital Electronics Lab Kelley 120 However each of you must submit individual lab reports without collaboration with others Therefore you should understand every detail although you work as part of the team Make sure that you record all the data and graphs necessary for the report A lab report will be prepared for each lab and due one week after the completion of each lab About the ELE202 Recitation You need to register for one of the ELE 202 recitation sessions because the 1 credit goes with a recitation session not the lab itself Starting from the fall 2000 semester the recitations will be used as office hours of the teaching assistants and instructors to answer student s individual questions
12. DeMorgan d version negative logic of a standard library component to achieve a clean mixed mode notation select the component press and hold the right button of the mouse and choose Replace Alternate Symbol You ll have to do this operation possibly a few times to get the right alternate symbol Printing in Mentor You will normally use the k116 laser printer in Kelley 116 Normally when you need to print something from a UNIX shell command interpreter a variation of the command 1p dk116 lt myfile gt is used In Mentor tools before you print anything you must set up the printing system by selecting Setup Printer from the MGC pulldown menu Select Postscript for printing text or to a file and set the name of the printer to k116 Note that this differs slightly from the actual name of the printer QuickSim II The Logic Simulator Once you have entered your design in Design Architect it has passed all of its checks and is registered it is time to see if it actually does what you designed it to do This is done using the QuickSim II QS Mentor Graphics Simulator Tool to verify your design Invoke it by double clicking on the QuickSimll icon of the Tools window in DM Do NOT select the QuickSimll F PGA icon A window will pop up prompting you to enter the name of the design you wish to simulate Click on the Navigator button located all the way to the right on the window i
13. cycle Wire up the counter circuit Drive it with a 100KHz clock and observe the output waveforms on the oscilloscope Verify the result Clock Figure 4 2 Schematic diagram for a MC14013 2 bit ripple counter Notice that we use D FFx2 the 4013 dual D FF chip instead of the Reset 4 10 0 4175 quad D FF chip This is because Set 6 8 0 the ripple counter design requires that Vpp 14 5 V each FF has a separate clock input Vss 7 GND To save some wiring time we demonstrate the ripple counter design with only 2 bits This design can easily be expanded to more than 2 bits With the inverted terminal fed back to the input each flip flop acts like a toggle flip flip T FF the output toggles its state on every positive edge of the clock pulse The external clock drives the first flip flop The output of the fist flip flop Qo drives the clock input of the 2nd flip flop We can keep on extending this ripple effect for more than 2 flip flops The ripple counter also acts like a chain of frequency dividers For example if the clock frequency is 100 KHz we get a 50 KHz square wave at Ap and a 25 KHz square wave at A Draw the schematic diagram of a 4 bit ripple counter in your lab report but you don t need to verify it in the lab Figure 4 3 shows a 3 bit synchronous up counter Notice that you can use the quad D FF chip MC14175 now because all the flip flops in the synchronous counter are driven by a common clock Study the circuit
14. environment variables are set in order to function properly On the ELE system these parameters are automatically set for you whenever you log in however on the ECL system you need to specify the file which includes all of these modifications The following steps must be done for the ECL system only 1 From your ECL home directory type lt editor gt cshrc where lt editor gt represents your favorite text editor such as emacs vi xedit etc 2 Add the following line near the end of the cshrc file source tmp_mnt levl mgstart Save the file and exit your editor 4 Log out then log back in or simply type source cshrc at the Unix prompt to update your system environment variables You are now ready to start running the Mentor Graphics Tools w Please adhere to the following rules e Rule 1 Every component for lab 5 should be in the lab5 directory that you just created e Rule 2 All components should be at the same directory level i e this is a flat directory structure even though logically your design is a hierarchy of components e Rule 3 Except in certain noted cases ALL manipulations of your lab5 directory and its contents should be made ONLY within a Mentor CAD tool usually Design Manager dmgr This is true of ALL Mentor designs and their parent directories Note If you do not follow Rules 1 through 3 the Mentor tools may get confused and may not work right and you may thus wind up having to complet
15. help you getting started You don t have to follow this block diagram if you have a different approach The design problem is often 30 open ended In other words there is no unique solution to a design problem A good design is usually the simplest one that completely meets the specifications First design the circuit on paper We suggest that you simulate and refine the design by use of Mentor Graphics Then build and test the circuit on the hardware platform in the lab Turn signal sequence Joes OFF By Se O ON Bi oS Figure 7 1 Taillight signaling pattern for a right turn RIGHT TURN Taillight decoder driver Right Left Brake System Controller Figure 7 2 System block diagram for the automobile taillight control circuit 31 Lab 8 Static Random Access Memory SRAM Object In this lab we work with a static random access memory study the controls on the chip and learn to transfer data in and out of the RAM 1 week MC6810 This is a large scale integrated LSI circuit containing about 104 transistors Unlike the others we have worked with this is an NMOS chip It takes more standby power and the voltage levels are slightly different But it readily interfaces with CMOS chips so it will not present any problems for us The 6810 is a 128X8 static random access memory chip It has 7 address lines which are used to select 1 of the 128 addresses on chip 27 128 At each address 8 bit data
16. not accidentally apply the wrong voltages when we are PS setting up the connections shown on the right Note that when shielded cables are used Scope Outer GND GND GND GND as in the probes for example there are oa On Sleeve PG PS Chip Probe1 Probe 2 only short stretches of wire at the output l end The reason for this is obvious if you Probe 1 Probe 2 are going to great pains to have the signal go along a shielded path so that it does not pick up noise you want to keep the exposed portions as short as possible Note also the number of leads which are attached to ground From these considerations it is clear we must pay attention to having good solid GROUND connections near our circuit input and output terminals You may find it convenient to have short bare wires and connectors which give you GROUND in your circuit Set the vertical mode controls as follows the left switch to BOTH which activates the right switch and the right switch at ALT Set both selector switches at the bottom to DC You can trigger from CH1 You should see both the input and output signals as the spot will be drawing them alternately on the screen Work with the other positions of the controls to learn what they do The Oscilloscope The above set of exercises are just to get you started using the oscilloscope as a multi purpose tool There are many features we have not even touched upon like AC coupling delayed sweep normal and TV triggering
17. of the design Synchronous Decade Counter Vcc Author Christopher Meynard Date October 2 1996 Course ELE202 Lab Note The 7 Segment was created graphically and did not function in the simulation This component is not available in the compoment libraries 23 Notice that the Mentor Graphics does not have a 7 segment LED display in its component library The one shown above was drawn in just to complete the schematic diagram The 7 segment display won t work in the simulation Requirements and Specifications 1 Create the Decade Counter using Design Architect exactly as shown in the diagram Specifically you will be required to use the following parts from the libraries e s_lib library power supply vcc quantity 1 e Is lib library input port portin quantity 2 e Is_lib library output port portout quantity 4 e Is _lib library 2 Input AND gate 74LS08 quantity 3 e Is _lib library JK flip flop 74LS112A quantity 4 e std_lib library BCD to 7 Segment Display 7448 quantity 1 2 Simulate the Decade Counter using QuickSimll Specifically the trace should include all input signals and all output signals Additionally you must reset the count to zero to initialize the outputs then simulate the counter for 600ns with a clock having a period of 50ns 3 What To Hand In e A print out of the schematic circuit of your decade counter e A trace print out showing the values of all inputs and outpu
18. the same Now that you ve read the Introduction to ELE Computing document there are a few things you should do to setup your account to make life easier on yourself The following steps should only be done ONCE The next time you login everything will operate as it should Directory Setup You need to make a structure to hold your designs for ELE 202 Start by giving ELE 202 it s own subdirectory off of your root directory Type the following cd mkdir ele202 at the Unix prompt Note that on the ECL computers you may need to open an xterm window first before you can type commands since the xterm window may not appear on the desktop by default To open an xterm window click the right mouse button anywhere on the desktop and choose xterm from the pull down menu Now we ll set aside a place where your files for this lab will be stored First change to the ele202 directory by typing the following cd ele202 ls a There should be only two lines shown one with the subdirectory and one with the subdirectory Actually these are not really subdirectories in UNIX command syntax a single period refers to the directory you are 17 currently in and the double period refers to the parent directory of the one you are in You should now be able to make a directory for lab 5 name it whatever you want e g lab5 Hint just use a mkdir command ECL Environment Setup Mentor Graphics requires that the path is modified and certain
19. we have the protoboard on which the chips can be mounted Use the ohmmeter to discover the internal connections in the protoboard Notice that the chips go in straddling the vertical channels in the board In putting the chips into the protoboard or in taking them out do not use force This is another sure way of destroying chips The pins get bent and the chip is useless Always use the insertion and extraction tools which are on your bench if you are not sure the lab instructor will show you how to use them To make connections on the protoboard use 22 gauge solid wire Each bench has been provided with a selection if you need more there are spools of wire and a wire stripper on the back bench Always take a little care in using the board If a pin or a wire breaks off inside the socket it is very hard to take out and the socket is ruined A little practice in using the board is very helpful do not let your lab partner do all the assembling 7404 14049 Inverter TTL SN7404 For this chip jy NC Voc is at pin 14 and ground is at pin 7 1Y 6Y Pin 1 is an input and pin 2 the 6A corresponding output etc see figure on the y NG right We want to measure the transfer Pa characteristic i e the output voltage as a 3Y 5A function of the input voltage Make the appropriate connections Use the fixed 5 V mae supply on the PS503A for providing the power and the PMC variable voltage source for supplying the input voltage Measu
20. Designing a logic level indicator In digital circuits we deal with binary signals i e logic 0 and logic 1 most of the time So it would be convenient to devise a simple indicator to show the logic level of a signal We can use a Light Emitting Diode LED for this purpose The LED emits light when a current flows through it entering at the terminal P and leaving at the terminal N The LED s we use in this lab usually have a maximum current rating of 100 mA The indicator on the protoboard can then be set up as shown on 5V test point the right When the voltage at the test point is OV there is no 7 current flowing through the LED and it is OFF When the test voltage is 5V the LED is ON Choose the appropriate value of the resistance R set up the indicator The resistor R limits the current through the LED Without it the LED would burn out immediately A 220 Q resistor would limit the LED current to about 20 mA Can you confirm this with Ohm s law Assume that the voltage drop across the forward biased LED is about 0 7 volts You can make the LED brighter dimmer with a smaller larger resistance But do not go over the 100 mA limit Notice that we use the TTL inverter 7404 instead of the CMOS inverter 14049 Although the CMOS inverter has good voltage transfer characteristics as shown earlier it is not capable of supplying enough current to drive the LED The TTL inverter on the other hand can sink a high current when its output is
21. Elib You should now see the list of LS part numbers available Select 74ls08 Its symbol will appear in the small window above the palette Use the mouse to position the symbol on the sheet then left click the mouse and the gate symbol will be placed Oh you didn t want to place it there no problem just select it an object appears dotted in white when selected and click the right mouse button Choose Move and place the symbol in a new location Did you prefer the gate where it was the first time If so click the right mouse button again and select Undo If you are happy where it is either left click the mouse on the gate again right click the mouse and choose Unselect or choose Unselect All from the palette so it is no longer selected One thing you may have noticed is that there are some pretty handy features available when you right click the mouse The functions available change depending on whether the gate is selected or not and whether you are on the palette or the sheet You should take a look at some of the other items that appear and try to figure out what they do Most should be very obvious For example to return back to the first palette which appeared on the screen click the right button over the new palette and choose Display Schematic Palette Wiring OK let s connect some virtual wires to the inputs and output of the AND gate Choose the Add Wire button from the palette A small
22. Select Stimulus in the QS palette then choose Add Clock When the window pops up enter 100 for the clock period then choose OK The clock signal has been added to the trace Now unselect the A input and do the same for the B input except give B a period twice that of A 200ns Simulating Your Design Now that you have a stimulus for both inputs we can add the output to the trace and simulate the design Select the output of the AND gate then press the Trace button on the QS palette The output has been added to the Trace window The last thing to do is choose Run from the QS palette and enter 500 for the time to simulate Click OK and the output should now display the response to the stimuli for every instance of time up to 500ns If you ve done everything correctly your trace should resemble that in the figure below Hopefully the results make some sense to you If not ask the TA or professor to explain what happened IV Lab 5 Assignment Synchronous Decade Counter Now that you have a basic idea of how to enter schematics and simulate them it is time for you to practice with a slightly more complex circuit The counter circuit in the figure below is a Synchronous Decade Counter with an asynchronous active low Reset The circuit is to be entered using the Design Architect schematic entry tool The Mentor Graphics QuickSim II simulator is to be used to simulate and verify the correct operation
23. Simply these logic functions by use of Karnaugh maps Other techniques such as Boolean algebra and computer software can also be used when appropriate 6 Prototyping Implement the circuit on the proto board 7 Testing Measure the input output relations and validate the circuit against the original truth table Assignment Luxury Car Taillights Controller Use LED s to simulate the six taillights three on each side of the card Use toggle switches for the turn signals one to indicate a left turn the other to indicate a right turn As shown in Fig 7 1 for a right turn the three right hand lights should be activated and the left hand ones should be off The three right hand ones should cycle on and off taking about a second for each cycle The operations for a left turn are analogous If both switches are set the emergency flasher should be activated since the driver obviously does not know what he or she is doing There should also be a separate emergency flasher ENABLE When the emergency flasher circuit active all six lights should flash on and off in unison with a frequency of about 1 Hz Further refinements are possible e g if the brake pedal is pushed all the lights are on continuously except if a turn signal is on In the latter case the three lights for the turn signal operate normally and the other three are on continuously A system block diagram is provided in Fig 7 2 Notice that this block diagram is intended to
24. ating an electronic plot of the curve just like what you did on paper in Lab 1 You will need to adjust the position and voltage scale on channel 1 and 2 for proper visualization of this curve Plot the transfer characteristics with the oscilloscope for both the TTL and CMOS inverters 7404 and 14049 A more advanced digital oscilloscope may have an interface to a printer or a plotter for direct screen dump Since we don t have such setup in the lab yet you need to sketch what you see on the oscilloscope on paper and put it in your lab report For each of the transfer characteristic curves you may notice that there are two traces slightly apart from each other This should be particularly noticeable for the TTL 7404 and is due to the fact that the interver output is slightly different when the input is swept up 0 to 5 V and down 5 to 0 V The phenomenon is analogous to the hysteresis typically observed in electromagnetics It is usually frequency dependent Change the frequency of the function generator and observe its effect on hysteresis Briefly describe your observation in the lab report Lab 3 Combinational Circuits CMOS Logic Gates Object In this assignment we study the basic logic gates AND OR NAND and NOR We design and realize some simple combinational logic circuits by using these gates 1 week Proto Board PB 503 The proto board has built in power supplies We shall be using only the fixed 5V supply Use the m
25. below Also shown is a simplified circuit for the typical output stage of a TTL logic gate The circuit consists of a load resistor a diode for protection purpose and a PNP transistor In the case of a open collector gate the internal load resistor is absent allowing the designer to add an external load the speaker in this case 7403 Bie 1A Vcc Logic 0 Logic 0 1B 4A Logic 1 Open circuit 0 1Y 4B B c B C 2A 4Y E Emitter E 2B 3A H B Base C Collector 2Y 3B GND 3Y j Simplified Open collector typical TTL TTL output output Lab 4 Sequential Circuits Flip Flops and Counters Object In this lab we learn the basic component for sequential circuits the flip flop We learn how to implement counters by use of the D flip flops 1 week Assignment 1 Shift register and ring counter MC14175B is a quad D flip flop chip It contains 4 positive edge triggered D flip flops with asynchronous reset Study the specification sheets especially the truth table on p 6 197 of the CMOS Logic Data book Note that there is only one common clock input and one common reset input which apply to all 4 flip flops The reset input is asynchronous active low Asserting the reset input with a logic O will reset all the Q outputs to O immediately independent of the clock signal In this assignment we use a 4175 chip to implement register and ring counter Study the schematic diagram in Fig 4 1 and then wire it up on the proto board LED logic indicato
26. cal gates which perform the same logic function and each gate takes 2 input signals The pin connections are the same for all these chips Vpp 5V pin 14 Vss Ground pin7 Inputs 1 2 Output 3 Inputs 5 6 Output 4 Inputs 8 9 Output 10 Inputs 12 13 Output 11 We want to find out the logic function performed by the gate in each of the different chips Since the four gates in a chip are identical it is only necessary to make measurements on one of them per chip Assignment 1 Basic Gates We want to set each input to 1 or 0 for each of these conditions we want to see if the output is 1 or 0 The obvious thing to do is to set up our LED logic level detector at the output and arrange to apply the proper input states The first assignment of this lab is to complete the following truth table Input Output A B AND OR NAND NOR XOR XNOR opo eR Or This is quite easy for this particular assignment but let us start learning some good design rules now Wiring the Protoboard In all digital design projects itis essential that all wiring be neat and orderly It must be immediately obvious what the interconnections are on the protoboard rat s nest wiring is not permitted The following suggestions are helpful 1 Mount all chips with the indentation on top This might lead to lengthier wires in some cases but the ease of identifying pin numbers at a glance makes it well worth while 2 If possible avoid running wires over a chip it make
27. ckSim II tool which will be described later Before we move onto the simulation aspect though let s discuss some of the less obvious things that DA provides and which you need to know in order to get through the whole design process successfully Checking The design has to pass certain checks before it can be successfully registered and saved Do this by using the Check pulldown menu and selecting sheet Once DA has checked your design a window will pop up giving a report of the check All errors must be fixed Warnings may or may not need to be fixed for your design to work depending on the warning For example an unconnected output triggers a warning but this may be perfectly fine for your circuit like having an unused Q output from a flip flop You should look at the warnings and make your own determination Registration Once you have the schematic entered and checked you must register it i e make it known to the rest of the world This is done automatically when you save the sheet which you should do often DURING design entry in case something goes wrong the system dies so that you don t lose all of your work Save the sheet by selecting Save from the File pulldown menu 21 Making aSymbol In order for your component s design to be used by some other component you need to give your design a symbol Making a symbol is like packaging your design into a chip so that all the imple
28. ctor the signal is carried by the central pin and the sleeve is ground The oscilloscope is agrounded instrument You could connect the scope to the circuit under test with just a wire but this is to misuse the instrument The connection would load the circuit in an unpredictable fashion the wire would act as an antenna and pick up stray signals and the scope would not be able to perform to its full capacity Connecting input signals to the vertical system is always done through aprobe 8 The Probe The probe consists of a resistive cable and a grounded shield In order to put the signal into the scope connect the probe to the channel input with the mating BNC connectors Note that in making this connection you have to press in and then rotate CW to lock the connection in place Some of the probes have a 1X and a 10X adjustment In the 10X position the signal is attenuated by a factor of ten before being fed into the scope In this assignment we use the probe in the 1X configuration The end of the probe has a spring connection with which you can clip the probe to a wire carrying the input signal This clip is delicate do not try to force it to grab binding posts etc it is just meant to be clipped around wires In case you want to get the signal from the pin of an IC chip you can remove the top plastic sleeve on the probe This will expose the probe tip which can then be pressed on the pin to acquire the signal In this case of course yo
29. ctually building it In the following Section introduces you to the ELE system Section II provides a brief tutorial to get you going with four of the Mentor Graphics programs and Section III has the details on the Lab 5 assignment itself I Getting Started By this time you should have an accounts on the ELE computing systems The main place to work is in the ELE computing lab located on the first floor of the Kelley Hall room 115 This is also possible to use the Engineering Computer Lab ECL located in the new Kirk building The Mentor Graphics software resides on the ELE computer system It is therefore a little bit more complicated to access the software from ECL via the network The following assumes that you are in the ECL the differences with Kelley 116 will be noted Most likely you will finish this lab completely on the ELE computer But it is helpful to know how a complex software system like Mentor Graphics can be run over the network Most UNIX programs will also work on character based terminals i e over the phone lines but many including our Mentor Graphics CAD tools need to be run on workstations Setting Up Your Directory System To begin with read the Introduction to ELE Computing document distributed in the lab by your TA or professor Follow the instructions for logging in given in that document Note that the instructions handed out are for your ELE account not your ECL account the procedure for ECL is basically
30. d f you give your report to someone who has not done the lab you would expect him or her to duplicate exactly what you have done according to your report The report doesn t have to be long it should be concise and sufficiently comprehensive to address all the questions observations results and designs in the lab The report should be neat and well organized If your hand writing is not very legible you should prepare the report with a typewriter or more preferably a word processor Consult your lab instructor for the specific format of the report Lab 2 Oscilloscope and Function Generator Object In this assignment we learn to work with the oscilloscope and the function generator We display the transfer characteristic of an inverter and measure the time required for a signal to propagate through the inverter We use the function generator and the oscilloscope to study the input output relations of the CMOS AND gate and OR gate 1 week The Oscilloscope This is an instrument you will be using very often The chart hung up in the back of the Laboratory gives you a first lesson in using the oscilloscope The operator s manual for the oscilloscope is in the folder on your bench The following steps are suggested as a way of getting started once you complete them you should proceed to do more measurements on your own so that you get familiar with every control on the instrument The following description is for the Tektronix 2215 60 MHz osci
31. develop a timing diagram wire up the circuit and verify the result by use of the oscilloscope 4081 4070 4175 ANDx4 XORx4 D FFx4 Counter enable E Ay Figure 4 3 3 bit synchronous up counter The chip count of this circuit is 3 4070 4081 and 4175 Since each chip contains 4 gates flip flops we could have built a 4 bit counter without additional chip To save some wiring time we build a 3 bit counter which should be sufficient to demonstrate the design Remember to tie the Reset line for the 4175 D FF s pin 1 to logic 1 If it is left floating the FF s may be Output locked in the reset state carry A2 Lab 5 Electronic Design Automation with Mentor Graphics Object In this assignment we learn to use electronic design automation EDA tools for designing digital circuits Digital circuits are input to the computer by schematic capture software Circuit behaviors are determined by computer simulation using a hardware description language called VHDL 2 weeks Object The main objective of this lab is to become familiar with the ELE department s UNIX computing environment and to gain experience with the Mentor Graphics system s logic timing functional simulator Additionally you will design and simulate a basic counter namely a Decade Counter using the Mentor Graphics software package The knowledge you gain from this lab will be immediately utilized in the next lab when you first simulate your design solution before a
32. dialog box pops up indicating that you are now adding a wire to your sheet Now place the cross hairs of the cursor onto one of the inputs and left click the mouse This anchors the wire to the input of the gate Move the cursor to the left of the gate and extend the wire to an appropriate length When you think the wire is long enough double left click the mouse to complete that segment of wire Wire the other input pin in a similar fashion Let s do the same for the output but this time instead of double clicking the mouse to terminate the wire single left click the mouse and move the cursor either up or down If you did it right you should have bent the wire in one direction or the other Bend it once more so it is horizontal again Finally terminate this wire Each pin should now have a wire connected to it so guess we are done using our wiring tool for now Simply click the Cancel button on the small dialog box to put your wiring tool away The cross hairs should have disappeared when you returned the cursor over the sheet Lastly unselect everything Adding ports Now let s add input ports to the input wires and an output port to the output wire To do this select the portin component in the Is_lib library and place it so it is connected to one of the input wires Now you can either left click the portin symbol in the upper right corner to grab another one for the second input or you can right click the mouse with t
33. e DM502 digital multimeter can be used as a voltmeter an ammeter or an ohmmeter by dialing to the appropriate function and range However do not use the instrument as an ohmmeter in a live circuit i e a circuit with a power supply Note also that you cannot leave the instrument in the circuit and change its operation from measuring voltage to measuring current by depressing the appropriate control button Voltage is measured across an element current flows through an element IC Chips The integrated circuit IC chips that we will use contain many elements 5 i 5 i 7 connected together and packaged in a dual 3 12 3 14 A 22 in line package DIP They may have 12 14 i o 5 50 16 or 24 pins to which we can make external 6 9 6 11 E connections These are numbered as shown 7 8 T 8 17 on the right The chips need power to work id 1 and this is supplied by connecting a 5 V 1 E power supply to the chip the ground terminal of the supply to the ground pin of the chip and the 5 V terminal to Vcc or Vpp pin as the case may be In most but not all cases if the chip is mounted with the indentation on top the bottom left pin is ground and the top right is VDD or Vcc One sure way to destroy a chip is to connect it backwards so be sure to check the pin diagram of the chip before turning on the power In all our work with chips we shall work only in the range from 0 to 5 volt Protoboard To make it convenient to build circuits with many IC s
34. e chips apart from the inputs for the logic function desired some other inputs called select strobe control etc are provided to make the chip more versatile in its applications It is important in digital design to learn what MSI chips are available and how they can be used One has to learn exactly what they do and how the various controls are employed In many problems the use of available MSI chips makes the design cheaper and better Assignment 1 BCD Counter System Let s learn some MSI chips by working on a practical design problem We are going to build a one digital BCD counter The output is shown on a 7 segment LED display The MSI chip MC14511 converts the 4 bit BCD code to the 7 segment display code it also outputs enough current to drive the LED segments TCG3056 is a seven segment display Each segment is illuminated by a light emitting diode The diode has an anode and a cathode When a positive voltage gradient is applied across the LED from anode to cathode called forward bias the LED converts electrical energy to light photons and lights up the segment All cathodes of the LEDs are connected together the common cathodes go to GND The signals to the anodes are labeled from a to g Some LED displays also have a decimal point An input signal of 1 will cause the segment to light up and signal 0 will leave it dark As shown in Fig 6 1 the ten decimal digits can be displayed by lighting up the appropriate segments As in the case
35. ed access type s If the mgpack file is not there type mgpack lt mg_directory gt lt your_username gt ele202 where lt your_username gt is your user log in name If the mgpack file is already there simply type cp lt mgdirectory gt mgpack lt your_username gt ele202 and the file will be copied 3 Whether you copied the directory structure or used ftp to send it to a different account the mgpack file must be unpacked in order to make use of the files This is easily done by typing mgunpack lt mg_directory gt mgpack at the Unix prompt You are now ready to start using the files in their new location 4 Finally the following Unix commands may be useful for copying the entire content of a directory from one account to another account In the source account issue the command chmod R o r lt directory_1 gt This command change the access protection mode on lt directory_1 gt allowing other users to copy this directory In the destination account issue the command cp r lt directory_l gt lt directory_2 gt This command copies the entire content of lt directory_1 gt to lt directory_2 gt You may need to provide the full access path for lt directory_1 gt if you are in a destination account different from the source account 25 Lab 6 Some MSI Chips and State Machine Design Object In this lab we work with some MSI Medium Scale Integrated chips We interface the output of a decade counter to a seven se
36. ed with the starting of the repetition of the signal This last condition is achieved by the trigger controls When the blanking period is ended the spot does not start till it is told to do so by the trigger In our first setting the SOURCE to the trigger was INT This tells the trigger to look at INT There the switch was set at CH1 The trigger then takes the signal which is coming into CH1 The slope and level settings tell the trigger to operate when this signal has reached such and such a level and is increasing At this instant the trigger starts the spot on its trace By this means we got a steady picture of the shape of the signal In the last exercise we used an external signal to tell the trigger when to act That signal came from the FG itself which sends out trigger information synchronized with its pulses Dual Channel Vertical System Controls The scope has two input channels for the vertical system So far we have used only channel 1 we could just as well have used channel 2 as both channels are similar It is also possible to have two input signals and use both channels simultaneously For example we can apply a signal to the input of an inverter and look at both the input and output waveforms The input can go into CH1 and the output to CH2 Set up the FG to give 5V 100 usec pulses with period 200 us Before going ahead with the next step it PG ee Bs PS a 5 might be wise to turn off the power on the instruments so that we do
37. ely re enter your design following the rules to keep Mentor happy Quitting Mentor Graphics Cleanly Mentor Graphics Tools do not have a Quit option from any pull down menus You may be tempted to simply log out or destroy the window when you are done using the application If you do this there is a chance that not all of the Mentor Graphics processes which are running will receive the kill signal so that even after you log out they may continue running in the background wasting valuable system resources Therefore to cleanly exit any of the Mentor Graphics Tools when you are done using them simply click the middle button of the mouse on the upper left corner of the window and choose Exit Window Il Introduction to the Mentor Graphics Tools Mentor Graphics is a very powerful software package used to design and more importantly to simulate designs in order to verify their functionality The software was donated to the University of Rhode Island and we are authorized for up to ten copies This means that if ten people are currently running the software you will not be able to start the application Please note that ELE 202 is not the only class which will be using Mentor Graphics so it may happen more than a few times that all the licenses are being used If this happens you will just have to wait until one becomes available The software itself is being used in industry today and thus is a very practical application for you to lear
38. eneral If you choose one of them there are still plenty of room for variation and creativity 1 Up down stop watch Use a push button switch for input and a 7 segment LED for output The operations of the stop watch start stop and reset are controlled by quick oy clicks of the push button By holding down the push button for more than say 1 second the stop watch toggles between up counting and down counting If you can design the 1 digit stop watch you should be able to extend the design to more digits But as we discussed early we are not interested in the size of the circuit It s the intelligence that counts The tricky part here is to differentiate two types of input i e the quick click vs the long depression by use of a single push button switch 2 Electronic lock A 4 bit code is entered via DIP switches When the push button is pressed and the correct code has been entered the LED lights up to indicate the unlocking Press the button again to lock To change the code unlock the system first Press the button and hold it down for more than a second and the LED changes from on to flashing Enter the new code via the DIP switches and press the button again to lock 3 Serial communication Enter a 4 bit number via DIP switches When the push button is pressed the number is sent out bit by bit with a parallel to serial register The serial data is received by a serial in parallel ou
39. escribed sequence of numbers states step by step on the command of a clock A state machine is more general and can be much more complicated in its operation In addition to the clock there are other input signals to control the progression of the states For example a state machine may stay in a certain state doing nothing but waiting for a certain signal to occur Thus as an alternative to constructing a sequence generator from a counter the state machine is more a general and powerful approach The state machine is designed to implement a state diagram A state diagram is similar to a flow chart of a computer program At each 28 state the state machine evaluated the present state it s in and the present input from which the next state is determined The hardware organization of a state machine is shown in Fig 6 3 The slash on the signal line indicates that there can be more than one signal Of the three functional blocks both the next state decoder and the output decoder are combinational circuits The middle block is a sequential circuit consisting of a flip flip of flip flops driven by a clock The state machine can be designed following a systematic approach as discussed in the lecture Input F F Present State Output Figure 6 3 Block diagram for a Next state machine Notice that the next ey state decoder and the output decoder are all combinational circuits The system memorizes the present state by use of the flip f
40. gment display using a latch decoder driver chip We practice the skills of sequential circuit design a special counter and a state machine It is important that you finish the design of the two circuits on paper before you come to the lab 2 weeks MSI Combinational Circuits In our previous assignments we used SSI small scale integrated chips These had about ten gates per chip and external pins for all the inputs and outputs By putting together many chips and interconnecting them we could make large combinational logic circuits to solve any design problem It is possible to put a very much larger number of gates on a chip But if we just did that and gave external pins for all the inputs and outputs we would not gain much since the size of the actual silicon chip is negligible in comparison to the size of the package and pins The size of the package would keep growing with the number of gates and the external wiring job would be just as difficult But there are many types of combinational logic circuits that occur frequently in design problems In such cases it is worth while to build a package with all internal connections on chip and have pins only for the external inputs and outputs and Vpp and GND of course The chip is then specified by stating the input output function This could be done with a truth table but this is usually so large that it is hard to interpret without some additional description of the chip In most of thes
41. he Read Write control is set for read pressing the Strobe button brings the stored data out and displays it on the LED indicators A system controller state machine should be implemented to sequence the events in the system LED indicators oo0oo0oo0o0000 Clock Read Write System Strobe controller 8 bit latch 4508 debounced push botton 8 bit DIP switch 6810 RAM 7 bit DIP Figure 8 1 Block diagram J a switch address for the RAM data entry circuit 32 ELE202 Digital Circuit Design Project Introduction At this point you should have acquired the basic skills for digital circuit design We would like to see what you can do as we turn you loose The design project can be conducted all by yourself or you can find a partner The project team is not necessarily the same as the lab team We prefer a team of two people one is lonely and three is a crowd If you choose to do it on your own you don t need permission However if you would like to form a 3 member team you will need to obtain the instructor s permission and justify that the intended project really requires the effort of 3 people The difference between the project and the labs is that you make the rules for the project The role of the instructor is to assist you in the process We encourage you to use your imagination and pursue your own interest However we want to make sure that the project is neither too simple or too ambitious
42. he portin component on the sheet selected and choose Copy from the pull down menu Place this one at the other input For the output port select portout from the library and follow the same procedure These ports indicate the external connections as seen from outside this sheet much the same way you only see the external pins which are available on real chips in the lab 20 Labeling The default name for all wires is NET but since it is not a good idea to have them all labeled the same we will rename the ports so they are more meaningful Rename the two inputs A and B and call the output A_AND_B To do this you must first tell Mentor Graphics that you wish to be able to select component properties By default you are not allowed to do so Press the Set Select Filter button on the schematic palette and when the window appears click the Properties box then click OK Next select one of the input port names currently called NET then right click the mouse and choose Change Values A dialog box will pop up at the bottom of the screen Type the new net name in the New Value text window then click OK Do the same for the other two ports Remember to have only one name selected at a time and no components including ports Documentation We should give our schematic a title so everyone including yourself will know what it is we have entered For this example it is qui
43. hown in the figure Submit the one page proposal to the recitation instructor one for each team qi _ 43 gt Title of Your Project in Bold Face Mary Smith and John Doe Dept of Electrical and Computer Engineering University of Rhode Island Kingston RI Abstract Due two weeks from end of semester The abstract is in the same format as the proposal By the time the abstract is due you should have finished the project or at least the major part of it You should summarize the design and result of your project The abstract needs to be submitted electronically It will be published and distributed to everyone involved in ELE201 and ELE202 You may still need to print it out on paper just to check the Start the proposal abstract here following a blank line Use 12 point Times font Set the text width to 4 3 inches Adjust the length of the text such that the total total length of the abstract But do not submit any hardcopy Rather generate a text only version of the abstract and e mail it to SUN ELE URI EDU one for each team Oral Presentation Schedule to be assigned last week of semester Each team will present the project to the class The format of the presentation is a 5 min talk followed by a 3 min discussion Demonstration Schedule to be assigned last week of semester Each team must demonstrate the operation length is within 6 inches Write the entire proposal abstract in one paragra
44. is stored The chip has an 8 bit bidirectional three state data bus DO to D7 The R W line controls the direction of data flow There are 6 chip select lines CSO to CS5 some of them are asserted high and others asserted low All 6 CS lines must be asserted otherwise the chip is disabled and the data bus is in the high impedance state You can use CS0 to enable the chip and connect other CS lines to their asserting logic levels To access the memory a specific timing sequence should be followed See the timing diagrams and specifications on the 6810 data sheet The general sequence is Apply an address to the address bus Assert the chip select Write data to or read data from the memory The memory access time for 6810 is about 360 ns That means you have to wait for that amount of time from asserting address to accessing data The memory access time is mainly for the addressing logic inside the memory chip to decode the address and connect the specific data storage to the data bus Assignment Design and build a data entry circuit for the 6810 A block diagram for the system is suggested in Fig 8 1 Again you can follow you own idea as long as the specifications are met The address is selected via 7 DIP switches The data can be entered into the RAM by setting the data with another 8 DIP switches The Read Write control is set for write By pressing the Strobe button the data on the DIP switches is entered into the selected address When t
45. lloscope The Tektronix 2235A 100 MHz oscilloscope is very similar If you have another type of scope on your bench the description of the front panel controls may not be accurate but the basic operation should be the same Please note that we are in the process of upgrading the oscilloscopes If you have a different newer oscilloscope on your workbench the specific instructions pertaining to the oscilloscope may not apply but the general principle remains the same Getting Started The controls can be divided into four sections the display the vertical the horizontal and the trigger system controls Turn the power on You should see a horizontal line on the display If there is none depress Beam Finder and position the blob in the center of the screen with the vertical position knob above CH1 and the horizontal position knob above HORIZONTAL MODE Then release Beam Finder and you should have the trace If not ask for help from instructor Display System Controls Use the intensity focus and vertical and horizontal position knobs At all times the scope should have a clear well focused trace which is just bright enough to be seen with comfort The trace should never be too bright with a surrounding glow this decreases the life of the display You should never have abright stationary spot on the screen This burns the spot in and ruins the display Horizontal system controls Move the sec div knob step by step CCW till you are at
46. lops Output Flip Flops Decoder Design and implement a state machine based on the state diagram shown in Fig 6 4 Build and demonstrate the circuit Use a debounced push button switch on the Proto Board for the input X Run the clock at a relatively slow rate say 1 Hz Show the present state 2 bits with the LED indicators such that you can verify the circuit by stepping through the state diagram X is an input from the debounced a 4 state machine with an input X The outputs are the two X Ee co push button switch X state variables y1 and y0 Figure 6 4 State diagram for 29 Lab 7 Sequential Circuit Design Automobile Taillights Control Object In this lab we design a sequential circuit to control automobile taillights that show a special pattern for direction change You should finish your design on paper before you come to the lab so that the lab time can be devoted to building and testing your circuit 1 week Designing Sequential Logic Circuits There are different approaches to engineering designs such as systematic vs heuristic and top down vs bottom up The choice of an appropriate design approach depends on the available time and resources the experience of the engineers and the problem itself The recommended approach for this lab is a systematic top down approach The general procedure for the design of a state machine is as follows 1 Problem statement Understand the problem and make s
47. low Use this LED indicator for the next part of the lab Two coupled inverters In the CMOS inverter chip if the output of one inverter is connected to the input of the second and the output of the second to the input of the first see Fig 1 2a what do you expect will be the voltages at the various pins Try to work out what they will be and then do the measurement to find out if you were right Notice that the TTL inverter won t work in this case Use the LED indicator in the previous step to check the output in the coupled inverter circuit Three coupled inverters Now set up a coupled circuit with three inverters i e the output of the first is the input to the second the output of the second is the input to the third and the output of the third is the input to the first see Fig 1 2b Check the voltages with your indicator If your circuit works properly you should observe that the LED is on but appear to be much dimmer than usual logic 1 state Can you explain this Figure 1 2 Schematic diagram for two a 5V Test dii b Test el coupled inverters a Touch the input wire momentarily to 5V GND to register a 1 0 and then let the input floating For e gt o lSo MoA gt three coupled inverters b do not tie the ia input to either 5V or GND Lab report A written report for this lab will be due a week from the day you do the lab The report is intended to be a technical documentation for the lab performe
48. mentation details are hidden and all that is seen to the outside world are the inputs and outputs exactly like the real IC s you have been using in the lab Symbols can be generated manually which is highly tedious or automatically which takes seconds To do the latter select Generate Symbol in the Miscellaneous pulldown menu The symbol will appear in its own window It must also be checked and registered In addition you should give the symbol a name NOTE a component must have no more than one 1 symbol Any more and DA gets confused and your circuit won t work If you add or remove an input or output to the component you must recreate the symbol but MAKE SURE the replace old symbol button is active in the dialog box when you do it Using Your Designs Since we are not creating any elaborate designs in this lab you will not need to use your design to make more complicated ones However you may decide to or be required to simulate your project before wiring it and in that case you might want to build your project in small components Among other benefits this approach generally makes debugging much easier To use a component you created earlier in a new component like a 1 bit register invoked 8 times to form an 8 bit register just call up the symbol of the old component and place it as you did with the standard library parts in a sheet of the new component Symbol Variations DeMorganizing To use a
49. n Bold Browser Mentor s Online Documentation This handout attempts to spell out in great detail exactly what you need to do in order to complete this lab The TA will also be in the lab with you to help in getting familiar with the Mentor Graphics environment and in fielding questions as they come up In addition you may have had a brief introduction to the Mentor Graphics environment in one of the recitations All of this will help you however there are bound to be times when you will have a question on how to do something and nobody will be around to help you That is what the online documentation is for and you must be 18 able to use it effectively in order to find the solutions to your problems Keep in mind that there is no way anyone can fully explain everything or anticipate all of the inevitable questions and problems that will undoubtedly arise Virtually all of Mentor s documentation is online You can print it out but do so sparingly if at all since you have a small print quota The online documentation is accessed via a special program called Bold Browser To crank up the browser type bold_browser at the Unix prompt After awhile its window will appear What you see initially is the Bookshelf which lists the different online documents within categories When you have time you should take a look at this document turning the pages with the gray button s on the right side of the top bar of the sub window In general
50. nd terminal is usually color coded black In some instruments there is a third terminal the chassis ground in addition to the red and the black terminals The chassis ground terminal sometimes color coded green connects to the metal case of the instrument and to the ground of the electrical system in the building Your have an option to tie your circuit ground black terminal to the chassis ground green terminal or not In some other instruments you don t have this option The circuit ground is internally connected to the chassis ground This means that the ground terminal is connected to the case and also through the power cable to the ground terminal of all electrical power being supplied to the building It is important to realize that if you are using such devices all points marked ground are shorted together There can be only one ground in acircuit In connecting together various grounded instruments and supplies we have to make sure that a power supply never gets shorted i e have its two output terminals connected together In such a case we are asking the supply for an enormous amount of power which might destroy something All the supplies in the laboratory are well designed and will turn themselves off or display a red light should such a contingency arise However this may not happen soon enough to prevent some damage and in any case it is bad practice to have to rely on this safety measure The two output terminals of apower s
51. of sensation perception threshold 0 001 1mA Lab 1 Basic Electronic Instruments and Measurements Object In this assignment we learn to work with power supplies voltmeters ammeters and ohmmeters We shall measure the V I characteristic for a resistor and the transfer characteristic for a TTL and a CMOS inverter We set up an LED voltage level indicator for CMOS chips This lab should be completed in a session 1 week Power Supply This supplies electrical power at a specified voltage across its terminals This voltage may be fixed or variable For example the Tektronix PS503A on your bench has one pair of output terminals which supplies power at 5 Volt and another pair whose output voltage can be adjusted between 0 and 20 Volts The PMC power supply is another voltage power supply available on our work bench Voltmeter A voltmeter measures the voltage drop from the point to which its red terminal is connected to the point to which its black terminal is connected Tektronix DM502 digital multimeter can be used as a voltmeter with the appropriate control buttons depressed Suppose a voltmeter measures x Volts when connected across points A and B If we interchange the leads from the voltmeter which are connected to A and B then it will measure x Volts Ground The ground in a circuit provides a voltage reference point at 0 Volt The ground is usually indicated by GND or one of the two symbols shown on the right The grou
52. of the LED a limiting resistor is needed in series with the element For 5V supply and the LED displays used in this lab the value for the limiting resistor should be around 200 Q Notice that without the limiting resistors the LED displays would burn out immediately a Gh g 123456189 Figure 6 1 Standard choice of the LED segments for displaying the digits from 0 to 9 26 The input to the 7 segment driver comes from two different sources either a BCD up down counter MC 14510 or a 4 bit DIP switch Here we encounter an important problem in digital circuit design i e the bus contention problem We have two output devices counter and DIP switch sharing the same bus the input lines of the BCD to seven segment driver We cannot simply tie the output lines from the counter and the DIP switch together Because if we have two output lines short circuited one may output logic 1 5V and the other may output logic 0 ground A short circuit from 5V to ground spells trouble This is called bus contention which must be avoided in digital design There are several solutions to the bus contention problem Standard solutions include the use of multiplexers three state output devices and analog switches More detail will be covered in the recitation session For the present problem we use a quad 2 channel multiplexer chip MC14551 to switch the connections from the counter and from the DIP switch to the 7 segment driver A multiplexer or data
53. onnect it from the TRIGGER OUT of the FG503 to the EXT input of the trigger section of the scope See what happens Obviously something gets out of synchronization Let us think out carefully what is happening The spot starts on the left and moves to the right at a speed set by the horizontal sweep In this case it is taking 50 us times 10 divisions i e 500 us to get across During this time the vertical position depends upon the voltage at the CH1 input If this goes up and down the spot goes up and down Thus the oscilloscope draws a graph of voltage versus time on the screen But note that the graph is all done and complete in 500 usec Now what does the spot do It is retrace and holdoff time during which it is blanked out and gets to the left of the screen This takes some time it is not accurately fixed but depends on the settings and will probably have a little jitter in it Then the sweep starts again the spot starts moving from left to right and traces out a second graph With the settings we have the spot is drawing about 2000 graphs in a second If we are to see a steady picture on the screen it is obviously essential that the spot draw the same graph every time 1 This means the signal must be a repetitive one i e the signal waveform repeats itself as time goes on 2 The spot starts drawing the graph starting at an equivalent point on the signal shape each time around i e the starting of the sweep must be synchroniz
54. ow Design Architect Schematic Capture and VHDL Entry Design Architect DA is the tool you ll use to enter your designs You will only enter designs via the schematic capture part Perhaps in future classes you will be introduced to VHDL and enter designs in that manner but for now you have enough to learn VHDL by the way is a hardware description language used for describing digital electronic systems To start DA double click on the design_arch icon in Design Manager s Tools window Once it has started expand the DA window to take up almost the whole screen otherwise it may be hard to see some of the window s contents You are now ready to begin using DA Schematic Capture Schematic capture is the process of entering a design into the Mentor system so that it can be manipulated and in particular simulated This is done by drawing a schematic on the DA screen This process consists basically of two intertwined steps 1 placing the components e g logic gates flip flops etc on the sheet and 2 connecting them with virtual wires At this point we will step through a whole sequence of events using a trivial running example that should illustrate most of the features you need in order to complete the schematic entry portion of this lab Keep in mind that DA has much more to offer than just what is described here You will use these same steps when entering the Synchronous Decade Counter example described later Crea
55. ph Begin with a short explanation of what the project is about Give some more technical specifications For abstract you should have finsihed the design at this time Summarize the final design and report any significant findings from your project of the project The demonstration will take place in the lab and will be open to anyone who is interested Documentation Due final exam day for ELE201 Each team must submit a written report for the project Unlike the lab report the project report is one for each team The report is meant to be a technical documentation of your project The report should be succinct but comprehensive such that all technical details are included 34
56. re input and output voltages with the DM502 multimeter In taking the data you will find it useful to graph the points as you make the measurements You might run over the range in big steps first and then examine the places where things are changing rapidly by taking finer steps in that range Inverter CMOS MC14049 The pin connections for this chip are not the same as for the 7404 see figure above Graph the transfer characteristic for this inverter Power up this chip by connecting VDD to 5 volts and Vss to ground Note that the labeling for the power and ground pins is related to the semiconductor technology Vcc collector of a TTL transistor Vpp drain of a MOS transistor and Vgs source of a MOS transistor It is clear why these chips are called inverters A low voltage at the input produces a high voltage at the output and a high voltage at the input produces a low voltage at the output Actually these are called hex inverters because there are 6 inverters in each chip the pins 1 3 5 8 10 12 being the inputs and pins 2 4 6 9 11 13 the 6 corresponding outputs From your measurements on each chip find the points at which the transfer characteristic has unity gain These are the points at which AV oy is equal to AVin On the graph they are the points at which the slope of the transfer characteristic has unit magnitude We shall use these observations later when we consider noise margins for different families of IC chips
57. rows mark the units etc It is also very good practice to plot your data on a graph as you take them so you can see what is happening to the output as you change the input From your measurements it should be clear that the voltage across a resistor is proportional to the current through it This is the ubiquitous Ohm s Law V Rx where V in Volt and in Ampere R is called the resistance of the resistor and the unit Volt Ampere is called an Ohm Find the resistance of the resistor you worked with Power We said that if an element has a voltage V across it and a current flowing through it then it absorbs power VI Remove the ammeter from the circuit and have the power supply connected directly across the resistor We are doing this to protect the ammeter Gradually increase the voltage to about 8 or 10 Volts and then feel the resistor It is evident that the power absorbed by the resistor generates heat in it If you put on too high a voltage you might burn out the resistor which is why it is suggested that you do this gradually Ratings All elements will have some power voltage and current ratings In designing with these elements we will have to bear these values in mind and see that they are not exceeded For example the resistor you worked with is a 1 2 Watt resistor which means that the resistor can handle a maximum power dissipation of 1 2 Watt Multimeter Measure the resistance of the resistor you used with the ohmmeter Th
58. rs Figure 4 1 Schematic diagram for a 3 bit shift register ring counter Use the debounced push button on the proto board to enter the clock pulses manually A 10KQ pull up resistor should be used as shown Use S4 to introduce logic 1 to Do Use So to reset the circuit Use S3 to close or open the feedback loop Without the feedback D b nce the circuit acts like a shift register With push button the feedback the circuit acts like a ring rr counter L MC14175 Vpp 5V pin16 Vss GND pin 8 Reset the circuit first With the loop open deposit a single 1 using S4 and shift it from Qo to Q4 and to Q by entering the clock pulses via the push button Reset the circuit again This time try to deposit two 1 s and shift them to the right This circuit is a shift register Reset the circuit Deposit a 1 and shift it to Qo Now close the loop with S3 and rotate the 1 around the loop Repeat the exercise with two 1 s in the loop This circuit is called a ring counter for obvious reason It is import that you use a debounced switch to enter the clock The glitches from the mechanical vibrations of the switch are eliminated by a switch debounce circuit to ensure a single pulse from each depression of the button Without the switch debounce circuit multiple pulses will be generated from a single depression and you won t be able to control the operation You can replace the debounce push button with just a switch and see wha
59. ry gt mgpack 2 You can now either ftp this file to your ELE account or your partner can copy it to his her account e f you wish to ftp it to your ELE account you should first make sure that you have a sub directory on your ELE account named e e202 or some equivalent to keep your ELE 202 files separate from everything else From your local ele202 directory execute the command ftp ele at the Unix prompt You will be prompted for your user name and password for your ELE account Once you are logged on to the remote host the prompt changes to ftp gt Type cd ele202 The remote directory is now updated Change the file transfer type to binary by typing binary Next type put lt mg_directory gt mgpack 24 and your file should be sent over Lastly type bye to close the ftp session and return back to the normal Unix prompt e f you wish to copy your partner s work into your own directory on the same system follow these guidelines First change into your partner s directory by typing cd partner_username gt ele202 at the Unix prompt Note that if you are not allowed access to that directory your partner will have to change the file permissions to allow you to access it This is done by using the chmod command Type man chmod to find out more about using this command Incidentally the man command gives you help on just about every Unix command available It can be quite useful so you should learn to use it Assuming you are allow
60. s it hard to insert and extract the chip 3 On each side of the central channel on which the chips are mounted there are two vertical strips of connected sockets Use the outer two to run the VDD line and the inner two to run the ground line The little U shaped wires you have on your bench enable you to connect a pin to VDD or GROUND neatly 4 Use red wires for connecting to VDD black wire for connecting to GROUND Use yellow wire for the signal In some designs you may want to distinguish one set of signals from another for example you may want one set to be input and another set to be output In this case you may want to use yellow blue and or purple wires for your signals Later we will be using a clock use white wire for clock signals 5 Whenever possible use short connections which lie along the protoboard However do not hesitate to use longer connections if it will make it easier to follow the signal flow through the system 6 You will find the longnosed pliers very useful in inserting and extracting connecting wires There are spools of wire and a cutter and stripper on the back bench Measurements We want to be able to switch from 1 to 0 at the inputs We can do so with the flick of a switch On the proto board we can use the DIP switch S1 and the single pole double throw SPDT switches S2 and S3 To generate the logic 0 1 signals the DIP switch or the SPDT switch need to be wired to 5V and ground Study the following diagrams
61. selector is a logic circuit that accepts several input channels and allows only one of them at a time to go to the output The routing of the desired data input to the output is controlled by SELECT inputs sometimes called control address or strobe inputs The block diagram of the design in this assignment is given in Fig 6 2 along with detailed schematic diagrams for the individual components in the system Study these diagrams carefully and try to understand how the overall system functions Block Diagram for Assignment 1 Seven Segment LED Display Common Cathode Common Anode SPDT DIP Switch x4 Rop O when switched to RIGHT Switch Quad 2 Channel Multiplexer BCD to Seven Segment Driver p 6 405 p 6 256 BCD Up Down Counter eens SV oe p 6 248 5V WO o X0 o YO o oW 9a Up Down Z0 o o X A j Clock Q1 A oC B sd Q2 B W1 o C Res PI Q3 C X1 D oi P2 Q4 D y1 og P3 Z1 P4 Figure 6 2 Block diagram of a BCD counter system and schematic diagrams for system s components 27 Although the essential information for wiring the BCD counter circuit is included in Fig 6 2 you should study the original data sheets in the CMOS Logic Data book on pages referred to above You may also want to draw a complete schematic diagram to help you wire the circuit and understand the system better Construct the circuit and test it Switch the multiplexer to take the counter outputs Drive the BCD counter with a
62. t happens Counters A counter in general is a register which goes through a prescribed series of states driven by a clock signal For an asynchronous counter such as the ripple counter the clock inputs of the flip flops are not driven simultaneously from a common external clock Rather some of the flip flips are clocked by outputs from other flip flips or itself As a consequence all the flip flops do not switch exactly at the same time They are slightly out of synch because the accumulation of delays through the chain of flip flops results in a ripple effect of the switching The accumulated delay slows down the circuit and might also cause timing problems and glitches in the outputs A synchronous or parallel counter gets around these problems at the expense of additional circuitry The basic principle of operation of synchronous counters is to use combinational logic with the present state of the flip flops to present the correct input at each flip flop for its next state 15 Assignment 2 Asynchronous and synchronous counters Figure 4 2 shows a 2 bit ripple counter in which A4A gives the down count and B Bo gives the up count In other words A4A should cycle through the sequence of 00 11 10 and 01 B4B should cycle through the sequence of 00 01 10 and 11 Study how the circuits work by drawing the timing diagram for the clock Aj Ap By and Bo Start by drawing several clock cycles and show how A Ao and B Bo change cycle to
63. t may not be visible so you ll have to move the cursor back and forth over the right edge of the window to encourage Mentor to move the window to the left so it is visible When the Navigator window comes up navigate to your design directory and select the part you just entered Press OK drop the new window on the desktop and expand it so it takes up most of the screen Select Open Sheet from QS s palette and the sheet containing your design should pop up Before we can simulate the design we must set up the timing diagram Once that is done we can run the simulator and verify that the circuit behaves as expected Adding an Input Stimulus We need to basically verify the truth table of the AND gate In order to do that we need to vary the two inputs so we obtain all four possible combinations The output will then react to these stimuli and we can compare that reaction to the known response of an AND gate If we ve entered everything correctly we should be able to verify that we do indeed have an AND gate 22 Select input A on the schematic the wire connected to A becomes a dashed white line Now select the WF Editor in the QS palette Choose Edit Waveform A new Trace window pops up and the input signal A has been added Currently there is no stimulus for this input so the trace shows a dashed blue line indicating an unknown value Let s apply a clock at this input with a 100ns period
64. t register and parallel to Serial Serial to Parallel displayed on LEDs 33 present state 4 State machine with control memory The next state decoder and the output decoder of a state machine can be combined and implemented by use of a memory The memory can be used to implement combinational circuits Each combination of the input signals corresponds to an address The stored data corresponds to the truth table of the output signals In essence we can store the entire state table into a memory chip Based on the RAM data entry circuit of lab 8 you can add additional logic for implementing state machines as shown This is a very powerful concept because the state machine is programmable It can perform different tasks based on the truth table you enter in the RAM address _ input Flip flops Manual data entry Project Management The project will be conducted according to the steps below The specific due dates for each step will be announced in the recitation session Proposal Due around mid term Submit a one page description of what you propose to do for your project Give a short but informative title Put down your name or names if you work as a team Describe what you want to build Write a little bit about the detailed specifications The proposal should be typed single spaced by use of the 12 point Times font and fit into a frame of 4 3 inch wide and 6 inch long as s
65. te obvious but for a complex circuit it may not be immediately apparent what the circuit represents We should also add some information about who entered it when it was entered or last modified and perhaps for what purpose To add text such as this to the sheet click the Text button on the main palette select the Add Comment option and type your comment into the small text window that pops up When you are done typing place the information in a convenient location on your sheet Repeat this for each line of text you wish to add to your sheet In addition to text various shapes can be added MY AND GATE to your schematic As a simple example draw a 74LS08 rectangular frame around your name date and purpose Accomplish this by selecting Draw a a from the palette and choosing Add Rectangle a A_AND_ Click and hold the left button of the mouse where you want to start the rectangle then drag the Author Christopher Maynard mouse to the opposite corner and release the Date October 18 1996 button When you have finished entering your Purpose ELE 202 Lab 5 Example 1 design it should look something like the circuit shown on the right Ill Manipulating Your Schematic Once you are done entering your design you can do several things with it One obvious thing is to simulate it to verify that you connected everything together correctly Simulation is done using a different application namely the Qui
66. the vertical scale Note that with the 1V scale the reading from dotted line to dotted to dotted line on the display is 5 Volts The Function Generator To get a slightly more complicated signal into the scope let us try to use the function generator FG503 Note that the output is not grounded if you look carefully you will see the insulation between the sleeve of the connector and the case Use the oscilloscope to monitor the output of the FG503 You can connect the oscilloscope and the FG503 by use of the proble or simply a direct BNC to BNC cable The setting of the oscilloscope is the same as before except sweep generator at 50 us Adjust the front panel control of FG503 to generate a 0 5 Volt square wave of 10 KHz You should see a square wave on the display If you do have a problem getting the trace you might try adjusting the level knob in the trigger section If you still have a problem get the instructor to help Trigger Section Controls Set up the function generator and scope to see 5V pulses of 100 us period on the display Set the sweep generator at 50 us so we see a few pulses Now turn the level knob in the trigger section all the way CCW and notice what happens Get the steady picture back again by going back to the previous setting Turn the A amp B INT switch to CH2 and see what happens Set the switch back to CH1 Set the source to EXT and see what happens This time instead of going to the old setting take a BNC to BNC cable and c
67. ting aSheet Your circuit must be entered into a page which is called a sheet To start a new schematic you need to open a new sheet for it Press the Open Sheet button on the command palette over on the right hand side of the screen to do this A window will pop up prompting you for the component name Make sure you append the directory in the box with a suitable name for your new circuit such as 19 username ele202 lab5 part1 Click on OK and a new blank sheet should appear on the DA main window You are now ready to place components onto it Placing aComponent Placing a component itself has two parts 1 selecting the component to be placed and 2 actually putting it where you want it to be on the sheet When you choose a component not only are you selecting a picture or symbol of the component but more importantly you are calling up the model of the component which is used during simulation to determine the component s output values over time given its time varying input signals OK let s put an AND gate on the screen Click the Library button located on the palette A list of possible digital libraries of components will appear where the palette was Select Is_lib This library contains models for the 74LSxx series of SSI MSI digital logic This logic family was in great use a while ago and is still used for glue logic Other libraries likely to contain the TTL chips include 74LS and GLU
68. tly be learning how to estimate the currents which will flow in a circuit so that we can use the Simpson milliammeter on your workbench safely current power PMC supply power element i PUPR Figure 1 1 Basic circuit A a and circuit for measuring voltage and B current b a Panel Meters You will have noticed that the power supplies have meters which measure voltage and current These are known as panel meters and indicate the voltage at the supply terminals and the current passing through the supply They are not very accurate but are very useful in giving a rough idea of where we are when doing an experiment especially in warning us when we are exceeding some rating l V characteristic for a resistor Connect the circuit shown in Fig 1 1b above where the element is the resistor ask your lab instructor to get the proper resistor for this set of measurements Before turning on the power supply turn the control knob all the way counterclockwise so that the output voltage is zero by doing this we ensure that we will not get excessive current through the milliammeter when we turn the power on Gradually increase the voltage across the resistor and measure the voltage across it for various values of the current flowing through it Take data up to the value 50 milliamperes Whenever you take data it is good practice to take it in neat tabular form so that it is absolutely clear what measurements were being made label the columns and
69. ts for 600ns or until all possible output patterns are displayed on the trace whichever is greater Additional Note on Copying Your Mentor Graphics Files There are two main reasons why you may need to copy your Mentor Graphics files to another location The first reason was alluded to earlier If you start your design on ECL and wish to continue entering the design on ELE you will need to ftp your files from one account to another The second reason is that you will most likely be working with a partner due to the limited number of workstations available If you begin the design in your account your partner will eventually need a copy of these files for his her own use Mentor Graphics is highly particular about the directory structure of your files You can NOT simply copy files the way you normally would the following procedure must be followed in order for the copy to work 1 The first thing you must do is to pack up all of the files in such a way as to be able to correctly restore the directory structure in the new location but to have Mentor Graphics recognize the new location as a valid Mentor Graphics directory structure Fortunately we have a script file which was written by Tim Toolan our system administrator that will do this for us Type mgpack lt mg_directory gt where lt mg_directory gt refers to the Mentor Graphics directory where you have your files stored such as ab5 This command produces a file called lt mg_directo
70. u have to keep holding the probe in place The ground clip at the end of the probe has to be connected to ground If it is not long enough to reach a grounded point in your circuit then extend your circuit do not try to stretch the ground lead on the probe It will get pulled off and will have to be mended Vertical System Controls Let us put a simple signal into the vertical system of the scope Connect the BNC end of the probe to CH1 Set the selection switch on the probe to 1X Connect the other end of the probe across the output terminals of the variable voltage supply on the PS503A Remember what we said about clipping the probe on Connecting short bare wires to the output terminals of the power supply will help you attach the probe properly Set the sweep generator at 5 ms div at this setting you see a nice horizontal trace with no flicker which makes it comfortable for the eyes Set the CH1 VOLTS DIV at 1 on the 1X indicator since we are using the 1X setting on the probe it means one vertical division corresponds to one volt Set the selector switch above the knob to CH1 With the selector switch below the knob set at GND use the vertical position control knob to set the trace along the bottom dotted line of the display Now switch the selector from GND to DC and vary the output of the PS502 variable voltage supply You can see that the vertical deflection is proportional to the voltage at the CH input Use the VOLTS DIV knob to change
71. ultimeter to discover the internal connections and operation of the board Remember that one should not use an ohmmeter in a live circuit Note also that the voltmeter might give any reading between 0 volt and 5 volt when used to measure the voltage drop across a floating point and ground CMOS logic levels As you have seen in ELE201 there are only two logic levels 1 and 0 With the power supply Vpp at 5 Volts the voltage at any input or output in CMOS digital circuits will be either 5V or OV So let us agree on the convention that 5V level corresponds to logic 1 and the OV level corresponds to logic 0 This convention is called positive logic Some logic systems such as the popular PDP 11 computers back in the 1970 s actually use the negative logic convention which means that the higher voltage corresponds logic 0 and the lower logic corresponds to logic 1 But let s not confuse ourselves here We will use positive logic convention throughout the rest of this course So instead of talking about voltages in the circuit we shall talk about logic levels A two input CMOS gate has two inputs and one output The output level is a function of the two input levels IC Chips We shall be working with the following chips 14001 Quad 2 input NOR gate 14071 Quad 2 input OR gate 14011 Quad 2 input NAND gate 14077 Quad Exclusive NOR gate 14070 Quad Exclusive OR gate 14081 Quad 2 input AND gate Quad 2 input means that each chip contains four identi
72. upply must never get directly connected together Supplies or instruments which do not have a grounded terminal are called floating The same instrument may have both grounded and floating inputs or outputs For example the 5 V supply on the PS502 is grounded and the variable supply is floating Circuit If we connect an element across the power supply Fig 1 1a a current flows in the circuit Note that a closed path is necessary for current to flow In the diagram for instance the current flows from the supply to the element along the lead through the element back to the other terminal of the power supply through the supply and so round again The power supply maintains the voltage V across its terminals The element now has a voltage V across it and a current flowing through it In this situation the element gets a power P from the supply The magnitude of P is given by P Vx where P in Watt V in Volt and in Ampere Ammeter In order to measure the current in the circuit we have to cut into the circuit at A and B and insert the ammeter as shown in Fig 1 1b The voltage at the red terminal of the ammeter has to be higher than the voltage at the black terminal so that the current enters at the red terminal and leaves at the black terminal If the ammeter 4 is connected the wrong way the needle will get deflected the wrong way and get damaged Again if excessive current flows through the ammeter it will get damaged We will shor
73. ure the problem can indeed be solved by use of a state machine State the problem is in terms of logic variables and states Develop a simple block diagram 2 Detailed specifications Develop a detailed block diagram Perform function partitioning Separate the system controller from other functional units The system controller is responsible for interacting with external input output and generating all internal sequencing signals The system controller will be implemented as a state machine Identify and assign symbols to the logic variables 3 State diagram Consider the step and step timing events of the circuit and represent them by use of a state diagram You may also draw a timing diagram at this point to help you in developing the state diagram The state diagram is perhaps the most important part of the sequential circuit design Together with the detailed block diagram the state diagram defines the operation of the circuit 4 State table Chose a type of flip flop for implementation Based on the state diagram develop a truth table which show all the possible state transitions from the present state to the next state The state transitions are often controlled by the inputs to the state machine Also include the truth table for all output sequencing signals into the state table 5 Logic functions From the state table derive the logic functions for the next state decoder and the output decoded Express every output as a function of the input
74. you can also go directly to a document s Table of Contents and Index with the gray button s on the left side of the top bar The Mentor online documents have hyperlinks that look and work pretty much the same way as they do with Netscape To learn more about the capabilities of the Bold Browser look at its documentation using of course the Bold Browser itself Mentor Tools has other manuals too for example the Design Architect User s Manual for learning the capabilities of the tool after looking at the Getting Started document Also the Design Architect Reference Manual which is used for reference purposes when you can t figure out how to do something in particular Design Manager This should be the first program you start every time you work with the Mentor Graphics Tools All other tools are then invoked from the Design Manager DM including the Bold Browser To start DM first change to your lab5 directory then type dmgr at the Unix prompt The at the end of the command simply executes DM in the background thereby allowing you to use your xterm window for other purposes Once DM starts expand the window so it fills a larger area on the screen The main thing to notice about DM is the window in the upper left corner entitled Tools which contains all the tools available in the Mentor Graphics Package We will only be using two of them namely the Design Architect and QuickSim II which will be described in more detail bel

ELE 202 - Electrical, Computer & Biomedical Engineering

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ELE 202 - Electrical, Computer &amp; Biomedical Engineering

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ELE 202 - Electrical, Computer & Biomedical Engineering