ENG3640 Review and Exam Question1 ENG3640 Microcomputer Interfacing Review & Final Exam Structure

ENG3640 Review and Exam Question2 Topics  Programming  I/O Interfacing  Interfacing Devices  Data Acquisition Systems  Timing Generation  Serial Communication  Busses  Transmission Lines  Memory Interfacing

ENG3640 Review and Exam Question3 Course Objectives Achieves the following goals: 1. Learn about Microcontroller architecture 2. Understand Software Development 3. Program in assembly language 4. Interrupts, DMA, Polling 5. Learn Basic I/O techniques (Parallel, Serial) 6. Learn Serial communication Systems 7. Understand functionality of busses 8. Understand Data Acquisition Systems 9. Learn about Memory Technology and Interfacing

ENG3640 Review and Exam Question4 Q1. Software Development Problem Statement Design Stage Effective Data Structure Modular Design (Procedures) Implementation Instruction Set Addressing Modes Assembly Format Testing Directives

ENG3640 Review and Exam Question5 Analysis

ENG3640 Review and Exam Question6 Software Development

ENG3640 Review and Exam Question7 Program Development

ENG3640 Review and Exam Question8 Q2. General Interfacing  Switch Debouncing  Keyboard Interfacing  LCD +5V A

ENG3640 Review and Exam Question99 Hardware Debouncing: Schmitt Trigger  A Schmitt trigger is a special circuit that uses feedback internally to shift the switching threshold depending on whether the input is changing from low to high or high to low.  The difference between V T+ and V T- is called hysteresis.  A 74LS14 Schmitt Trigger inverter can be used to debounce a switch. V IN V OUT V T+ V T- 5.0 Example: 74LS14

ENG3640 Review and Exam Question10 Liquid Crystal Displays: Operation  An LCD display requires an alternating excitation wave applied to selected electrodes to change selected areas.  A constant (DC) excitation signal will polarize and destroy the crystal. 60 Hz Oscillator Control BP FP XOR V LCD Front Plane Liquid Crystal Material Back Plane

ENG3640 Review and Exam Question11 I/O Interfacing

ENG3640 Review and Exam Question12 General Interfacing  Any MCU would communicate with peripherals through I/O ports.  Types of data 1.Numeric/Alphanumeric 2.Control/Status Information  Basic I/O Transfer alternatives can be classified as 1.MCU Initiated 2.I/O Device Initiated MCU Initiated Device Initiated Unconditional Transfer Polling (Gadfly) Interrupts Direct Memory Access Periodic Polling

ENG3640 Review and Exam Question13 Synchronization Techniques

ENG3640 Review and Exam Question14 Q3. Timer Module  Input Capture: “captures the time at which an external event occurs”. Can be used to: 1. Generate interrupts and 2. Measure period or pulse width  Output Compare: “can generate a periodic pulse with a programmable polarity, duration, and frequency”. Can be used to: 1. Create periodic interrupts, 2. Generate: Pulses, Square waves 3. Measure frequency

ENG3640 Review and Exam Question15 General Understanding of TIM

ENG3640 Review and Exam Question16 Q4. DAQ Real World Measurand Transducer (sensors) Analog Mux Signal Conditioning Sample and Hold Circuit A/D Conv MCU D/A Conv Actuator

ENG3640 Review and Exam Question17 Analysis or Design of Signal Conditioning

ENG3640 Review and Exam Question18 Data Acquisition Systems

ENG3640 Review and Exam Question19 Q5. DACs or ADCs  A/D converters are classified according to several characteristics  Resolution (number of bits) typically 8 bits to 24 bits  Speed (number of samples per second) – several samples/sec to several billion samples/sec  Accuracy – how much error there is in the conversion  Classification 1. Staircase ADC 2. Tracking ADC 3. Successive Approximation Converters 4. Flash A/D Converters 5. Integrating A/D Converters

ENG3640 Review and Exam Question20 Important Circuits in DAS

ENG3640 Review and Exam Question21 Q6. Serial and Parallel Communications TransmitterReceiver CLK

ENG3640 Review and Exam Question22 Understanding of the Technology

ENG3640 Review and Exam Question23 Serial Communication Systems

ENG3640 Review and Exam Question24 Bus Protocols  Protocol refers to the set of rules agreed upon by both the bus master and bus slave  Synchronous bus ­ transfers occur in relation to successive edges of a clock  Asynchronous bus ­ transfers bear no particular timing relationship  Semi ­ synchronous bus ­ Operations/control initiate asynchronously, but data transfer occurs synchronously CPU Device 1Device 2Device 3 Bus

ENG3640 Review and Exam Question 25 ENG3640 Fall Transmission Line Models  When can the R and G terms be ignored in the Z 0 ? w  As w increases, the impact of R and G decreases. w  When the frequency increases above 100 kHz, the terms multiplied by w start to dominate.

ENG3640 Review and Exam Question26 Reflections on the Bus  To reduce reflections, the ends of a transmission line should be terminated by connecting a resistor equal to Z 0 across the line  Connecting a resistor between the bus and V CC will pullup the lower logic level and reduce noise immunity  Classic Solution: connect two resistors to the bus one to the ground and one to V CC  R1//R2 = Z 0 RTRT VTVT R T = R1//R2 = Z 0 Bus

ENG3640 Review and Exam Question27 Lattice Diagram Analysis – Key Concepts Diagram shows the boundaries (x =0 and x=l) and the reflection coefficients Time (in T) axis shown vertically Calculate voltage amplitude for each successive reflected wave Total voltage at any point is the sum of all the waves that have reached that point Vs Rs Zo V(source) V(load) TD = Nps 0 Vs Rt The lattice diagram is a tool/technique to simplify the accounting of reflections and waveforms TimeV(source) V(load) a source  load  b A c A’ B’ d B e 0 Nps 2Nps 3Nps 4Nps 5Nps

ENG3640 Review and Exam Question28ENG3640 Fall What Should Designer do?  Practically there are several ways to mitigate the negative impact of reflections: 1. Wait long enough after each signal transition for the reflection on the line to die out ( OK for low speed but not high speed systems) 2. Decrease the frequency of the system so that reflections reach steady state before another signal is driven onto the line (Low Speed Sys!) 3. Shorten the Bus or (PCB trace) so that reflections will reach steady state in a shorter time (not practical or sometimes impossible!) 4. Terminate the transmission line with an impedance equal to the characteristic impedance of the line: Use a matched termination at far end. Thereby producing no reflections on the line Use a matched termination at source end absorbing the wave reflected from the far end.

ENG3640 Review and Exam Question29 Why, How to solve Reflections

ENG3640 Review and Exam Question30 Q7. Memory

ENG3640 Review and Exam Question31 Understanding the Principle of Operation

ENG3640 Review and Exam Question32 Address Decoding

ENG3640 Review and Exam Question33

ENG3640 Review and Exam Question34