1. ECA1212 Introduction to Electrical & Electronics Engineering Chapter 10: Digital Systems by Muhazam Mustapha, December 2011

2. Learning Outcome Understand the basics of computer system Be able to explain the circuits of electronics instrumentation By the end of this chapter students are expected to:

3. Chapter Content Computer System Architecture Instrumentation

4. Computer System Architecture CO3

5. Microcomputers Microcomputers are the results of the integration of a very large number of digital electronics components on an integrated circuit to perform intelligent and systematic tasks through the use of programs They can be categorized into 2 groups: –Microprocessor: more for general purpose use e.g.: Intel Pentium, i3, AMD Athlon, Sempron, etc –Microcontroller: for a specific use e.g.: Intel 8051, PIC16x84, Atmel AVR, etc CO3

6. Microprocessors Since it is for a general purpose computing, microprocessor has the following generic architecture: CO3 Text book Figure 14.30

7. Microprocessors In the previous slide, the input sensors are the common devices like keyboard, mouse, touchpad, cameras, etc While the outputs are also common like VGA screen, speaker, disk drives, etc CO3

8. Microcontrollers Since it is for a specific purpose, microcontroller has the following generic architecture: CO3 Text book Figure 14.33 (a)

9. Microcontrollers In the previous slide, the input sensors and output actuators are for that specific task meant for the system For example, if the system is for temperature controller, the input must include a temperature sensor, and the actuator or output must include some device to indicate the temperature value or to activate something to lower or higher the temperature CO3

10. Components Based on the previous slides, the core components of a computing system can be listed as follows: –Central Processing Unit (CPU) –Memory –Program CO3

11. Central Processing Unit CPU is the heart of a microprocessor It performs the computation that is kept in the memory as program code and then transfer the input or output to the outside system as necessary To perform the task it uses a collection of registers, mostly accumulator, to compute basic Boolean processing like AND -ing, OR -ing, rotate, shift, as well as the arithmetic ones like, adding, subtracting, etc CO3

12. Memory Normally called RAM (random access memory) Memory is an electronic device that keeps Boolean values: –as flip-flops: SRAM (static) –as charge on capacitor: DRAM (dynamic) Mass storage is also a kind of memory but it is significantly larger than the memory and non- volatile (keeps value even though when powered off): –harddisk, thumb drive CO3

13. Program Computer program is a sequence of 1-s and 0-s kept in memory to instruction the computer about what to do Two types of programs: –High-level: coded using human friendly words – C/C++, Java, C#, etc –Low-level: coded using mnemonics or code that is more computer friendly – assembly language CO3

14. Assembly Language It is a low level programming language to program microprocessor using mnemonics Operation code (opcode) is the sequence of 1-s and 0-s that correspond to a specific instruction Each instruction in assembly language then has a 1-to-1 mapping to opcode Look at one assembly language example in text book Example 14.6 CO3

15. Assembly Language Another example: CO3 MOV A, H40; load 40 hex to accumulator MOV B, [H0032]; load reg B with content from memory addr 32 hex SUB A, B; JZ Error;

16. Instrumentation CO3

17. Measurement System Measurement system can be built using a microcontroller system with transducers as inputs –nowadays some system are built on general purpose microprocessors Transducers are devices that convert non- electrical energy into electrical energy (signals) – normally in analog form The signal has to be converted to digital first so that is can be used in computing systems CO3

18. Measurement System CO3 Text book Figure 15.1 Transducer Analog Digital

19. Measurement Quality Accuracy – closeness to the true value Precision – no. significant digits in the measure Resolution – smallest measurable increment Error – difference from the true value Linearity – conformity to straight line graph if we plot a graph of the non-electrical energy vs the corresponding electrical signal Span – range of linearity Range – high and low limits of measure CO3 Text book page 761

20. Measurement Devices Text book Table 15.1 page 762 list out all measurement devices for mechanical and civil engineering that it covers For your class we will cover briefly all in pages 761 – 765 Read those pages for your examination CO3

21. Mechanical Measures Absolute position: change in resistance, Wheatstone bridge Displacement & velocity: magnetic effect Acceleration & jerk: optical signal, image processing and piezoelectric material Force, torque & pressure: piezoelectric, load cell, diaphragm, strain gauge CO3

22. Fluid Measures Differential pressure: Turbine flow meter: CO3 Text book Figure 15.2 (a) Text book Figure 15.2 (c)

23. Fluid Measures Hot-wire anemometer: –a resistor that is a part of a Wheatstone bridge is place in flow tube –all resistors heat up due to the electric current, but the one in the fluid flow will cool down and causes its resistance to get out of balanced with the rest, and thus disrupting the balanced voltage on the bridge CO3 Text book Figure 15.2 (b)

24. Temperature Measures Thermocouple: –built based on the physical property that 2 different touching metals will generate potential difference that also changes due to temperature CO3 Thermistors: –built based on the physical property that metal changes resistance due to temperature Text book Figure 15.3 Text book Figure 15.4