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Chapter 8

Chapter 8. Microcomputers. Micro computer Micro controller. What’s the difference?. What is a microcontroller? What are some common applications of these? A microcontroller is a simple computer on a single silicon chip that cost only a few dollars.

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Chapter 8

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  1. Chapter 8 Microcomputers

  2. Microcomputer Microcontroller What’s the difference?

  3. What is a microcontroller? What are some common applications of these? A microcontroller is a simple computer on a single silicon chip that cost only a few dollars. They are useful in washing machines, toasters, and cars. Homework 7

  4. All modern automobiles contain at least one microcontroller, and can have as many as six or seven. The engine is controlled by a microcontroller, as are the anti-lock brakes, the cruise control and so on. Microcontrollers in Cars and Trucks?

  5. Any device that has a remote control almost certainly contains a microcontroller: TVs, VCRs and high-end stereo systems all fall into this category. Digital cameras, cell phones, camcorders, answering machines, laser printers, telephones (the ones with caller ID, 20-number memory, etc.), pagers, and feature-laden refrigerators, dishwashers, washers and dryers. Basically, any product or device that interacts with its user has a microcontroller buried inside. Interesting…

  6. PIC Microcontroller • We will use the 16F84A microcontroller made by Microchip for the team project. Use the Internet to research these chips.

  7. Acronyms • IC • RAM • ROM • PROM • EPROM • EEPROM • PIC

  8. IC – Integrated Circuits

  9. RAM – Random Access Memory

  10. ROM – Read Only Memory ROM cannot be modified (at least not very quickly or easily),

  11. ROM – Read Only Memory ROM cannot be modified (at least not very quickly or easily),

  12. PROM – Programmable Read Only Memory setting of each bit is locked by a fuse

  13. Google “PROM Memory”

  14. EPROM – Erasable Programmable Read Only Memory

  15. EEPROM – Electronically Erasable Programmable Read Only Memory

  16. EEPROM – Electronically Erasable Programmable Read Only Memory

  17. PIC – Programmable Integrated Circuits PIC PIC

  18. The SFA Rover Team Project

  19. The Vehicle Course 6-feet 50-feet

  20. The Vehicle Course 6-feet 50-feet Extra Credit

  21. Scoring D = Distance traveled in feet in 10 minutes (the maximum distance is 50-feet) R = 15 if the vehicle successfully demonstrates avoiding an obstacle on the right and 0 if it is not demonstrated L = 15 if the vehicle successfully demonstrates avoiding an obstacle on the left and 0 if it is not demonstrated T = -10 each time the vehicle is touched by a team member during the course Grade = T + L + R + D × 70/(50ft) Bonus: For each extra left or right obstacle avoided, 2 points of extra credit will be earned for each member of the team. A maximum of 20 extra points can be earned in this manner.

  22. SFA Rover Circuit Diagram Left Button Right Button 9-Volt Battery PIC Microcontroller Voltage Regulator H-Bridge Left Motor Right Motor

  23. Key Concepts Note that the parts used in the team project are discussed in your text book. • Chapter 7 - Logic Circuits • Chapter 8 - Microcomputers • Chapter 10 - Diodes (Voltage Regulator) • Chapter 12 - Transistors (H-Bridge) • Chapter 16 - DC Machines (Motors)

  24. Key Concepts Other key ideas used in this team project include: • Battery Power Management • Torque • Friction • Gearboxes We will now design circuits that will be used in lab next week.

  25. Chapter 10 Diodes

  26. Semiconductors • Germanium • 32 protons • Silicon • 14 protons • Most commonly used

  27. Atomic Physics • How many electrons can be in the ground state of an atom? • Answer: 2 (s level) • ...in the first excited state? • Answer: 8 (s and p levels) • …in the second excited state? • Answer: 8 (s and p levels)

  28. Valence Electrons • Valence electrons are electrons in the outermost shell of the atom that can participate in forming chemical bonds with other atoms. • How many valence electrons does Silicon have? • Answer: 4

  29. How many electrons are needed to fill the outermost energy level of Silicon? • Answer: 4 • 2-D representation of Silicon Crystal • How many valence electrons does Phosphorus (15P) and Aluminum (13Al) have? • Answers: 5 and 3

  30. Diodes • Conduct electricity in one direction • Two terminal devices • anode and cathode • Primarily made of silicon

  31. DopingThe adding of impurities • n-type crystal • e.g. Silicon doped with Phosphorous • negative charge carriers • electrons • p-type crystal • e.g. Silicon doped with Aluminum • positive charge carriers • vacancy or hole

  32. Diodes Circuit Symbol p-type n-type

  33. Flapper Valve Analogy Flapper Valve Analogy

  34. Diode Characteristics • Forward-Bias Condition • Good Conductor • Reverse-Bias Condition • High Resistance • I versus V Plot • Ideal Diode and Real Diode • “Knee” and Breakdown Voltage • Three Regions

  35. Shockley Equation • Shockley Equation on Excel • Common LED have a maximum recommended current of 20mA. • What resistor value is needed in series with an LED and a 5-Volt power supply so that the LED does not burn up? • Answer: _______ or ________

  36. What does the circuit symbol for an LED look like?

  37. Diode Circuits • rec·ti·fi·erPronunciation: 'rek-t&-"fI(-&)rFunction: nounDate: 1611: one that rectifies; specifically: a device for converting alternating current into direct current • Half-Wave Rectifier • Full-Wave Rectifier • Bridge Rectifier

  38. Smoothing Capacitors • Ripple Voltage (Vr) • DC Component (VDC) • Ripple Factor

  39. Concept Test • Is a high or low value for the ripple voltage DV desirable? • Answer: Low • What are three ways to achieve low ripple voltages? • Answers: • Low Current • High Frequency • High Capacitance

  40. Zener Diodes • Zener Diodes are intended to operate in the breakdown region. • Manufacturers set the breakdown voltage by modifying the doping. • Zener diodes can make good voltage regulators. • Circuit Symbol • Clarence Zener once visited SFA.

  41. What is a Zener diode? How do the circuit symbols for a diode and a Zener diode differ? • Zener diodes are intended to operate in the breakdown region -usually as voltage regulators. • Manufacturers set the breakdown voltage by careful doping.

  42. How do you convert AC to DC? AC Input Diode Rectifier Smoothing Capacitor Voltage Regulators remove the ripple. DC Output Voltage Regulator

  43. Concept Question • What components to you need to convert a 110-Volt AC signal to a 9-Volt DC signal? • Answers: • Transformer – to step down the voltage • Diodes – to rectify the waveform (make +) • Capacitor – to smooth the rectified waveform • Voltage Regulator – to remove the ripple • Note that the device connected to this 9-Volt power supply acts as a resistor. • For this reason the device is sometimes called the “load” or “load resistance”.

  44. Example Questions 10.32, 35 Homework Questions? 10.55, 56, 57, 35

  45. What is an ideal diode? • An ideal diode is a perfect conductor with zero voltage drop in the forward bias direction… • …and a perfect insulator in the reverse bias direction.

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