Digital Electronics Principles Applications Fifth Edition Roger L

CHAPTER 12 PREVIEW • Elements of a System • Computer Organization • Computer Peripheral

ELEMENTS OF A SYSTEM Control Input Storage Processing Storage Output

COMPUTER ORGANIZATION CLASSICAL Control Input Memory Arithmetic and Logic Output

COMPUTER PERIPHERAL DEVICES • Keyboard • Mouse • Joystick • Paddles • Graphics tablet

Microcomputer system block diagram The address bus is unidirectional Input ports MPU The data

IN Reading input data Input ports 1. The MPU places an input address on

Writing output data Input ports 1. The MPU places an output address on the

Hours Minutes Seconds Decoder/driver 1 ppm 1 pph Mod 12 counter Mod 60 counter

MULTIPLEXED DISPLAYS 8 4 2 1 a b BCD- c 7 -seg d driver

A basic digital frequency counter Start/stop f. X Counters/decoders/drivers Start/stop 1 second f. X

SERIAL/PARALLEL DATA CONVERSION Shift registers can be used to convert from serial-to-parallel or the

UART A UART receives bytes from the data bus and transmits them one bit

Here, the UART assembles bits from the serial port and places them on the

DIGITAL TIMER Clock (time base) Input controls Self-stopping Down counter Latch/Decoder Driver Magnitude comparator

DIGITAL DICE GAMES Roll Dice Clock Counter Mod-6 Decoder/ Driver Clock Counter Mod-6 Logic

DIGITAL ROULETTE GAME Audio Amplifier +5 V Power-up Initializing Circuit Spin Wheel input Voltage

PROGRAMMABLE LOGIC CONTROLLERS • PLCs are heavy-duty computer systems used for machine control. •

MICROCONTROLLERS • A microcontroller is considered a “computer on a chip. ” • A

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CHAPTER 12 PREVIEW • Elements of a System • Computer Organization • Computer Peripheral Devices • MPU Based System • Digital Clock • Multiplexing Displays • Simplified Frequency Counter • Serial/Parallel Data Transmission • Digital Timer • Digital Games (Dice and Roulette) • Programmable Logic Controller • Microcontrollers

ELEMENTS OF A SYSTEM Control Input Storage Processing Storage Output

COMPUTER ORGANIZATION CLASSICAL Control Input Memory Arithmetic and Logic Output

COMPUTER PERIPHERAL DEVICES • Keyboard • Mouse • Joystick • Paddles • Graphics tablet • Microphone • Light pen • Scanner • Bar code reader • Strip reader • Various Sensors • Modem • Fax Input/Output Input CPU and Internal Memory Output Storage • Floppy disk drive • Hard disk drive • Optical disk drive • Tape unit • Monitor (CRT or LCD) • Television • Printer • Speaker • Plotter

Microcomputer system block diagram The address bus is unidirectional Input ports MPU The data bus is bidirectional ROM The control bus is unidirectional RAM Output ports The Theinput RAM output ROM ports contains connect programs to devices data and such permanent (and such asprograms) as keyboards printers data The MPU istemporary thetoheart of the system

IN Reading input data Input ports 1. The MPU places an input address on the bus MPU 2. The MPU asserts a READ signal on the control bus ROM 3. The addressed port puts its data on the bus RAM 4. The data is stored in the MPU Output ports

Writing output data Input ports 1. The MPU places an output address on the bus MPU 2. The MPU asserts a WRITE signal on the control bus ROM 3. The MPU places the data on the bus RAM 4. The data is written to the output port Output ports OUT

Hours Minutes Seconds Decoder/driver 1 ppm 1 pph Mod 12 counter Mod 60 counter 1 Hz DIGITAL CLOCK 60 Hz 1 pps 60

MULTIPLEXED DISPLAYS 8 4 2 1 a b BCD- c 7 -seg d driver e f g Digit drivers

A basic digital frequency counter Start/stop f. X Counters/decoders/drivers Start/stop 1 second f. X 11 cycles are counted (f. X = 11 Hz)

SERIAL/PARALLEL DATA CONVERSION Shift registers can be used to convert from serial-to-parallel or the reverse from parallel-to-serial. Parallel out Serial in in Serial 11 00 11 11 Parallel in in Serial out

UART A UART receives bytes from the data bus and transmits them one bit at a time. Receiver RS 232 Driver Transmitter Control Start Stop Bit 64321 bit Bit 750 To modem Serial data transmission is relatively slow!

Here, the UART assembles bits from the serial port and places them on the data bus one byte at a time. 01101110 UART Receiver RS 232 to Logic Level Transmitter From modem Control Parallel data transmission is relatively fast!

DIGITAL TIMER Clock (time base) Input controls Self-stopping Down counter Latch/Decoder Driver Magnitude comparator Alarm

DIGITAL DICE GAMES Roll Dice Clock Counter Mod-6 Decoder/ Driver Clock Counter Mod-6 Logic Block +5 V Roll Dice +5 V

DIGITAL ROULETTE GAME Audio Amplifier +5 V Power-up Initializing Circuit Spin Wheel input Voltage Controlled Oscillator (VCO) Ring Counter (shift register) Simulated Roulette Display

PROGRAMMABLE LOGIC CONTROLLERS • PLCs are heavy-duty computer systems used for machine control. • PLCs must be rugged to withstand the rigors of a chemical, warehouse/storage, or assembly line environment. • PLCs use MODULAR organization. Programming Module • Input Sensors - pressure - mechanical - optical • A/D converters Memory Input Module Processing Module CPU Power Supply Output Module • Motors • Solenoids • Pneumatic devices • D/A converters

MICROCONTROLLERS • A microcontroller is considered a “computer on a chip. ” • A microcontroller IC contains a CPU, RAM, ROM or EEPROM, a clock, and input/output capabilities. • Microcontrollers are: • Very inexpensive • Commonly preprogrammed and embedded in products • Commonly used to perform control functions • Manufactured in huge quantities • NOT used as the CPU in general purpose computers • Microcontroller-based systems have much less semiconductor memory (RAM, EEPROM), cost less, use less printed circuit board space, and perform fewer commands than microprocessor based systems.