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Examples of embedded systemKeyboardPrinterMp3 Music playerVideo game playerDomestic appliancesA.C.calculatorMobile phone units

Embedded system embedded system Microcontroller

8051 microcontroller PIC AVR ARM

PIC-Peripheral Interface controllerAVR-advance virtual RISCARM-Advance Risk Machine

MicrocontrollerA smaller computerOn-chip RAM,ROM,I/O portsExample: -Motorolas 6811,Intel 8051,PIC

Microprocessors Microcontrollers1It is only a general purpose computer CPUIt is a micro computer itself2Memory, I/O ports, timers, interrupts are not available inside the chipAll are integrated inside the microcontroller chip3Systems become bulkier and expensive.Make the system simple, economic and compact4Not capable for handling Boolean functionsHandling Boolean functions5Higher accessing time requiredLow accessing time6Very few pins are programmableMost of the pins are programmable7Widely Used in modern PC and laptopswidely in small control systemsE.g.INTEL 8086,INTEL Pentium seriesINTEL8051,89960,PIC16F877

light-emitting diode

A light-emitting diode (LED) is a semiconductor device (LED chip) that emits visible light when an electric current passes through it - essentially it converts eletricity into light. When one or more LED's are combined with an electrical driver and placed in a housing unit, you have a complete LED system. LEDs have many advantages over incandescent light sources including: lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. Light-emitting diodes are now used in applications as : general lighting traffic signals, and camera flashes.

Identification of led

Interfacing with microcontroller 8051

Seven-Segment DisplayA seven-segment display (SSD), or seven-segment indicator, is a form of electronic display device for displaying decimal numbers(0-9),alphabets .Seven-segment displays are widely used in digital clocks, electronic meters, and other electronic devices for displaying numerical information.

Seven-Segment DisplayIn a simple LED package, typically all of the cathodes (negative terminals) or all of the anodes (positive terminals) of the segment LEDs are connected and brought out to a common pin; this is referred to as a "common cathode" or "common anode" device.

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Seven-Segment DisplayThere are two type of 7-segment lcd digital display:Common cathode display(ccd): All cathodes are common and ground is being provided.Common anode display(ccd): All anodes are common and Vcc is being provided.

CADCCDON=0ON=1OFF=1OFF=0

Seven-Segment Display

Seven-segment interfacing

Liquid crystal display(lcd) Lcd contents :HD44780LCDCheap and easy way to display text no. ,letters and fixed symbols.Various configuration: 1line,2line and 4line. Data lines(DB7-BD0) used to transfer data and commands. Types:Normal lcd example: watches

Liquid crystal display(lcd)Graphical lcd Example: laptop, PC lcd.Types of Memories: DDRAM: Data Display RAM store data represented in 8-bit character code.CGRAM(character generator RAM):In CGRAM ,the user can rewrite character pattern by program.In lcd instruction register is used to send command to lcd. example: lcd clear commandData register is used for storing data which is to be displayed on lcd.

Liquid crystal display(lcd)

Pin Description of LCDPin no.Symbol details1GNDGround2VccSupply voltage +5v3VEEContrast adjust 4Rs0 = control i/p5R/W1-= data o/pRead /write6Eenable7-14D0 D7data15VB1Backlight +5V16vb2Backlight Ground

Lcd interfacing with 8051

IR remote control systemIC used:555 ICAlso called timer ICTSOP(thin small outline package):work with IR in Rx circuitPin diagram:

IR remote control systemCkt. Diagram:

DTMF based home controllerDTMF: Dual Tone Multiple FrequencyUsed for mobile phoneDeveloped in Bell lab in 1963IC used :MT 8870 IC

RF ModuleRF module ,as the name suggest ,operate on radio frequency.Frequency Range:-30KHz- 300KHzIn RF system, the digital data is represented as variation in the amplitude of carrier wave .This kind of modulation is ASK.RF Tx is better than IR Tx. RF module is the combination of an RF transmitter and RF receiver. RF Tx/Rx pair operate at 434 MHz frequency. Data Tx rate:-1Kbps -10KbpsRF module provide wireless communication

RF ModuleRF Tx RF Rx

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Relay A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism mechanically.A type of relay that can handle the high power required to directly control an electric motor or other loads is called a contactor.

RelayOperating voltage:- +5v to +12vApplication: Telephone Exchanges, Digital computer,Automation systemBuffer IC: ULN 2803 or Relay Driver IC

Types of RelaySingle pole single through(SPST)Single pole double through(SPDT)Double pole single through (DPST)Single pole double through(DPDT)