Core of the Embedded System GENERAL PURPOSE & DOMAIN SPECIFIC PROCESSORS Microprocessors Microcontrollers Digital Signal Processors 2. APPLICATION SPECIFIC INTEGRATED CIRCUITS(ASIC) 3.PROGRAMMABLE LOGIC DEVICES(PLD) COMMERCIAL-OFF-THE-SHELF COMPONENTS(COTS)

MICROPROCESSORS: Has CPU Capable of performing arithmetic & logical operations Dependent unit ie requires memory, timer unit ,interrupt controller etc. MICROCONTROLLERS: Highly intergrated chip Contains its own CPU, scratchpad RAM, on chip ROM/Flash memory Has dedicated ports Independent working Cheap , cost effective and readily available.

DIGITAL SIGNAL PROCESSING: Are powerful 8/16/32 bit microprocessors For audio,video and communication applications 2 to 3 times faster from microprocessors Consists of :Program memory(rom),Data Memory (RAM),Computational Engine,I/O unit

RISC-Reduced Instruction Set Computing CISC-Complex ISC Less number of instructions Uses pipelining & increased execution speed. Orthogonal Instruction set(instruction type and the addressing mode vary independently) Operations on registers . Memory : load & store Large number of registers are available Need to write more code since instructions are simple Harvard architecture More number of instructions No instruction pipelining Non-Orthogonal Instruction set Operations on registers or memory. Limited number of registers are available Need to write less code since instructions are complex Von-Neumann Harvard architecture CPU design strategy

Von-Neumann Architecture Harvard Architecture Von-Neumann Architecture Separate buses for instruction and data fetching Easier to pipeline , high performance Comparatively high cost Program & data memory are stored at different places hence no chances of accidental corruption of program memory Single Shared buses for instruction and data fetching Low performance cheaper Program & data memory are stored in the same chip, hence their are chances of accidental corruption of program memory

ASIC An application-specific integrated circuit (ASIC) is an integrated circuit (IC) customized for a particular use, rather than intended for general-purpose use. It integrates several functions into a single chip. Takes up very small area hence helps in designing smaller system Reduced cost. NON RECURRING ENGINEERING CHARGE(NRE)

PLD A programmable logic device or PLD is an electronic component used to build reconfigurable digital circuits. Unlike a logic gate, which has a fixed function, a PLD has an undefined function at the time of manufacture. Before the PLD can be used in a circuit it must be programmed, that is, reconfigured. No NRE costs.

COTS Which is used as ‘as-is’ . They provide easy integration & inter-operability with existing systems components. Generally designed/developed around a processor. No operational & manufacturing standards. Are like proprietary products , cannot be used with some other product.

Sensors & actuators Sensors are transducers that converts one form of energy to another. Actuators convert signals to corresponding physical action. (basically Output device) 7 Segment LED display

Communication interfaces On –board communication interface External communication interface On –board communication interface: I2C BUS: bi-directional, Serial Clock & data lines (SCL: high & SDA:low) SPI (serial peripheral inteface) BUS: Master Out Slave In(MOSI), MISO,SCLK,slave select(SS) ; fully configurable

3.UART BUS(Universal Asynchronous Receiver Transmitter) Doesn’t require clock signal. Depends on pre-defined agreement Settings:baudrate,parity bits 4.I-WIRE INTERFACE: uses a single signal wire DQ. Data & signal uses the same line. Single master(reset pulse) and many slaves(presence pulse)

External communication interfaces RS-232:legacy,wired ,asynchronous serial interface. uses handshaking & control signals for data transmission USB(universal serial bus):wired high speed bus. Core group members, star topology:1 master, many slaves IrDA(Infrared):line of sight based wrireless device BT(bluetooth):low cost low power short range wireless tech, bluetooth protocol stack. Wi-Fi:networked communication devices, supports IP protocol.requires an agent:wifi router/ access point. ZigBee:low power low cost network communication protocol, low data rate, secure communication for Wireless PAN GPRS(general packet radio service):comm technique for transferring data over a mobile network. Data split into various packets.

Other components RESSET CIRCUIT: Ensures that a device is not operating at a voltage level where the device is not guaranteed to operate. It brings the internal registers to a known state. BROWN-OUT PROTECTION CIRCUIT: Prevents the processor/controller from unexpected program execution when the voltage falls below a specified voltage. Esp. for battery powered devices.

OSCILLATOR UNIT REAL TIME CLOCK WATCHDOG TIMER Ms.Sarita Balakrishnan Assistant Professor SIES ,Sion(West).