1. 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)

2. 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.

3. 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

4. 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

5. 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

6. 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)

7. 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.

8. 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.

9. 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

10. 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

11. 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)

12. 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.

13. 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.

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