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By Fateen Mubarak EMBEDDED SYSTEMS DESIGN (EE 4314) 1

Embedded Systems Design(EE-4314)

Fateen MubarakLecture # 7

18 th September 2013

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Embedded design considerations

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Embedded design considerations

I wish to have the best embedded system, but I could acceptthe right solution.

Success

Time-to-Market

Budget/Cost($$)

TeamCapability

Market Need

SystemPerformance

Interface/Communication

Power

Life-cycle/Reliability

Regulations

SensorSoftwareMemory

Control

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Interesting survey results about embedded design

These results are based on a 2011 study of the embedded space by UBMElectronics in conjunction with EE Times and Embedded System Design.

An embedded design team has 13.5 members on average62% software, remaining hardware.

Looking at embedded projects43% focused on brand new developments.

57% are upgrades to existing embedded systems.

Projects take 12 months to complete on average.57% finished late or were cancelled.

Design teams reused 87% of existing code.

[Source] Sanjay Challa, How FPGAs, multicore CPUs, and graphical programming are changingembedded design, EE Times 5/9/2012

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By Fateen Mubarak EMBEDDED SYSTEMS DESIGN (EE 4314) 5

Communication Protocols

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Why communication protocol? Embedded System as stand alone Systems:

exchange of data between sensors or other passive devices. Embedded System as a part of system:

exchange of data between other systems and sensors as a partof complete System.

Therefore a communication protocol in an EmbeddedSystem is used:

To guarantee that the timing requirements of all tasks are met. To guarantee that there is no loss of information.

To guarantee that the receiver and sender have the sameinformation.

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By Fateen Mubarak EMBEDDED SYSTEMS DESIGN (EE 4314) 7

What is a communication protocol? Definition:

A set of formal rules describing how toexchange data

Levels of Protocols: Low Level Interface

(Electrical Characteristics, Physical interface etc)

High Level Interface (Bit formatting, data encoding, syntax, special bits,

timing etc)

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Types of communication protocol? Communication Protocol Types:

Wired Communication Protocols: Serial

RS-232 RS-485

I2C SPI CAN USB MIL-STD 1553 MIL-STD 429 MIL-STD 1773

Wireless Communication Protocols: IR RF

Parallel 8 Bit bus Interface 16 Bit bus Interface 32 Bit bus Interface 64 Bit bus Interfaceetc

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By Fateen Mubarak EMBEDDED SYSTEMS DESIGN (EE 4314) 9

UART

UART: Universal Asynchronous Receiver Transmitter Takes parallel data and transmits serially Receives serial data and converts to parallel

Parity : extra bit for simple error checking Even and Odd Parity

Start bit, stop bit Baud rate

signal changes per second bit rate usually higher

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UART structure It contains

Configuration Registers Two independently operating processors Transmit Buffer and Receive Buffer Parity

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UART The transmission rate at which the bits are

sent and received is known as Baud Rate 115200 b/sec 1 bit = 8.68 usec

Total Number of Bits in a packet (Protocol) 1 start bit, 8 data bits , 1 parity bit ,1/2 stop bit

Stop Bit is important