Embedded system and development

Embedded system and Development Rajani Bhandari Senior Project Manager HCL Technologies

2 Topics Introduction to Embedded systems How embedded is different from PC Design constraints in embedded software Examples of Embedded applications Software development cycle in embedded applications Architecture of embedded applications. Development Guidelines

3 Introduction to Embedded systems

4 Introduction of Embedded system  An embedded system is a combination of computer hardware and software accomplished with additional mechanical or other parts designed to perform a  Embedded software is used in real life like cell phone, pager, digital camera, portable video games, Calculators, oven, washing machine etc.  : :Embedded systems often must cost just a few dollars, must be sized to fit on a single chip, must perform fast enough to process data in real-time, and must consume minimum power to extend battery life. High user expectations in terms of performance Specific Function In every electronic device Limited Resources

5 Connect via peripherals  Embedded Systems talk with the outside world via peripherals, such as:  Serial Communication Interfaces (SCI): RS-232, RS-422, RS-485 etc.  Universal Serial Bus (USB)  Multi Media Cards (SD Cards, Compact Flash etc.)  Networks: Ethernet, Lon Works, etc.  Analog to Digital/Digital to Analog (ADC/DAC)

Examples In Your Daily Life  …wake up …  …have breakfast …  …set home safety system …  …get into your car …  …on your way to your office… 6

Examples In Your Daily Life (cont’)  …in Your office… 7

Examples In Your Daily Life (cont’)  …Back Home … 8

9 9 A “short list” of embedded systems And the list goes on and on Anti-lock brakes Auto-focus cameras Automatic teller machines Automatic toll systems Automatic transmission Avionic systems Battery chargers Camcorders Cell phones Cell-phone base stations Cordless phones Cruise control Curbside check-in systems Digital cameras Disk drives Electronic card readers Electronic instruments Electronic toys/games Factory control Fax machines Fingerprint identifiers Home security systems Life-support systems Medical testing systems Modems MPEG decoders Network cards Network switches/routers On-board navigation Pagers Photocopiers Point-of-sale systems Portable video games Printers Satellite phones Scanners Smart ovens/dishwashers Speech recognizers Stereo systems Teleconferencing systems Televisions Temperature controllers Theft tracking systems TV set-top boxes VCR’s, DVD players Video game consoles Video phones Washers and dryers

11 Difference - Embedded and PC  An embedded system have defined process and function whereas PC is generic  Computer system can be manufactured with general requirement and the manufacturer does not know what the customer will do, while embedded system is Application Specific .  Numerous embedded system make up the computer  Tightly constrained: Embedded system design is tightly constraint. Important factors to be considered are as cost, size, performance, and power.  Reactive and real-time:  Continually reacts to changes in the system’s environment.  Must compute certain results in real-time without delay

Difference - Embedded and PC App- Coding 12  Embedded  Closer to the Hardware  Use native data types  Fewer System Resources  No Operating System  More efficient algorithms  Higher frequency = higher power  PC Application  Abstracted Hardware  Plenty of Resources  Has an Operating System

Embedded vs PC App - Testing Embedded  Debugging is very difficult  Emulators or simulators are required at the time of development  Usually a simple interface  Often involves extra hardware PC Application  Usually simple to get a basic debug output  Can be very sophisticated testing

Design Challenges 15 Cost Unit Cost- Cost of manufacturing each unit NON recurring Engg Cost: Monetary cost of designing the system The physical space required by the system and measured in bytes for software and gates for hardware. Execution cost The amount of power consumed which determines life time of battery. Maximum Source of power : Antennas – Bluetooth, Wi-Fi, RF . Digital displays Time-to market constraint. Hardware and software development goes in parallel Missing this window – significant loss Size Performance Power Time Line Flexiblity Change functionality without heavy NRE cost. Code should be maintainable

Design Metrics 16 SizePerformance Power NRE cost Improving one often leads to a degradation in another

Examples of embedded system 17 Car cruise controllers reacts to brake sensor and speed It Compute acceleration and deceleration System Failure Delayed computation

Mobile evolution – impact on design matrices 18 1980 analog cellular technology Digital Mobile Communication 1990 Wide Band Mobile Communication 2000 Broadband Mobile Communication 2010 Factors Affected Cost Design Complexity Size Performance Power Consumption

Digital camera- An embedded system example 19 Microcontroller CCD preprocessor Pixel coprocessor A2D D2A JPEG codec DMA controller Memory controller ISA bus interface UART LCD ctrl Display ctrl Multiplier/Accum Digital camera chip lens CCD

Time to Market- Design challenge 20 Revenues($) Time (months) Market window: Period during which the product would have highest sales Average time-to-market constraint is about 8 months. Delays can be costly.

Design Challenge 21 After decision of mass production of embedded system and a small bug found at that time may be very expensive. Even a 1 day delay can cost equivalent ……… Any Guesses??

22 Software Development Life cycle

Embedded system Life Cycle 23 Development of Hardware and software goes in parallel which is a major challenge.

24 Architecture of embedded application

25 Architecture of embedded system Application Software Operating System Hardware

Guidelines for embedded application development Power:  Optimal Power usage  Transferring data on Air Reset Device  Design for the restoration of configuration 28 Memory Guidelines Data Type Life time of variable Memory allocation on heap or stack. Memory should be freed if not required Stateless components Logging and Instrumentation User Interface Simple UI Hour glass as visual indicator for blocking operation Resolution and LCD size Design for usability by supporting for touch, stylus driven, 5- way Do not update ui frequently

Key rules for best coding 29 Maintainability Reliability Efficiency

Maintenance problems  Unstructured code  Insufficient domain knowledge  Insufficient documentation 30

Efficiency  Optimal Utilization of Resources  Design and architecture of software  Memory management 31

32 Coding standards Readability of code  Size of Function  Variable naming  Code Commenting  Long methods  Private, public or local variable naming rule  Formatting and indentation Complexity of code  Multiple return statement  Nested loop or conditions Uninitialized variables Duplicate code prone to errors Avoid Hard Coding Use of enum to indicate discrete values Multilingual support Reusable code or shared libraries

Sample code 33 // This class provides the functionality // of adding numbers #include <iostream> using namespace std; class Adder{ public: // constructor Adder(int i = 0) { total = i; } // interface to outside world // Adds a number and calculates total void addNum(int number) { total += number; } // interface to outside world //get sum total result int getTotal() { return total; }; private: // hidden data from outside world int total; }; int main( ) { Adder a; a.addNum(10); a.addNum(20); a.addNum(30); cout << "Total " << a.getTotal() <<endl; return 0; }

Which one is better bool MyApplication::ReportGenerator:: GenerateReport() { bool returnValue = false; if (isAdmin() && isConditionOne() && isConditionTwo() && isConditionThree()) { returnValue = generateReport(); } return returnValue; } 34 bool MyApplication::ReportGenerator::GenerateReport( ) { if ( ! isAdmin () ) return false ; if ( ! isConditionOne () ) return false ; if ( ! isConditionTwo () ) return false ; if ( ! isConditionThree() ) return false ; return generateReport() ; }

Sample Code 35 function do_stuff() { // … if (is_writable($folder)) { if ($fp = fopen($file_path,'w')) { if ($stuff = get_some_stuff()) { if (fwrite($fp,$stuff)) { // ... } else { return false; } } else { return false; } } else { return false; } } else { return false; } } function do_stuff() { // ... if (!is_writable($folder)) { return false; } if (!$fp = fopen($file_path,'w')) { return false; } if (!$stuff = get_some_stuff()) { return false; } if (fwrite($fp,$stuff)) { // ... } else { return false; } }

36 Quality software On-time to bring customer Delight    Good Coding and Design brings >>>

Embedded system and development

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