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1. MER FIERE LEUR GU Poena E eed O 37 GREEN HILLS SOFTWARE INC WWWIGHS COM eios oes i etter e Cente ae ee acto obe dp Talde eiae Sa eig Ride eC er ce Te dolci M er eee ig diat lotta d eii ola rd QUA Ki RN 1 HANSOFT AB WWW HANSOETSE 15 5 op a ic d qi DU pani ab od nel drag do oon eb ie aci ata Soe rd Sear i i qu iab cdi 27 MENTOR GRAPHICS WW WMEN TOR COM EMBEDDED aia RR RA E AQUA QUAE RD CIARA PRET R Rd Ron geb d NRA TRE RO CV3 MICRO DIGITAL WWW SMXRIOS COM USB ESESnmn 16 MICROCHIP WY VMI ROCMIPCOWUPICKIUA deseo RE RARE ma aan Apad XE pa ERE woah 2 MOUSER ELECTRONICS WWWMOUSER COM Pre 4 6 NATIONAL INSTRUMENTS EMBEDDED ERU EE EORR E ie ed d b ded ned d OS E SE AS Gb abi asa ipid 8 NUMONYX WWWNUMONYX GCOM EMBEDDED uq ict dd ta RO UR ARR REN ERE RC PROFERRE Rea FU GRO R el x UR qutd Lp d CR AEN RE URDU ui RE 13 SMART BEAR SOFTWARE WW COD ERE VIEW BOOK COM 53 4 4 4 632 Kick el Ade uates adire acp geeignete rcg baci ebd d er Ee 37 TECH TOOLS WWW TECH TOOIS COM RUE RUPEE TEENAGERS RP p VEA REA VE RU WEEK FRU 37 TECHNOLOGIC SYSTEMS VN BNRIBEDDEBDAISNLCUDLS ick dci Eh dd d eio Do de eld eR Te Teer Reb ee did rdc ap ee re 14 TEKTRONIX WWW TEK TRONIX GOM THESOLUTION eis Ra S eap qon x dic epar e eio uen AR er once deb AR CR UR ER
2. BY NIALL MURPHY y approach to testing a graphical user interface GUI has always been to find the most appropriate access point to manually inject test cases This article will discuss the challenges of trying to make GUI tests repeatable and we ll look at a homegrown frame work that allows test input to be managed To test a GUI we need a framework that gives us the ability to inject test cas es easily and to observe the output Ide ally in a test system the output can be stored and then a subsequent test run can be compared with a previous run to provide regression testing By regression testing we mean that we have proven that the new version under test has not broken anything that used to work for the previous version If we consider a non GUI issue like message processing you might intro duce a test set of messages and then the application s message store or inbox will contain those messages If the inbox from one run is compared with the next there are two possible outcomes The in boxes may be identical this means that the new functionality has not broken previous features In some cases you might have expected changes to result from new functionality in the system under test in other words the output should have changed but didn t telling us that the new features are not working www embedded com embedded systems design GUI testing traditionally meant finding the most appropriate a
3. Run Control i S KElL ULINK A E vuwk2 Bum ma ULINK USB Adapters e JTAG SWD amp SWV support Debugging and Flash download ARM device support Data Trace for Cortex M3 ARM Instruction Trace ULINKPro 8 and 16 bit support ULINK2 Evaluation Boards RTOS and Middleware Easy implementation of complex applications Royalty free RTX Real Time Kernel TCP IP Suite with Server Applications File System for ROM and Memory Cards Direct Support for USB and CAN interfaces Flash File System USB Device Interface Examples and Templates Keil provides a wide range of evaluation boards for 8 16 and 32 bit devices CAN Interface Keil PK51 PK166 and MDK ARM support more than 1 700 microcontrollers Keil RL ARM and ART X 166 middleware suites highly optimised royalty free M The lawyers are coming hen I started writing AL UP firmware and for years f afterward few people outside of the electronics design community gave a thought to the countless embedded systems around them At the time I found it difficult to explain to most friends and relatives what exactly it was that I did for a living Yet embedded software was all around them at home and at work in their phones anti lock brakes laser printers and many other important products But to these folks software was some thing you bought in
4. October 2009 p 38 www embedded com 220100899 I wrote the book Debugging published in 2002 and still selling well because it extracts the essence of debugging which as you point out is not restrict ed to hardware and software I use examples from medicine car repair and plumbing to name a few I came up with nine rules shown on the website debuggin grules com in a free poster I chal lenge anyone to prove that I ve included a rule you can ignore or that I ve omitted a rule Your six steps and other important things are covered by my nine rules except for hypothesis fix test sequence with which I respectfully disagree My rule 3 Quit thinking and look means use your hypothesis to decide where to look next not what fix to try Trying a fix before you have seen the cause of the bug is sometimes effective but often leads to a long loop of misdirected fixes There are examples in the book The other rules are equally important in fact here they are Understand the system Make it fail Quit thinking and look Divide and conquer Change one thing at a time Keep an audit trail Check the plug Get a fresh view If you didn t fix it it ain t fixed Dave Agans Engineer DECEMBER 2009 7 NI LabVIEW Limited Only by Your Imagination Drivers for from LIDAR to GPS A hardware for drive by wire systems Image processing and acquisition libraries Multi
5. For All PIC Microcontrollers T The Microchip name and logo the Microchip logo HI TECH C MPLAB PIC and dsPIC are registered trademarks of Microchip Technology Incorporated in the USA and in other countries PICkit is a registered trademark of Microchip Technology Incorporated in the USA and in other countries All other trademarks mentioned herein are property of their respective companies 2009 Microchip Technology Inc Learn today Design tomorrow EMBEDDED SYSTEMS DESIGN VOLUME 22 NUMBER 11 DECEMBER 2009 Ama y co cdebugsg distributed systems 7 i E X BY ROLAND HOLLER AND PETER ROSSLER be 1588 used P distribute he debug process oyen the network 29 GUI testing exposing visual bugs BY NIALL MURPHY GUI testing traditionally meant finding the most appropriate access point to inject test cases The challenge however is in making the GUI tests repeatable Here s a home grown framework that allows test input to be managed replacing injectable test cases EMBEDDED SYSTEMS DESIGN ISSN 1558 2493 print ISSN 1558 2507 PDF electronic is published monthly with the exception of a combined July August issue by TechInsights 600 Harrison Street 5th floor San Francisco CA 94107 415 947 6000 Please direct advertising and editorial inquiries to this address SUBSCRIPTION RATE for the United States is 5
6. Mouser is the design engineer s one stop shop for all the board level components and associated development tools necessary for total project design The company s broad based linecard consists of components across the board from more than 390 industry leading manufacturers of semiconductors optoelectronics embedded modules as well as passives interconnects electromechanical circuit protection devices enclosures thermal management and wire cable products Www mouser com 800 346 6873 State of the Art Warehouse Operations Mouser s global corporate headquarters facility is based in Texas USA and totals 432 000 sq ft encompassing offices call and data centers as well as its state of the art warehouse The wireless warehouse management system is streamlined to nearly perfect pick and ship operations These high tech capabilities and the efficient order fulfillment processes allow for fast delivery with same day shipping on most orders received by 8 p m CST a te The 3 400 sq ft data center features a pre action fire system connections to multiple power sources and a dedicated suppression fiber communications ring to ensure uninterrupted internet operations a core component of Mouser s global sales operations Worldwide Customer Service Mouser is dedicated to providing superior service and support to customers worldwide In addition to the United States locations Mouser has sales offices around the w
7. 12 2 1 Friday October 3 proprietary MDDI This is a key differentiator because it provides a proven solution for the interconnect challenge provided by the hinge in a flip clamshell phone This reduces the wire cost and ultimately reduces the overall system cost According to the engineers at OmniVision the interface also helps reduce the EMI in the differential sig naling protocol This in turn elimi nates the need to use a parallel port where you ve got eight data bits swinging at 1 8 V with a clock and two syncs signals While the Storm obviously doesn t employ a clamshell design the EMI is reduced nonetheless Qualcomm sup ports MDDI on most of its newer chip sets Hence it gives OmniVision easier entry into a Qualcomm design DECEMBER 2009 35 tear down 36 The Blackberry Storm employs a Wideband HSPA UMTS power amplifier AWT6241 from Anadigics This part allows the phone to be used in most regions throughout the world Figure 1 While the phone was designed by RIM the designers at OmniVision were involved in integrating the sen sor into the handset This process oc curred about 18 months ago While it s obviously a hardware integration there were some software issues that OmniVision had to iron out with RIM like which settings should be used OmniVision s applica tions team worked hand in hand with RIM to get the best image quality res olution etc That
8. Most of you are familiar with the virtues of a programmer There are three of course laziness impatience and hubris Larry Wall I did say something along the lines of C makes it easy to shoot yourself in the foot C makes it harder but when you do it blows your whole leg off Byarne Stroustrup There are two ways of constructing a software design One way is to make it so simple that there are obviously no defi ciencies And the other way is to make it so complicated that there are no obvious deficiencies C A R Hoare Any fool can use a computer Many do Ted Nelson Trying to outsmart a compiler defeats much of the purpose of using one Brian W Kernighan and P J Plauger UNIX is simple It just takes a genius to understand its simplicity Dennis Ritchie Always code as if the guy who ends up maintaining your code will be a violent psychopath who knows where you live Putt s Law Technology is dominated by two types of people those who under stand what they do not manage and those who manage what they do not un derstand An organization that treats its program mers as morons will soon have pro grammers that are willing and able to act like morons only Byarne Stroustrup Theoretically software is the only com ponent that can be perfect and this should always be our starting point Jesse Poore If the code and the comments disagree both are probably wrong N
9. There are two levels of testing that are of concern when you build a GUI One is the low level graphical opera tions accessible via a function call for example drawing a line in a particular color The second type of testing is where you want to simulate events that occur on the finished product Much of this involves simulating mouse touch events on the screen or simulating ex ternal events such as changes to the analog or digital input lines We will look at each of these situations in turn TESTING LOW LEVEL GRAPHICS In many modern GUIs the low level graphics primitives are provided by a graphics library so the issue of testing this portion of the software may al ready be taken care of by the company providing the library Even if you are using a well established product you may choose to write tests for some portions of it Of course if you are creating and selling a library then you need a test in frastructure to test the whole library and being able to repeat the tests will be important at each release At www panelsoft com GUltesting htm you find an executable that runs a few simple tests of a button object The executable runs on a Windows PC and simulates the type of testing you can Guidelines confirm the button is in the correct position simulated Target LCD Display Figure 3 perform on an embedded GUI using an RS232 port as a means of getting test information out of the system Each step of
10. e Activation of breakpoints e Trace and display of register contents e Trace of internal bus activity e Synchronous replay such as previ ously recorded data from sensor interfaces e Single stepping e Start and stop of online as well as offline tests or maintenance activities e Injection of faults e Precise performance analysis 20 DECEMBER 2009 embedded systems design www embedded com These actions can be executed on a single node multiple nodes or all nodes of the distributed system in a coordinated manner IMPLEMENTATION DETAILS In the proposed solution several units are to be added to an embedded net work node typically and most effec tively on chip level to keep the task of debugging in the background and to minimize or cancel the probe effect This location is also best for the clock synchronization mechanism A node constructed according to the presented new solution thus contains a clock unit a test unit a replay unit a moni toring unit a fault injection unit a de bug unit and an offload engine which controls the aforementioned units The units are connected to the offload engine via a dedicated on chip debug bus which is separated by the system bus for the application CPUs Further more a network interface is connected to the application CPUs see Figure 2 The network interface has a built in filter that detects incoming mes sages that contain debugging com mands or clock synch
11. vokes a debugger to find out the faulty STATE OF THE ART EMBEDDED system behavior In detail the designer SYSTEMS DEBUGGING traces the execution of two nodes A To alleviate the difficulty of debugging and B simultaneously The situation is of modern microcontrollers and com similar to the plane tracking scenario plex system on chips SoCs support Obviously a systemwide notion of for test and debugging is routinely 16 DECEMBER 2009 embedded systems design www embedded com It s More Than Just Scope he all in one solution for mixed signal debug OO OOl Tektronix MSO 3034 Mixed Sigal TEN Analyze analog and digital signals with the NEW MSO3000 Series Frevu Zoom factor 40 b s Ls B 4 KE FQ I II 99 Now you can have it all with the Mixed Signal Oscilloscope Series from Tektronix With as many as 20 channels for analyzing analog and digital signals you can simultaneously monitor many points of your design And with automated decode for both parallel and serial buses you can instantly see what all those bits mean Use Wave Inspector to speed through your entire waveform in seconds or to auto matically search for an event you specify even serial packet content It s the complete all in one solution to debug today s complex designs fast And with the addition of the NEW MSO3000 Series the family just got better See for yourself
12. DECEMBER 2009 5 ouser Electronics is one of the fastest growing global catalog and web based distributors in the electronics industry Mouser is dedicated to supplying design engineers with the most rapid introduction of the newest products leading edge technologies and world class customer service Focused on design engineers and buyers demanding small to medium quantities of the latest products Mouser provides customer focused distribution Rapid New Product Introduction Mouser delivers a time to market advantage to customers with the industry s only NEW 2 100 page print catalog published every 90 days featuring the newest products and technologies Continuous updates are made to ensure the newest products are added and end of life products are removed from the catalog providing customers with easy access to the newest products and technologies E Commerce Mouser com is updated daily with new products and technologies available for customers to browse and buy online The company s website features OVER A MILLION SEARCHABLE PRODUCTS more than 900 000 downloadable data sheets 423 supplier catalogs and 1 5 million cross referenced parts The constant refinement to the site includes technical design information as well as numerous user friendly tools such as Project Manager with automatic reorder BOM import capabilities automatic order confirmation and live chat in several languages Broad Product Line
13. as one of the text fields will overlap with an icon if the text field is completely filled Changing a few of the background colors in a test build will often make these issues visible You do not want to scatter conditionally compiled background definitions throughout your code However if all of your col or definitions are arranged in one Running at full speed it s difficult to observe the changes from one tick to the next By freezing the clock the waveform can be observed as it advances from one sample to the next on each press of the return key header file changing the definition of the most common window back ground may show up most of the ob Jects of interest BUGS VERSUS TASTE One of the challenges of interpreting test failures is distinguishing between outright bugs and issues that might be open to interpretation or taste such as usability issues One tester might con sider a screen to be perfect while an other tester might consider it difficult to read because of font size or difficult to understand because of poorly worded text Other usability issues such as size or position of buttons may also be open to debate These subjective failures may be rejected by www embedded com embedded systems design developer on the grounds that the software was still meeting its explicit requirements It is important to have a process in place that allows these issues to be re solved The process might sta
14. com Managing Editor Susan Rambo srambo techinsights com Contributing Editors Michael Barr John Canosa Jack W Crenshaw Jack G Ganssle Dan Saks Larry Mittag Art Director Debee Rommel drommel techinsights com European Correspondent Colin Holland colin holland techinsights com Embedded com Site Editor Bernard Cole bccole acm org Production Director Donna Ambrosino dambrosino ubm us com Subscription Customer Service P O Box 2165 Skokie IL 60076 800 577 5356 toll free Fax 847 763 9606 embeddedsystemsdesign halldata com www customerserviceesp com Article Reprints E prints and Permissions Mike O Brien Wright s Reprints 877 652 5295 toll free 281 419 5725 ext 117 Fax 281 419 5712 www wrightsreprints com reprints index cfm magid 2210 Publisher David Blaza 415 947 6929 dblaza techinsights com Editorial Review Board Michael Barr Jack W Crenshaw Jack G Ganssle Bill Gatliff Nigel Jones Niall Murphy Dan Saks Miro Samek 0006 techinsights Corporate TechlInsights Paul Miller Chief Executive Officer Aharon Shamash Chief Financial Officer Felicia Hamerman Group Marketing Director Randall Freeborn Chief Human Resources Officer Harry Page Senior VP Professional Services Semiconductor Insights Portelligent United Business Media Corporate UBM LLC Marie Myers Senior Vice President Manufacturing Senior Vice President Strategic Development an
15. detail of the instruc tions given to the tester will vary One of the tricky things to check is the coor dinate system If this test places the but ton at position 52 26 it s desirable to measure the distance from the top or left of the display to the button Even if the pixels were large enough to be indi vidually counted checking 52 of them would be tedious and error prone One approach is to get the test code to draw a horizontal line 52 pixels from the top of the screen and then observe if the line is aligned with the edge of the ob ject under test as shown in Figure 3 Of course drawing guidelines as sumes that the lines will come out in the correct position So this test would catch a positioning bug that is specific to the button but it would not catch the case where all x positions were in correct by 3 pixels In practice you will want to do some position checks but it is too labor intensive to add guidelines for every positioned object and so once the coordinate system is tested enough to be considered trustworthy the test ing effort can move elsewhere If the test is initially run on a PC a number of options are available that might not be possible on the target One is to do a screen capture and paste the screen into a drawing tool Most drawing tools will report the position of the cursor as an x y position and so you can measure the distance in pixels between any two points in the captured screensho
16. dimensions of the selection box are shown in the bottom border which tells us that the top left corner of the button is in position 52 26 on the simulated screen z Paint Shop Pro New 7 bmp 1 1 A File Edit View Image Colors Capture Window Help Image 349 x 164 16 Milion Figure 4 www embedded com embedded systems design 9 21 gt 61 47 52 26 _ DECEMBER 2009 29 step is a function and a table of point ers to functions dictates the order in which they will be called Commenting out some portions of the table allows a bunch of tests to be temporarily dis abled Part of the array might look like Listing 1 Each function name in the list rep resents a step of the test Note that the ButtonClick part requires two entries in the table This is because the har ness progresses to the next step each time the tester presses return and some tests require more than one press of the return key to check all parts In this case there is a setup step and a check at end step Most of the time it is a purely semantic issue whether such setup and check pairs are consid ered to be two parts of one test or whether they are considered to be two tests that have a dependency on each other EVENT CHECKING In the case of the button test the reason two steps are required is that at the first step the tester is prompted to click on or touch the button and then on the second step the test code confi
17. embedded systems design www embedded com THE BIG PICTURE Most of the discussion so far has as sumed that individual graphical ob jects are being tested In many cases the underlying objects are trustworthy but the application logic needs to be tested I generally use the same test harness to test the application but in stead of calling individual functions of the object s interface I fake mouse touch events or eternal events that have an impact on the appearance of the interface such as an alarm Oth er external stimulation might be a varying analog signal that is being graphed on the GUI Simulating the external data some times means replacing a function such as readAnalog function with code that accesses a table of test data in stead of the analog hardware Creating false button presses is sometimes more challenging than you would think If there are 10 buttons on the display the test code may not have pointers to those objects The only pointer to them might be inside the window or group object that contains them and since that window contains many other objects it might not be trivial to query the window for the specific button that you require In some cases the creation order of the objects is known For example the test author might know that the fifth object created within a window is the button the required for the test So the test code iterates through the list of buttons contained by the window un
18. means that a problem with the button tests will not impact the slider tests Within the suite of tests for button sectioning the numbers as 1 1 1 2 1 3 and so forth Previous tests often set up the right state the best place for a new test might be after some closely related test that has the right conditions and then another section as 2 1 2 2 etc will allow a new test to be added without having to reorder every fol lowing test In theory you could have used the rule that new tests must al ways be added at the end but in prac tice previous tests often set up the right state in which you can best run the new test so the best place for a new test might be just after some closely related test that has set the right conditions There will often be a bit of code that must be run before or after each test sometimes a function to refresh the display or to flush all pending events is required Also during devel opment you want a lot of control over which tests are run and in what order For example if I am having trouble with test 4 16 I may want to run that test several times making alterations each time but I do not want to run every preceding test each time To achieve this I want to temporarily disable all the tests before 4 16 In some cases I will want to keep any tests that set up the conditions re quired for test 4 16 These requirements lend them selves to a structure where each test The
19. performed a very similar calculation Listing 2 contains another example this time in C with the bug finding left as an exercise for the reader You can find the full set of slides from my talk online at http bit ly badcode TOTAL RECALL Lest you think that the evidence from the presentation are DECEMBER 2009 11 Listing 1 single line of unintelligible mystery code x 305 146097 1461 exceptions to the norm found because I and other engineers were on the prowl for bad code consider just a couple of ex amples stemming from the more obvious embedded software failures First recall the Patriot Missile failure in Dhahran Saudi Arabia during the first Gulf War Twenty eight U S soldiers were killed when a Scud missile was not shot down due to im proper tracking by the Patriot Missile battery protecting a mil itary base A report from the U S Government Accountability Office examined the events leading to the failure and conclud ed the problem was partly in the requirements the govern ment didn t tell the designer it would need to operate contin uously for long periods of time Huh At the time of the incident the battery had been operating continuously for over 100 hours Now consider a more recent example GPS maker Garmin announced a free mandatory GPS software update to correct a software issue that has been discovered to cause select GPS devices to repeatedly attempt to update GP
20. were raised should be cleared At this point the heap size should be exactly the same as it was at the start If not you should suspect a leak When the test code arrives back at the starting state there should be no partially processed events Any win dows that were opened should be closed Any alarms that were raised should be cleared At this point the heap size should be exactly the same as it was at the start If not you should suspect a leak Be aware that in some designs ob jects will consume space the first time they are used For example the first time an alarm occurs space might be allocated for the alarm message All following occurrences then use that same piece of storage So one sequence through the test will result in a heap that is bigger at the end than it was at the start For this reason I prefer to run this sequence twice I ignore any heap growth on the first run of the test but the second run should not cause any further growth If there is growth in the heap this test may detect it but it does not iden tify the exact cause There is further discussion of how to pinpoint the cause of a memory leak in my More on Memory Leaks article 32 DECEMBER 2009 embedded systems design www embedded com LOGGING AND PACING Many types of applications lend them selves to test by log file where a test is stimulated and as the application per forms actions they are also logged to a file or tran
21. 5 for 12 issues Canadian Mexican orders must be accompanied by payment in U S funds with additional postage of 6 per year All other foreign subscriptions must be prepaid in U S funds with additional postage of 15 per year for surface mail and 40 per year for airmail POSTMASTER Send all changes to EMBEDDED SYSTEMS DESIGN P O Box 3404 Northbrook IL 60065 9468 For customer service telephone toll free 877 676 9745 Please allow four to six weeks for change of address to take effect Periodicals postage paid at San Francisco CA and additional mailing offices EMBEDDED SYSTEMS DESIGN is a registered trade mark owned by the parent company TechInsights All material published in EMBEDDED SYSTEMS DESIGN is copyright 2009 by TechInsights All rights reserved Reproduction of material appearing in EMBEDDED SYSTEMS DESIGN is forbidden without permission COLUMNS barr code 11 The lawyers are coming BY MICHAEL BARR The quality of a lot of embedded software is abysmal And lawyers are on to it If you don t want your source code to show up in court you better get your act together break points 38 Programming quotations BY JACK G GANSSLE Jack Ganssle presents some of the best programming related quips for your enjoyment and instruction DEPARTMENTS include 5 CPU vendor buys OS vendor Part Il BY RICHARD NASS Caviums acquisition of MontaVista is very similar to a deal that went down not too long ago parity hit 7 t
22. DN a E RR d 18 neck on your re Web Servers Technology Web Enable Imost Anything nr Almost Nothing the Suef ef Const Technion www embedded com embedded systems design DECEMBER 2009 37 Programming quotations O death where is thy sting O grave where is thy victory ose words ring with Shakespeari an power Hamlet King Lear Ac tually the quote comes from the New Testament I image the Bible is the most quot ed book of all time My parents would paraphrase a parable or cite a verse to make a point or correct our behavior The nuns at St Camillus did too and a sure way to curry favor with them was to quote chapter and verse Even the most secular couples often use 1 Corinthians 13 in their weddings The world abounds in aphorisms that convey wisdom to the young al though that advice is usually ignored Many aphorisms are by unknown au thors A stitch in time saves nine al though anyone who has repaired a sail knows that one stitch can actually save 9 000 People who live in glass houses shouldn t throw stones And many wit ty people have contributed their own like this gem from Mae West Lead me not into temptation I can find the way myself Pithy quotes and aphorisms can en tertain and instruct Often they do both Engineers can turn a clever phrase as well as Mae West I ve collected quips that relate sometimes unintentionally to deve
23. Einstein Some people when confronted with a problem think I know I ll use regu lar expressions Now they have two problems Jamie Zawinski Debugging is like alien abduction Large blocks of time disappear for which you have no explanation The most amazing achievement of the computer software industry is its contin uing cancellation of the steady and stag gering gains made by the computer hardware industry Henry Petroski One test is worth a thousand opinions Unknown If the lessons of history teach us any thing it is that nobody learns the lessons that history teaches us Unknown The trouble with the world is that the stupid are cocksure and the intelligent are full of doubt Bertrand Russell Debugging is like alien abduction Large blocks of time disappear for which you have no explanation Unknown Most software today is very much like an Egyptian pyramid with millions of bricks piled on top of each other with no structural integrity but just done by brute force and thousands of slaves Alan Kay If builders built buildings the way pro grammers wrote programs then the first woodpecker that came along would de stroy civilization Gerald Weinberg Ugly programs are like ugly suspension bridges they re much more liable to col lapse than pretty ones because the way humans especially engineer humans perceive beauty is intimately related to our ability to process and
24. I s frame buffer so a certain amount of integration between your system and the test tool is required The amount of effort required to get the tool up and running will depend on your operating system and hardware platform At the other extreme all tests could be manual where the test document in structs the tester to press certain but tons in a certain order and then ob serve the results While this approach does not require any code to be written it is extremely weak for a number of reasons One is that it is very time con suming for the tester to read instruc tions before each button press If the tester makes a mistake he will most likely have to restart a sequence At the end of a sequence if the output is not correct the tester will be left wondering if the test failed because of a bug or be cause they might have pressed the wrong button without realizing it so they may run the sequence again just to be sure An even bigger disadvantage is that you can not call specific functions using the method above In some cases you may want the tester to press on a but ton then simulate some external event that causes an alarm to appear on the display and then get the tester to release the on screen button These are the sort The second step of the test suite shows the font size being changed of scenarios that often expose bugs But scenarios that have exact sequence or timing requirements may be impossible L Bitton
25. If you lie to the compiler it will get its revenge Henry Spencer There are only two industries that refer to their customers as users Edward Tufte Einstein argued that there must be sim plified explanations of nature because 38 DECEMBER 2009 embedded systems design www embedded com Jack G Ganssle is a lecturer and consultant on embedded development issues He conducts seminars on embedded systems and helps companies with their embedded challenges Contact him at jack amp ganssle com God is not capricious or arbitrary No such faith comforts the software engineer Fred Brooks Jr To iterate is human to recurse divine L Peter Deutsch Good judgment comes from experi ence and experience comes from bad judgment Fred Brooks There are two ways to write error free programs only the third works Alan J Perlis When Leo Tolstoy wrote Anna Karenina he could have been thinking about cubi cles there are no conditions of life to which a man cannot get accustomed es pecially if he sees them accepted by everyone around him Leo Tolstoy The real value of tests is not that they detect bugs in the code but that they de tect inadequacies in the methods con centration and skills of those who de sign and produce the code C A R Hoare The most important single aspect of software development is to be clear about what you are trying to build Byarne Stroustrup
26. K20 MICROCHIP bojeuy HI TECH C Compilers PRO for PIC10 12 16 18 32 running in Lite Mode nee FT Los ee ee Aa Ra n et tit A 44 pin demo board with a E Abhe c LJ microcontroller One Low Price 69 99 Microchip s PICkit 3 Debug Express part number DV164131 incorporates in circuit debugging technology to provide an extremely affordable hardware debugger and programmer for the entire range of Microchip s Flash Microcontrollers MCUs from the smallest 8 bit MCU through all 16 bit dsPIC DSCs to the largest 32 bit PIC32 MCU PICKit 3 runs under the popular MPLAB IDE the free graphical integrated development environment software complete with programmer s editor software simulator and project manager MPLAB IDE S GUI promotes advanced debugging with a host of auxiliary features such as a segmented LCD Designer a graphics display designer and a data monitor and control interface Easily connected to the PC with a USB interface PICkit 3 is bundled with a demo board for fast learning and initial design prototyping The two wire interface easily connects to the final designs for application tuning and quick in circuit programming m m U 2 lt 72 With rich features free compilers fully integrated with MPLAB IDE and a suite of tutorials Microchip PICkit 3 Debug Express delivers substantial value at a remarkably low price
27. S firmware and then either shut down or no longer acquire GPS satellite sig nals This sounds to me like a bug in their bootstrap loader a k a bootloader Many Garmin GPS units are named as af fected including members of the popular n vi product family Or consider what a consumer had to say about his Cele stron SkyScout Personal Planetarium recently in a forum at Amazon com I m downloading the second firmware update release since I ve had my SkyScout about 3 weeks Each re lease is making the device more stable Listing 2 Find the bug in this code snippet bool Probe getParam uint32 t param id int32 t idx i int32 t val 0 10132 t ret 0 ret m pParam readParam param id idx amp val if Clret i logMsg attempt to read parameter failed n exit 1 else 12 DECEMBER 2009 embedded systems design www embedded com 400 x 305 146097 36524 4 x 305 146097 36524 1461 365 100 x 305 146097 36524 Finally consider these quotes from the recent recall of a device regulated by the U S Food and Drug Administra tion an AED automatic external defibrillator e Units serviced in 2007 and upgraded with software ver sion 02 06 00 have a remote possibility of shut down during use in cold environmental conditions There are no known injuries or deaths associated with this issue The units will be updated with the current version of softwa
28. Test Demo Simulated Target LCD Display for a human to reproduce Similarly if the test requires that an on screen event happens at an exact x y location the tester cannot guarantee that that acted on the exact required lo cation especially on a touchscreen with no visible mouse Finally testing the system with no access to the code means that the test nn internal r can not access internal data structures Simulated Hyperterm window on target s RS232 port at the end of the test to check if they peterem Snc have the correct values The tester might be able to observe on screen or E RUE ambe external state but they have no visibili Step 1 2 Complete ty of the state changes internal to the software that occurred during the test ROLL YOUR OWN A simple test framework can exercise test cases in your GUI These test cases Figure 2 ke Lake s 2 a i a 1 um gt 409 34 gt Space Systems Swedish Space Corporation E 3 TU T C cw BORNE COLLAS CHEDULING lt Download a free 2 user solution trial at www hansoft se www embedded com embedded systems design DECEMBER 2009 27 can not be fully automated because a human observer must confirm the ap pearance of the GUI They allow the tester to run them in a reasonably effi cient fashion and they make it straight forward to ensure that one test run is consistent with the previous run
29. View the virtual product demo Mixed Signal Oscilloscope Series Features 4000 Series New 3000 Series 2000 Series Bandwidth 1 GHz 500 MHz 350 MHz 500 MHz 300 MHz 100 MHz 200 MHz 100 MHz Analog Channels 4 20r4 20r4 Digital Channels 16 MSO Series 16 MSO Series 16 MSO Series Record Length 10 M points 5 M points 1 M points Display 10 4 9 7 Serial and Parallel Bus Analysis IC SPI CAN LIN FlexRay RS 232 Audio Parallel 2C SPI CAN LIN RS 232 Audio Parallel 12C SPI CAN LIN RS 232 Parallel Optional Analysis Packages Power Analysis HDTV and Custom Video Power Analysis HDTV and Custom Video see the family in action View the virtual product demo www tektronix com thesolution Tektronix 2009 Tektronix Inc All rights reserved Tektronix products are covered by U S and foreign patents issued and pending TEKTRONIX and the Tektronix logo are registered trademarks and Wave Inspector is a trademark of Tektronix Inc built into silicon Today many debug ging approaches rely on offline debug ging based on trace buffers added to the CPU to reduce intrusiveness by the debug system Leading processor core vendors offer on chip trace solutions However existing debugging and test tools are mainly focused toward single nodes with one or more CPUs on board or on chip SoC by using auxiliary debug in terfaces like JTAG or a simple UART The problem of these ap proaches is that they entirely neg le
30. a box at a store and installed on the one computer you owned Today of course there are countless embedded systems per person and our health and wellbeing are both greatly en riched by and increasingly de pendent upon proper func tioning of the firmware inside Consumers now notice them and think of them as software containers if only because they require frequent reboots and upgrades And there is no let up in sight several billion more such devices are produced each Lawsuits are on the rise too In recent years I ve been called into U S District Court as an expert witness in sev eral dozen lawsuits involving embedded software I ve met others with similar experiences and become aware of many other cases Popular claims range from copyright theft and patent and trade secret infringement to traditional prod Michael Barr is the author of three books and over 50 articles about embedded systems design as well as a former editor in chief of this magazine Michael is also a popular speaker at the Embedded Systems Conference and the founder of embedded systems consultancy Netrino You may reach him at mbarr netrino com or read more by him at www embeddedgurus net barr code The quality of a lot of embedded software is abysmal And lawyers are on to it If you don t want your source code to show up in court you better get your act together www embedded com embedded systems design ucts liabili
31. ary LM3S e Maxim 3421 NXP ISP LPC Sharp LH7 ST Micro STR7 9 STM32 Features USB 2 0 compliant e Low full amp high speed e All transfer modes Small amp fast e Easily portable Standalone operation e Royalty free cap licensing e Full Source Code serial Cy ze TP 48 T Micro Digital E USB SOFTWARE LEADER 800 366 2491 sales smxrtos com www smxrtos com usb DECEMBER 2009 23 EE TIMES ACE AWARDS 2010 Tuesday April 27 2010 Presented at the Embedded Systems Conference silicon Valley CALL FOR ENTRIES 2010 EETIMES ACE AWARDS EE Times presents The 6th Annual EETimes ACE Awards The Annual Creativity in Electronics ACE Awards celebrates the creators of technology who demonstrate leadership and innovation in the global electronics industry and shape the world we live in If you or your company has made significant achievements in 2009 enter today to see if you can become part of a prestigious group of finalists and winners recognized by EE Times editors a distinguished judging panel and the global electronics industry m CATEGORIES DESIGN TEAM OF THE YEAR MOST PROMISING NEW TECHNOLOGY INNOVATOR OF THE YEAR EDUCATOR OF THE YEAR EXECUTIVE OF THE YEAR STUDENT OF THE YEAR STARTUP OF THE YEAR MOST PROMISING RENEWABLE ENERGY AWARD COMPANY OF THE YEAR Entry Deadline January 22 2010 No cost to enter allows test input to be managed replacing manual test cases GUI testing
32. ca tions industrial and building automation as well as machine and plant control to name a few As already mentioned a global notion of time is a key el ement for distributed debug ging Therefore the proposed so lution for distributed debugging implements a mechanism to synchro nize the local clocks contained in the network nodes The clock synchro nization mechanism can be imple mented either in software or in hard ware The latter option however provides a better accuracy If for ex ample the IEEE 1588 clock synchro nization standard is applied to a 100 Mbit s Ethernet network the clock synchronization mechanism can be implemented in hardware right above the physical layer which allows Comparison between a traditional approach to debug distributed systems a and the proposed new solution b Shared or switched network S 3 mee Monitoring computer 1 Monitoring computer 2 Issues debug and test commands to Node 1 Issues debug and test commands to Node 2 Figure 1 T NES Monitoring computer n Issues debug and test commands to Node n www embedded com embedded systems design K Shared or switched network switched network Monitoring computer Issues debug and test commands to all nodes without using an auxiliary interface DECEMBER 2009 19 cover feature synchronization of the local clocks with a precision of abo
33. ccess point to inject test cases The challenge however is in making the GUI tests repeatable Here s a homegrown framework that exposing visual bugs DECEMBER 2009 25 The second possibility is that the outputs are different If the inbox mes sages can be expressed in text format some text difference tool can show those inconsistencies and the engineer can examine them to decide if the changes match the new functionality For example if an urgency field has been added to the messages a message identifier might change from Message index 17 message title test 185 title to Message index 17 message title test 185 title urgency normal If the only changes in the output are consistent with this we have suc cessfully added the urgency feature and we have not broken anything else It would be great to apply the same principle to graphics but the challenge is that the appearance of the display can not usually be expressed in a humanly readable text format This means that it is tricky to examine differences The output of a GUI test is the appearance of the screen which is a large number of pixels and each pixel has a color val ue While a human being can view the screen and establish if the text 1s read able and the layout conforms to re quirements the job of checking if each pixel has the correct numerical value or color is a nontrivial task A screen capture tool could record the screen and a compa
34. ce allocated to them on the screen When the product has been translated into a foreign lan guage the same test can be run to en sure that the translated strings do not overflow the areas that were sufficient in the English version If all translated strings can be gen erated in a simple list I usually print out that list and tick off each string as it is viewed in the test so that at the end I can tell at a glance if there is a translated string that did not get tested MEMORY MANAGEMENT Some GUI libraries use the heap and some do not major concern is whether use of the GUI library leads to any memory leaks Letting a GUI run for days and checking memory con sumption occasionally does not really stress the heap If there is a memory leak it is caused by the response to a particular event So the key to testing the heap is to measure heap size and drive a sequence of events and then at the end of that sequence check if the heap has grown So the memory management test should start at some neutral state where there are no outstanding events on the GUI Then the test code should navigate through every screen trigger every conceivable event and then nav igate back to its starting position The external events may be things like alarms that cause a warning to popup on the display or anything else that leads to GUI interaction C windows that were opened should be closed alarms that
35. ckberry as some 000 qualities and some The imaging and telephony functions were up to snuff The UI left a little to be desired BY RICHARD NASS Storm d d not so goo he BlackBerry Storm came out not too long after I purchased my Blackberry Curve Like lots of the latest consumer electronics de vices youre always hesitant to jump in and make a purchase because you know your device will be trumped by something cooler in a very short time That was the case with my Curve but not exactly Shortly after I ac quired my Curve the Storm crossed my desk as the object of a Tear Down My first inclination with a Tear Down is to try the device out for a while to get a feel for the user experience In this case it was to see what I was missing out on To my surprise and delight I found out that the Storm doesn t have a better user experience In fact I like my Curve better The biggest rea son for that is the touch interface that accompanies the Storm I found it quite difficult to press the right buttons I may have big fingers but they re not so big that I should have that much trouble with the interface Being the engineer that I am I decided not to let that one design flaw completely ruin the user experience although it was hard to get 34 DECEMBER 2009 embedded systems design ww embedded com th AT ED m T passed that point I found that as a telephone the Stor
36. core algorithms for real time navigation and control Standard communication including JAUS and Ethernet support RF LabVIEW graphical programming PRODUCT PLATFORM software and modular NI hardware such NI LabVIEW graphical Medical as CompactRIO and PXI are helping and textual programming engineers develop fully autonomous NI CompactRIO embedded i trol hard Robotics robotics systems including unmanned contro hardware NI LabVIEW Real Time Module NI LabVIEW FPGA Module vehicles designed to compete in DARPA Multicore Grand Challenge events NATIONAL P INSTRUMENTS Jack Ganssle responds Also do check out Steve Litt s site troubleshooters com In Jack s column Developing a good bedside manner he writes In other cases just as in medicine one bug may present a variety of odd effects Or a single symptom could stem from a combination of bugs all interacting in excruciating complex and hard to diagnose manners I wonder if physi cians observe the infrequent symp toms we see that appear in a system once go away for weeks and then randomly resurface I liked being the Hero that caught the elusive bug as much as anyone But do we really have to let the bugs go away for weeks How much time and money are spent chasing these bugs How much does it cost when we fail to catch them Are we not smart people with sys tems of our own design and under our own control These bugs can be eas
37. crucial part since the hardware support alone does not make much sense without any user in terface to operate and control debug ging and testing of the distributed sys tem Currently the operator software is based on the well known tools GDB GNU Project Debugger and Eclipse to offer full state of the art source lev el debugging support for all nodes of a distributed system according to the so lution we present in this article APPLICATION SCENARIOS With respect to both CPU clock speed and data throughput real time video imaging applications where several high speed high resolution cameras operating in an ensemble intercon nected via 10 Gbit s Ethernet are among the most challenging systems to debug A precisely coordinated ap proach to debug and test such systems is as innovative as promising In telecom applications network interconnect is increasingly moving from circuit switched or time division to internet protocol based solutions often relying on Ethernet network tech nology At the same time requirements for precisely retaining systemwide 2 048 M Hz or 4 096 MHz sampling rates have to be fulfilled IEEE 1588 clock synchronization is therefore cur rently built into such systems in many places Including IEEE 1588 would at the same time enable corresponding coordination of test and debugging support if taken into account Distributed systems are also ram pant in industrial automation Here real time is
38. ct the distributed nature of many ap plications since to connect a monitoring computer directly to each node is impractical especially if the nodes are already embedded in their place of installation see Figure 1a Wouldn t it be nice to precisely co ordinate debug test trace and replay activities across the entire distributed system without the use of any auxiliary interface or special cabling Moreover it would be helpful if only a single de bugging master and monitoring com puter is attached to the network used to issue debugging test or monitoring actions Such an approach that greatly Wouldn t it be nice to precisely coordinate debug test trace and replay activities across the entire distributed system without the use of any auxiliary interface or special cabling simplifies debugging and testing of distributed systems is shown in Figure 1b A NEW SOLUTION FOR DISTRIBUTED DEBUGGING In the following example a distributed system is assumed that contains a plu rality of nodes where every node is a self contained processing unit with pe ripherals or in other words an em bedded system The nodes are con nected via a network for example cover feature Ethernet and exchange data to jointly perform their application tasks No re strictions shall apply to the underlying network technology be it wire less or cable bound shared or switched Today such setups are deployed in automotive appli
39. d Business Administration Pat Nohilly CPU vendor buys 05 vendor Part II know I m a little late to the party on this one but I need to put my two cents in here When In tel made the acquisition of Wind Riv er I was all over it so it s only fair that I make a comment on what looks to be a similar situation Cavi um s acquisition of MontaVista It s a similar situation because it s a microprocessor vendor swallowing up an operating system vendor The only difference is that it s on a smaller scale a significantly smaller scale Intel reportedly paid somewhere in the neighborhood of 800 million for Wind while Cavium paid only 50 million The former was the largest processor company purchasing the largest embedded software vendor That s not the case with Cavium MontaVista but the similarities are still there This acquisition could be good for existing MontaVista customers as it gives them a great growth path to a very high end microprocessor How ever it s doesn t bode well for the mi croprocessor vendors except for Cavium of course MontaVista claims that it will continue to sup port all the microprocessor vendors that it currently works with and it s a pretty long list Hmm That sounds familiar The Wind folks made that same claim The jury is still out on Wind but they re sticking to their story of sup Richard Nass is the director of content media at TechInsights You may reach h
40. dent ed insights in the execution flow of dis tributed systems M Roland Heller and Peter R ssler are re sponsible for R amp D projects at the Univer sity of Applied Sciences Technikum Wien Austria They ve worked many years in the area of ESL design FPGA and digital ASIC design PCB design as well as clock synchronization and con trol networks The work described herein receives support by the City of Vienna Department MA27 grant numbers MA27 Project 04 11 and MA27 Project 05 05 and the Austrian Research Agency FFG grant number 818647 Look like to a PC USB disk drive USB serial device USB keyboard amp mouse Audio with MIDI Ethernet over USB RNDIS Composite devices USB disk drives USB serial devices USB keybds mice HIDs USB audio devices USB modems USB printers USB to Ethernet adapters USB to serial adapters USB to WiFi w WEP amp WPA Multi port y www embedded com embedded systems design Connect with the leader In embedded USB software Micro Digital provides integrated USB solutions that run out of the box with our SMX RTOS file system and TCP IP stack These robust high performance USB solu tions are written in ANSI C and can run on any hardware platform with SMX another RTOS or stand alone Connect with us today at www smxrtos com usb USB Controllers Supported OHCI UHCI EHCI OTG Atmel AT91 e Cirrus EP ColdFire e Freescale i MX Lumin
41. e a bus network like CAN seems ap propriate instead of Peer to peer RS232 or maybe bus RS 485 422 the very advantage CAN has in the form of message based communi cations becomes a burden while designing your app around it Es pecially as the author also points out when it comes to combining the various incarnations of CAN Ba sic Full enhanced Dirk Buijsman Lead Software Engineer The article was good but a small erra tum SPI mentioned as System Packet Interface is a network protocol I guess the author intends to print Serial Pe ripheral Interface Raj Miriyala Firmware Engineer Thank you very much for this nice ar ticle I would like to bring up a little point that J1939 implementers will ap preciate According to SAE spec J1939 has to run at 250 kbit sec This makes When it comes to setting up CAN for the first time while the protocol is robust flexible and with the Full Enhanced controllers takes hardly any effort for your MCU the initial design can be very tricky J1939 bit timing to 4 microseconds Since 1 bit is 8 to 25 time quanta make sure your oscillator can run at a perfect frequency so that your CAN device can meet the SAE spec Umut Tezduyar Software Engineer Doctors and debugging I was quite interested in Jack Ganssle s use of the medical diagnosis analogy Jack Ganssle Developing a good bed www embedded com embedded systems design side manner
42. e test harness that makes it possible 28 DECEMBER 2009 embedded systems design www embedded com to manage lists of these tests Once the harness is in place it provides a home for tests to be added for new features or in response to bugs How the harness is coded will de pend on the communications mecha nism available but a serial port is typi cal At each step some test code is run and the tester is prompted to check the display for certain properties The ex ample test code tests a button object and Figure 1 shows the state at the end of the first step which simply tests the construction of a button object A step like this requires the tester to confirm that the button is visible and its text is readable The test code will often check internal values For exam ple a call to the button s getText O function could be checked to see if it returned the string Press me The ad vantage of these checks is that they do not require any human interaction and so do not add to the test time Pressing Return on the RS232 in terface probably using a terminal emu lator program on a PC will advance to the next step Figure 2 shows this dis play after the tester has advanced to the next step This step modified the font used in the object that has already been created Changing the appearance in each small step allows the tester to ob serve if an operation that changes the object has the desired effect The level of
43. ear down 34 marketplace 37 advertising index 37 IN PERSON ESC Grenoble December 1 3 2009 www design reuse com 1pescO9 ESC Silicon Valley April 26 29 2010 www embedded com esc sv ESC Chicago June 8 9 2010 http esc chicago techinsightsevents com ESC India July 21 23 2010 www esc india com ESC Boston September 20 23 2010 www embedded com esc boston ESC UK October 12 14 2010 www embedded co uk ONLINE www embedded com The Newest Embedded Technologies New Products from RABBIT amet MiniCore RCM5600W Wi Fi No MEE USD T WAN DO OF Module Lm ETO OTH RFID gt WLA N j AdaptivEnergy 9 la C mit Joule Thief Energy Harvesting al a 00 mic Joule Thief Module J Laudi gt Ly F PE SO CEL P California Eastern Laboratories 21 2410 MeshConnect Module The ONLY New Catalog Every 90 Days Experience Mouser s time to market advantage with no minimums and same day shipping of the newest products from more than 390 leading suppliers es mmi MICROCHIP a tti company The Newest Products For Your Newest Designs MRF24J40MB 2 4 GHz RF Transceiver Module WWW mouser com Over A Million Products Online 800 346 6873 EMBEDDED SYSTEMS DESIGN Director of Content Media TechInsights Richard Nass 201 288 1904 rnass techinsights
44. eful to replay cer tain data streams from peripheral units The task of the replay unit is to record data from external units such as GPIOs general purpose input out puts UARTs universal asynchronous receiver transmitters and DACs dig ital to analog converters and to allow playback at later times The monitoring unit is connected to the system bus as a passive listener and tracer It records all or a filtered subset of accesses to the main system bus to allow a detailed history of trans A precisely coordinated approach to debug and test such systems real time video imaging appli cations is as innovative as promising actions to be transferred to the debug ging master for off line debugging Fault injection is a method to assess system capabilities like fault detection fault isolation or recovery In software testing fault injection is used to test Overview of a distributed system based on the proposed solution for distributed debugging and details of the hardware support built into the embedded nodes 1 05 memories sensors actuators Node CPUs Test structures Monitoring Test structures Monitoring Network interface with offload engine Clock Clock synchronization Network interface Test Replay Monitoring 1 05 memories sensors actuators Node CPUs synchronization Fault Injection Debugging Operator Computer Figure 2 1 05 memories sensors actuat
45. erase 512 k 128 Mb single I O M325PX AKB block erase 4 Mb 64 Mb 3M multi L O M25PE M45PE page erase TMb 16 Mb av NUMC ELL PARALLE NOR LAS A AOR Product Family 4 Mb 2 Gb M29W EW command set P30 33 Intel based command set sync burst 64 Mb 2 Gb numonyx innovative memory solutions TS 8100 Ultra Reliable w 128MB ECC RAM Qty 1 Oty 100 269 229 shown w optional SD Card 400 MHz PowerPC w Floating Point Unit POE ready Dual execution unit Double precision FPU Multifunctional PC 104 connector 12K LUT customizable FPGA 512MB NAND Flash 1 USB Host 1 USB Device 12 Mb s Boots Linux 2 6 in 2 seconds Fanless 4W sleep mode 1mW Regulated 5 28V power input 5 10 bit ADC 2 SDHC sockets 4 COM ports 2 10 100 ethernet SPI amp DIO RS485 RS422 TS 8150 available w extra data acquisition features a Over 20 years in business Never discontinued a product Engineers on Tech Supp Open Source Vision Custom configurat excellent pricing an SYSTEMS ed aan Technologic We use our stuff visit our TS 7800 powered website at www embeddedARM com 480 837 5200 amp WatchDog 2 DMX Channels entering the courtroom in criminal cases involving data collection devices with software inside Consider the precedent setting case of the Alcotest 7110 After a two year legal fight sev en defendants in New Jerse
46. five or ten years Joseph Licklider Code generation like drinking alcohol is good in moderation Alex Lowe Do you have favorites Post them on embedded com LOWER YOUR BOM NOT YOUR EXPECTATIONS MEET THE OS DEPLOYED IN 1 4 BILLION DEVICES Reliably With Express Logic s award winning BenchX IDE or use tools from over 20 commercial offerings including those from ARM Freescale Green Hills Microchip MIPS Renesas and Wind River Ll With Express Logic s small fast royalty free and industry leading RTOS NetX TCP IP stack FileX FAT file system and USBX USB stack Easily With Express Logic s graphical TraceX event analysis tool and new StackX stack usage analysis tool See exactly what is happening in your system which is essential for both debugging and optimization e Confidently No matter what it is you re developing Express Logic s solutions will l help you build it analyze it run it and ship it better and in less time Join the success of over 600 000 000 deployed products using Express Logic s ThreadX BENCH THREAD TRACE STAC K logic For a free evaluation copy visit www rtos com 1 888 THREADX d contu system M
47. gn Guide Go to to learn about Our site also allows you to access Cree s Product Characterization Tool to Compare up to three LED models simultaneously Calculate lumens per dollar and other valuations Identity the best Cree LEDs for your design designing high power LEDs into luminaires Visit www arrownac com cree to get started now lt p ww b oy 1 888 9LIGHT1 www arrownac com cree cover feature IEEE 1588 can be used to distribute the debug process over the network Coordinated debugging of distributed system BY ROLAND HOLLER AND PETER ROSSLER magine a world without a global notion of time Now try to find out the flight direction of an airplane with the following information There s an e mail from Alice that she saw the plane about two hours after sunrise and another e mail from Bob that he saw the plane about three hours after sunrise So Alice and Bob tell us when they saw the plane at least from their point of view If they are nice they might give us some additional information namely their location at the moment of the observation But unfortunately embedded sys tems are usually not that nice Now imagine a distributed system time would be helpful which leads us built of networked embedded nodes to an important aspect in distributed When a problem arises with the dis debugging tributed application the designer in
48. h Hofstadter s Law It always takes longer than you expect even when you take into account Hofstadter s Law DECEMBER 2009 39 PHP is a minor evil perpetrated and created by incompetent amateurs whereas Perl is a great and insidious evil perpetrated by skilled but pervert ed professionals Jon Ribbens If you want a girlfriend avoid working in the computer games industry like the plague If you work seven days a week 15 hours a day for almost two years with barely enough time for a pint you have no time whatsoever for relation ships Plus computer games makers are regarded as being about as hip and cool as abattoir workers Toby Gard Your problem is another s solution your solution will be his problem Unknown Embedded lines of code are growing 2696 annually but developers are in creasing by 896 Venture Development Corporation Productivity can decrease by as much as 25 when workers put in 60 hour weeks for a prolonged time And turnover is nearly three times higher among workers who work extended hours Absenteeism among companies with extended hours is more than twice the national average Reworded from Circadian Technologies Shiftware Practices 2005 survey There s a fine line between being on the leading edge and being in the lunatic fringe Frank Armstrong Two things are infinite the universe and human stupidity and I m not sure about the universe Albert
49. he target embedded system see Figure 2 All these local actions are controlled by an offload engine without having the node s application CPUs to run a single line of additional debugging or test related code Although the proposed solution is aimed for an implementation on hardware level it s also possible to implement it in software This would allow a less expensive implementation This enables complex test or debug scenarios where the sequence of events can be independent of net work packet delays even if the nodes are distributed as no special chip has to be designed but comes with some restrictions and drawbacks The major drawback is the intrusiveness of the software ap proach since the debugging software task can significantly change the sys tem behavior BENEFITS OF THE SOLUTION An unprecedented coordination of the plurality of nodes in the distributed system is reached by deriving the trig gers for trace debugging or any other activities from the synchronized clocks as well as to enable cross triggering between the hardware support units of the nodes This enables complex test or debug scenarios where the sequence of events can be made independent of network packet delays even if the nodes are distributed in space An informal collection of some possible scenarios that would greatly disburden the task of testing and de bugging in a distributed system could mention e Start and stop of code execution
50. ih Learn today Design tomorrow United Business Media 00200060 VOLUME 22 000000 NUMBER 11 0000060 DECEMBER 2009 NEM dsl 2 Embedded Design The Official Publication of The Embe bedded Sys ystems ns C Conferences and Embedded com 3 a i i 1 A Besse wA Nd A E psa i ij aane pe m NM k e Barr See you in court Debugging a GUI Ganssle Programming quips Intel Core 17 Processor Based Mobile Platform i E T PCIE a x A 6U VPX 3U VPX 6U cPCI 3U cPCI VME E E Intel Core i7 Processors Unmatched Performance Extreme Engineering Solutions Inc X ES unleashes the performance of the Intel Core i7 processor for use in commercial military and aerospace applications The mobile Intel Core i7 processor delivers unmatched power savings and processing performance Extreme Engineering Solutions offers an extensive product portfolio that includes commercial and ruggedized single board computers high _ performance processor modules multipurpose 1 0 modules backplanes Extreme Engineering Solutions enclosures and fully integrated systems 608 833 1155 WWW X es com Call or visit our website today INTEGRITY RTOS has it No one else does ATS National Information Assurance Partnership Common Criteria Certificate Note This evaluation comtains
51. ile for Separation Kernels in Environments Requiring High Robustness Version 1 03 29 June 2007 Original Signed By Director Common Criteria Evaluation and Validation Scheme Information Assurance Director National Information Assurance Partnership National Security Agency The NSA has certified INTEGRITY technology to EAL6 and High Robustness INTEGRITY is the most secure real time operating system available and the first and only technology to have achieved this level High Robustness is a higher level of security than EAL6 It includes 133 additional security mandates over and above the 161 required for EAL6t When security is required Green Hills Software s INTEGRITY RTOS technology is only option ay ill M Green Hills SOFTWARE INC www ghs com Copyright 2009 Green Hills Software Inc Green Hills the Green Hills logo and INTEGRITY are trademarks of Green Hills Software Inc in the U S and or internationally All other trdemarks are the property of their respective owners One Debugger Programmer S49 043u020J2IIN A CD that includes PICkit 3 User s Guide series of 12 lessons on PIC MCUs with C source code A debugging tutorial 19 01 U0 gt 5 jeubis jeubig PICkit 3 Microchip s MPLAB IDE software u debugger Free MPLAB C Compiler for all LI sicco PIC MCUs and dsPIC DSCs AN CCS compiler for the PIC18F45
52. ily captured if we make proper use of our software to help us The vast majority of embed ded systems can be instrument in software by the developer to record and then replay the software execu tion The data rate of a proper imple mentation is surprising low 2KB per MHz of CPU clock A rate that is lower than typical instrumentation approaches that pump out informa tion that we think will help us find these bugs The record process saves the min imum data that is needed to capture the exact execution process of the software Therefore the real time exe cution is not being changed by the analysis and debug processes The replay process recreates the recorded execution with the bugs Complete analysis and debugging takes place in the replay process with out changing the recreated execution of the software So what s the big disadvantage It requires a change in the typical embedded mindset Robert Coker Former Embedded Systems Engineer ARM wrestling Rich Nass says it s likely that there will be no clear cut winner Richard Nass 15 billion sockets up for grabs November 2009 p 5 www embedded com 220900316 It s clear to me ARM WINS Leandro Gentili Software Engineer In terms of safety gazing at the code is analogous to organizing the deckchairs on the Titanic as you steam toward the Requirements Iceberg at least it keeps you occupied ARM less performance I do no
53. im at rnass techinsights com porting all the necessary micro processors Similarly we ll have to wait and see if MontaVista holds true to their word Cavium and MontaVista were close partners before the acquisition and both claim they ll work with the other s competitors So I ask the same question I asked a few months ago why make this acquisition And I come to same conclusion over time MontaVista will end the support for Cavium s competitors It s a natural progression as those competitors be gin toz lose trust in MontaVista Think about it If you re proces sor vendor X why would you let MontaVista in on your secrets which is required to continue support when there s the possibility a strong possibility that those secrets will find their way back to Cavium your competition MontaVista will claim that that won t happen but I m not sure if I d be willing to take that bet if I m vendor X and there are alterna tives to MontaVista So who s next It s too late to buy Embedded Alley as they were ac quired by Mentor Graphics earlier in the year a very smart move in my opinion That one was a little differ ent as it was an OS vendor buying another OS vendor But there are still plenty of operating system compa nies available And there are lots of processor companies who may feel the need to join the club Richard Nass rnass techinsights com www embedded com embedded systems design
54. ion equipment 5 GAO s report can be found at www fas org spp starwars gao im92026 htm 6 In fact soldiers in Israel had previously discovered that the Patriot Missile soft wares ability to track an incoming missile degraded in just eight hours and they had a software upgrade to fix it 7 http garmin blogs com my weblog 2009 06 ask garmin free mandatory gps software available now html 8 www time com time world arti cle 0 8599 1902421 00 html 9 www dwi com new jersey state v chun 10 Full expert findings reports www dwi com new jersey base one find ings defendants and www dwi com new jersey new jersey code review state Atrow Y Hor Everything You Need to Design in Cree LEDs Arrow and Cree have built an intuitive information packed website to help you design the optimal Cree LEDs into your solid state lighting applications Get the facts you need to know and then select the right Cree LEDs Tor your lighting class architectural and general illumination designs With Arrow s world class support you can rest assured you re choosing the best products and benefiting trom unrivaled services solutions and technical know how Visit our site and learn all about New Cree LEDs oolutions that will get you to market fast Relevant white papers and other technical papers raining opportunities Related design tools Download the Cree Lighting Desi
55. led to OmniVision doing some scripting for the Storm and tuning the image parameters like the lens correction and the defect correc tion so the image looks the best regard less of temperature The OmniVision developers also had to ensure that they provided the modes for all image sizes THE MAKINGS OF A WORLD PHONE The power amplifier PA in the Storm 17073 0506 E J i OCCO ES T POH OSS ETET ITTY LE Designers shouldn t get too hung up on saving components at the expense of good matching between the components and the RF subsystem is a Wideband CDMA HSPA UMTS model the AWT6241 from Anadigics The device provides the amplification for the phone s 3G mode This particu lar model is a world phone that runs on Verizon s CDMA network in the U S It enters roaming mode while in Europe taking advantage of a GSM EDGE power amplifier RIM chose the AWT6241 because of its high efficiency and high output power The device is part of Anadigics DECEMBER 2009 embedded sustems design www embedded com third generation High Efficiency Low Power HELP3 product line It s real claim to fame is its low quiescent cur rent and the high efficiency at backed off power The result is a longer battery life which is essential in a device like that Storm that contains a touch screen a web browser an e mail client and lots of other bells and whistles For the IMT band the 6241 i
56. light computer instead made decisions only on the basis of the one failed unit More than 100 of the 300 people on board were hurt with broken bones neck and spinal injuries and severe lacerations splattering blood throughout the A lawsuit is pending TAKE A DEEP BREATH Firmware bugs seem to be everywhere these days So much so that firmware source code analysis is even When it comes to creating your next embedded system an important decision awaits you Memory Your design needs speed reliability performance and capacity to store the code and data your design demands No problem Numonyx has the broadest portfolio of parallel and serial NOR NAND and phase change memory And we offer extended temperature support with AEC Q100 certification on many of our products and expanded design versatility with voltage support up to 5V All designed to deliver a right fit solution to help you shorten design cycles reduce development costs and accelerate the roll out of your next big idea Find out how Numonyx memory matters for your next design Visit www Numonyx com Embedded for free access to the Numonyx Embedded Design Center 2009 Numonyx B V All rights reserved Includes stacked solutions T Avallable on specific densities rOther names and brands may be claimed as the property af others NUMONYX FORTE SERIAL FLASH MEMORY Product Family Density Range Voltage Solution M325P block
57. lopment for many years Here s some of the best Testing by itself does not improve soft ware quality Test results are an indica tor of quality but in and of themselves they don t improve it Trying to im prove software quality by increasing the amount of testing is like trying to lose weight by weighing yourself more of ten What you eat before you step onto the scale determines how much you will weigh and the software development techniques you use determine how many errors testing will find If you want to lose weight don t buy a new scale change your diet If you want to improve your software don t test more develop better Steve McConnell Programming can be fun so can cryp tography however they should not be combined Charles Kreitzberg and Ben Shneiderman The sooner you start to code the longer the program will take Roy Carls Our developers never release code Rather it tends to escape pillaging the countryside all around The Enlightenment Project Documentation is a love letter that you write to your future self Damian Conway Perl is the crystal meth of program ming it s so incredibly useful when you need to do a large amount of work in a small amount of time that you tend to overlook the fact that it s basically pre cipitating the implosion of your vital organs Dan Martinez Programmers are the tools for convert ing caffeine into code Unknown
58. m worked really well And that s an important compo nent although I use the phone more for e mail and texting than I do as a phone nobody calls anybody any more do they The second feature I found to be quite attractive was the imaging quali ty both for still images and for video So that s where my Tear Down start ed I wanted to find out what was the cause of those qualities that I found to be so appealing The sensor that s in the Blackber ry Storm is from OmniVision Tech nologies the OV3647 It s a low pow er low cost CMOS image sensor Containing a parallel interface as well as a mobile digital display interface MDDI the sensor has a resolution of 3 Mpixels running at 15 frames s It has embedded phase locked loop PLL and can be embedded into a module that s 7 by 7 by 5 mm as is the case in the Storm It has an em bedded 1 5 V regulator for operation at full power but the core power is about 1 4 V The OV3647 which is related to the sensor in RIM s Blackberry Curve handset the OV2640 supports a raw RGB output format image sizes of QV XGA and XGA and has a pro grammable frame rate Image quality controls like lens correction auto ex posure auto gain auto balance and defect pixel canceling help enhance the images along with support for LED and flash strobe mode One of the unique features of the OV3647 is that it contains Qual www embedded com embedded systems design tear down
59. n Another common flaw that is ex posed by this technique is where one component is drawn but then com pletely covered by some overlapping objects Since there was no benefit in drawing the elements that get covered the software could be optimized to re move that step A second method for slowing down the GUI is to disable the clock that drives the on screen events Each time the tester presses return the clock is advanced a few ticks I have found this very useful when testing wave forms that are tracking some analog input such as an oscilloscope display Running at full speed it is difficult to observe the changes from one tick to the next By freezing the clock the waveform can be observed as it ad vances from one sample to the next on each press of the return key BORDER CROSSINGS The alignment of objects and whether they overlap is often only visible if the borders of the object are visible In many cases those borders are deliber ately invisible For example a piece of text will often not show its bounding box A bitmap can use the back ground color so that it floats on the background instead of appearing as a rectangle For test purposes seeing those boundaries is important if we want to ensure objects do not overlap Fields that vary in length such as names and addresses entered by the user might look OK when the data is short but cause problems if the field is filled completely Figure 6 illustrates this
60. nt produced over 19 000 warnings about the code that s about three errors for every five lines of source code 14 DECEMBER 2009 embedded systems design ww embedded com What would you infer about the re liability of a defendant s blood alcohol reading if you were on that jury If youre so inclined you can read the full expert reports for yourself A BETTER WAY Don t let your firmware source code end up in court Adopt a coding stan dard that will prevent bugs and start following it don t wait a day Run lint and other static analysis and code complexity tools yourself rather than waiting for an expert witness to do it for you Make peer code reviews a reg ular part of every working day on your team And establish a testing environ ment and regimen that allows for re gression testing at the unit and system level These best practices won t ensure perfect quality but they will show you tried your best I ll have more to say about keeping bugs out of embedded software in my next few columns Meanwhile try not to think about all the firmware upon which your life depends M ENDNOTES 1 www vdcresearch com documents press release press attachment 1503 pdf 2 Minor details including variable names and function names were changed as needed to hide the specifics of applica tions companies or programmers http bit player org 2009 the zune bug Hint This code was embedded in a piece of factory automat
61. often defined with respect to time constants of mechanical sys tems such as motors which typically are in the range of several 1 us As Giga bit network bandwidth is also begin ning to break into this area CPU clock speeds and application complexity are very likely to be increased accordingly Automotive systems have just started to step to higher bandwidth for exam ple FlexRay communication technology with 10 Mbit s data rate The predicted shift from federated toward integrated architectures will very likely further in crease complexity in those systems as multiprocessor break by wire chips are already being designed both due to relia bility and performance reasons A sys tematic approach to debugging and test precisely coordinated amongst the col laborating embedded control units promises to greatly ease efforts during system bring up as well as maintenance UNPRECEDENTED INSIGHT Testing and debugging of a distributed system is known as a complex task The presented solution enables the develop er to gain control over all the nodes in a distributed system in a coordinated re producible and if required a nonin trusive manner The main difference to existing approaches is the fact that the proposed one takes the distributed character of the system into account The combination of precisely synchro nized clocks with hardware support for test replay fault injection monitoring and debugging allows for unprece
62. ombia In terms of safety gazing at the code is analogous to organ izing the deckchairs on the Ti tanic as you steam toward the Re quirements Iceberg at least it keeps you occupied The most pertinent statement in the article is Finally expertise is de manded Competence and profes sionalism should not be implicit or assumed when the systems are high dependability Interestingly standard IEC 61508 provides guidance on competence assessment For interested readers there is a DO 178B group on LinkedIn Martin Allen Software Safety Specialist We welcome your feedback Letters to the editor may be edited Send your comments to Richard Nass at rnass techinsights com or fill out one of our feedback forms online under the article you wish to discuss DECEMBER 2009 9 s Development Solutions C and Development Tools Best in class Keil and ARM compilers for small fast code e Genuine Keil pVision IDE Debugger Simulator Fast development and verification using Device Simulation Easy device configuration with Device Database support for more than 1700 devices Microcontroller Development Kits C and C Compilers Royalty Free RTX RTOS py Vision Device Database amp IDE pu Vision Debugger amp Analysis Tools Examples and Templates Complete Device Simulation RTOS and Middleware Components RTX RTOS Source Code TCPnet Networking Suite Debug
63. orld including Singapore Shanghai and Hong Kong as well as Germany UK and Israel Mouser believes in providing the best customer service regardless of the size of the customer or the size of the order Breaking packs and no minimum orders including one piece shipping is especially attractive to engineers working in the earliest stages of the engineering design cycle USER ELECTRONICS a tti company The Newest Products For Your Newest Designs Mouser and Mouser Electronics are registered trademarks of Mouser Electronics Inc Other products logos and company names mentioned herein may be trademarks of their respective owners CAN it be possible hile it is nice to see an article on CAN I m not sure whether it really lives up to its title Hassane El Khoury CAN in 30 minutes or less November 2009 p 20 www embedded com 220900314 Some CAN history bit timing and tool screenshots but not a single example of where such tools are found or how to setup CAN from scratch with them Nonetheless the author is ab solutely right when it comes to set ting up CAN for the first time while the protocol is robust flexi ble and with the Full Enhanced controllers takes hardly any effort for your MCU the initial design can be very tricky There are some free implementations available Pelican VSCP CAN Open De viceNet but when you want to do something simple where these protocols simply don t fit wher
64. orm Schryer Always code as if the guy who ends up maintaining your code will be a violent psychopath who knows where you live pamian Conway www embedded com embedded systems design Documentation is a love letter that you write to your future self Damian Conway If you think good architecture is ex pensive try bad architecture Brian Foote and Joseph Yoder Theory is when you know something but it doesn t work Practice is when something works but you don t know why Programmers combine theory and practice nothing works and they don t know why Unknown If the code and the comments dis agree then both are probably wrong Unknown Those who want really reliable soft ware will discover that they must find means of avoiding the majority of bugs to start with and as a result the programming process will become cheaper If you want more effective programmers you will discover that they should not waste their time de bugging they should not introduce the bugs to start with Edsger Dijkstra In theory there is no difference be tween theory and practice In practice there is Yogi Berra For a successful technology honesty must take precedence over public rela tions for nature cannot be fooled Richard Feynman One of the main causes of the fall of the Roman Empire was that lacking zero they had no way to indicate successful termination of their C programs Robert Firt
65. ors Node CPUs Test structures Monitoring Network interface with offload engine Network interface with offload engine Clock synchronization Shared or switched network 22 DECEMBER 2009 embedded systems design www embedded com rarely reached parts of code If required such functions can be supported and as a consequence coordinated across the entire distributed embedded system The debug unit is designed to con nect to the debugging interfaces of the application CPUs The unit s functions are for instance to halt the processors of one chip to single step through in structions to add and remove break points and to allow access to processor internal registers The use of a highly synchronized time base from the clock unit allows the debugging operator computer to perform a coordinated halt or single step of the complete dis tributed system or a remote reset after a nonrecoverable crash of the node The application CPUs contained in the nodes are the processing units that perform the actual application task The single or multiple processors are connected to peripheral units like sen sors and actuators as well as to the communication controller Due to the nonintrusiveness of the debugging functionality the application CPUs are unaware of any extra load caused by commands sent from or received by the debugging operator computer The software running on the oper ator computer is a
66. re e All of the recalled units will be upgraded with software that corrects another unexpected shutdown problem In the meantime it is vital to follow the step 1 2 3 op erating procedure which directs attachment of the pads after the device has been turned on This procedure is de scribed on the back of your device and also in the Quick Reference material inside the AED 10 case Some pages in the user s manual may erroneously describe or show il lustrations of a different operating procedure Please disregard these erroneous instructions At least one death was reported at a time when the second type of unexpected software shutdown occurred Are bugs in the embedded software to blame for that too If not how did the User s Manual come to be out of sync with the firmware in a process driven FDA regulated envi ronment Given the above is it not appropriate to wonder if the unexplained loss of Air France 447 over the Atlantic Ocean earlier this year was firmware related An abrupt 650 ft dive an Airbus A330 flight experienced in Oc tober 2006 may offer clues to the loss of Air France 447 Authorities have blamed a pair of simultaneous computer failures for that event in the fly by wire A330 First one of three redundant air data inertial reference units began giving bad data Then a voting algorithm intended to handle precisely such a failure in one unit by relying only on the other two failed to work as designed the f
67. results 15 awarded to that are not mutually recognized in llr prada rase d Green Hills Software Inc CCRA only the ev luntiom resulis of EALA components are mutually recognined The IT product identified in this certificate has been evaluated at an accredited testing laboratory using the Common Methodology for IT Security Evaluation Version 2 3 for conformance to the Common Criteria for IT Security Evaluation Version 2 3 ISO IEC 15408 This certificate applies only to the specific version and release of the product in its evaluated configuration The product s functional and assurance security specifications are contained in its security target The evaluation has been conducted in accordance with the provisions of the NIAP Common Criteria Evaluation and Validation Scheme and the conclusions of the testing laboratory in the evaluation technical report are consistent with the evidence adduced This certificate is not an endorsement of the IT product by any agency of the U S Government and no warranty of the IT product is either expressed or implied Product Name INTEGRITY 178B Separation Kernel CCTL Science Applications International Corporation Evaluation Platform INTEGRITY 178B Real Time Operating Validation Report Number CCEVS VR VID10119 2008 System RTOS version IN ICR750 0101 GHO01 Rel running on Date Issued 01 September 2008 Compact PCI card version CPN 944 2021 021 w PowerPC Protection Profile US Government Protection Prof
68. rison tool could simply point out if the screen shot has changed and then allow the These are the sort of sce narios that often expose bugs but exact sequence or timing requirements may be impossible for a human to reproduce tester to view the old and new image In theory this is a good approach but it can be very labor intensive The rea son is that the number of screenshots The first step of the test creates a button Simulated Target LCD Display Test started Step 11 Button Object constructor Text is Press Me Check button text is visible Step 1 1 Complete Figure 1 Simulated Hyperterm window on target s RS232 port 26 DECEMBER 2009 embedded systems design www embedded com for a GUI can be very high Usually it is desirable to capture the screen after every user event such as button press or external event some alarm condition occurred Unfortunately one global change can cause a change to all of those screenshots For exam ple changing the default font or back ground color or making the margin at the left of the screen a little wider will cause a change in every screenshot that has been gathered Commercial tools are available to help automate the process just de scribed and while I would not discour age their use be aware that in this con text automated testing does not mean labor free testing The other restriction of these tools is that they need access to the GU
69. rms if the tester did in fact click on the button For this to work the first step has to set up the button s event handlers in such a way that the click is recorded in some boolean flag In the second step the flag is checked If it is still false the event never registered Either the tester did not follow the instructions or the event handling has a bug If you run the demo executable and if you do not click on the button when instructed the next step will print a failure message Because the event handler also prints a message to the serial port the tester could have just observed that there was a response to the event However checking a flag Creating false button presses is sometimes more challenging that you would think If there are 10 buttons on the display the test code may not have pointers to those objects means that there is less reliance on the tester and therefore less opportunity for human error A similar approach should be tak en to any other objects that the tester manipulates If the tester is instructed to move a slider to its maximum the tester can be instructed to check the on screen value of the slider and the test code can also query the internal stored value Both checks are necessary to ensure the object is storing and dis playing its value correctly Zooming in on a shows that antialiasing is not being used and b shows that it is a Figure 5 b 30 DECEMBER 2009
70. ronization information and directs those mes sages to the offload engine Other mes sages are forwarded to the application CPUs which are unaware of the filter ing mechanism Regarding transmis sion the network interface has the abil ity to insert packets containing information related to debug and test from the offload engine into the trans mit buffers during idle times of the network The offload engine comprises the subsystem that is responsible for pro cessing messages for clock synchroniza tion and debugging Its task is to read incoming debugging and clock syn chronization packets and to transfer the information to the corresponding unit clock test replay monitoring fault in jection or debug unit The perform ance of the offload engine can be signif icantly lower than the performance of the application CPUS since the task of cover feature forwarding messages to the units on the debug bus is relatively simple and the clock synchronization calculations are only repeated at a low frequency The test unit s task is to perform self test operations in the node and to offer a network enabled test access port to the system for example by im plementing JTAG ports to connect to off chip components That way a de vice contained on a node could be configured through the TAP master in the test unit which is for example helpful for maintenance purposes To reproduce complex debugging setups it might be us
71. s compatible with the Qualcomm chip set which is really the heart and soul of the Storm says Bruce Webber director of marketing for Anadigics wireless products Sometime next year we ll have our fourth generation HELP parts which offer even further improvements in efficiency and quiescent current Note that in the design of a hand set there are some shortcuts you can take and others you should avoid Handsets are obviously space con strained and designers would prefer to use a single sided board rather than a double sided board Webber says One of the things we ve seen is that the continuing drive to reduce board area and BOM costs is causing people to leave out matching components They ll try to do a one or two component match and sometimes that s not ideal You need to leave your self enough flexibility to match the power amp to the duplexer that s select ed for best power output efficiency Otherwise you can end up having prob lems with linearity or even oscillation under some circumstances Anadigics provides reference de signs for many of its parts And the company is quick to point out that de signers shouldn t get too hung up on saving components at the expense of good matching between the compo nents and the RF subsystem Because that s where you can achieve the high efficiency good linearity and low spu rious emissions while simultaneously resulting in good RF performance The end
72. smitted on a serial port Generating the log file depends on the application including a logging fea ture which might be conditionally compiled Following the test examina tion of the log file will indicate if the correct actions took place This is par ticularly useful if the actions are diffi cult to observe externally On a GUI by definition almost everything is vis ible externally and log files are not used very much There are a few cases where I have found logging revealed things that would have been difficult to spot on the display A log file that records each item drawn on the display makes it possible to see the order in which they were drawn and also if an item was drawn twice It is not unusual to have a bug in a GUI that leads to part of the display being updated twice Such a bug is relatively harmless but it is a waste of CPU cycles to draw the same items more than once Since the final state of the GUI is the same a tester might not spot this However if a log file is examined and it states that cer tain items were drawn more than once then the problem can be identified Another way to detect the same style of problem is to deliberately slow down the GUI Add a delay in some low level drawing routine and the whole GUI will move in slow motion You will see the display being gradual ly built up as different elements are drawn If an item 1s drawn then erased and then drawn again you will see this happe
73. t Figure 4 shows an example using Paint Shop Pro Once you have done a screen cap ture you also have the chance to zoom in to examine the details This is espe cially useful if the screen is of high res olution and subtle details like anti aliasing at the edge of letters can not be easily seen with the naked and some times aging eye Figure 5 shows how zooming in allows us an up close view of the anti aliasing being applied Part a shows no anti aliasing When this is rectified part b shows the edges being anti aliased The color choices for the softening of the edges are not ideal and this is due a limited color palette If this is rectified in software the changes to the edges of the letters would be quite subtle and zooming would be vital to examine the change A typical PC simulation copies the target screen pixel for pixel On some projects I have modified the simula tion to allow an option of doubling the number of pixels in the horizontal and vertical directions This effectively is a 20096 zoomed view of the target and can be very useful when examining the details CODE ORGANIZATION A good test harness must make it easy to insert and remove tests Each set of tests should be runnable independent of the last set to allow them to be run in reasonable size chunks For exam ple all of the button tests might be built as one executable and so they can be run completely independent of the slider tests This
74. t think so The ARM architecture appears to be dominating the small device space by a pretty decent mar gin too Ken Wada Sr Embedded Systems Consultant DO 178B To set the record straight on DO 178B Aviation incidents caused by software systems are thankfully rare even given the exponential growth of software density in aircraft systems perhaps this is a consequence of pre scriptive standards guidelines such as DO 178B and their enforcement by certification authorities e g FAA Designated Engineering Representa www embedded com embedded systems design tives A major criticism here Jack Ganssle Software for dependable sys tems November 2009 p 37 www em bedded com 220900315 of the book Software for Dependable Systems is it is not prescriptive enough DO 178B is far from perfect but it has known strengths such as its bias toward requirements and their satisfaction The guideline contains more than 60 objectives Many people concentrate on a select number of code based objectives e g MC DC coverage but this is a gross misinter pretation and misrepresentation of DO 178B DO 178B is limited in scope and it fails to address the holistic system aspects of safety Still this article falls into a similar trap with too much emphasis latterly on coding languages such as Ada and SPARK Note systems containing perfectly functioning code have con tributed to fatal accidents such as Cali Col
75. te that no usability issues are to be addressed at the test phase or it might state that the project leader will arbitrate if the tester and developer cannot agree if a partic ular test has failed or you could hand all power to the tester and allow him to fail any test where he thinks the look of the GUI might not meet cus tomer expectations As long as the process is understood by all sides it can avoid endless debate between de velopers and testers FIRST IMPRESSIONS LASTING IMPRESSIONS Testing the visual elements of your GUI is vital because the GUI forms the customer s first impression of the product and any quality issues in the GUI will be interpreted as quality is sues for the whole product Different areas of software will always require some tweaking of the test methods employed to maximize the number of bugs caught and hopefully some of the techniques shown here will help you track down a few extra GUI bugs Niall Murphy has been designing user interfaces for over 14 years He is the author of Front Panel Designing Soft ware for Embedded User Interfaces Murphy teaches and consults on build ing better user interfaces He welcomes feedback and can be reached at nmur phy panelsoft com His web site is www panelsoft com ENDNOTES 1 Murphy Niall More on Memory Leaks Embedded Systems Programming April 2002 available on line at www embedded com story OEG2002032180021 DECEMBER 2009 33 Bla
76. the test performs some small change on the GUI and either the test code or the tester checks that the ap propriate change has happened For almost all graphics projects there are huge advantages to making the system work on a desktop computer as well as on the target All commercial For almost all graphics projects there are huge advantages to making the system work on a desktop computer as well as on the target embedded GUI libraries support this arrangement This applies to the final product code but it also applies to the test code The tests can be developed far more quickly on the PC with a simulat ed display The completed tests are then run on the target system which will uncover any problems that arise on the target that were not an issue on the PC The PC simulation and the target dis play should be pixel for pixel identical in theory but you can still get bugs that occur on the target but not on the PC Problems with running out of memory or timing issues are possible sources of trouble Also the PC is likely to be driv en by a mouse while the target may use a touchscreen This difference might disguise some problems on the PC STEP BY STEP The demo test does a few very simple checks on the functionality of the but ton object in the system under develop ment but for the purposes of this ex ample we are not concerned with whether the button is being fully tested We are more concerned with exploring th
77. til Listing 1 typedef void TestFn void TestFn TestList TestCreateButton TestFontSize TestButtonClick1 TestButtonClick2 it reaches the fifth one This approach is not entirely satisfactory since minor changes to the order of construction will break the test Some libraries will allow you to seek a button without knowing the pointer For example the PEG library allow an identifier which is an integer to be associated with any object A findC function is available in the top level window which will recursively search all windows to locate the object with the a matching identifier This is better than the previous approach but still has weaknesses One is that the identifiers are not necessarily unique so two buttons in two different windows might have the same identifier The sec ond problem is that it only locates ob jects that are on the display The test code may need to access an object be fore it becomes visible in order to alter some of its properties Another approach that doesn t re quire pointers to the button objects is to generate mouse touch events at a low level and the x y position of those events is set to correspond to the posi tion of the required button This has the drawback that changing the posi tion of a button means that the test might not work as expected While I would not recommend this method for all testing there are some cases where generating low level mouse
78. touch events are ideal If you want to test what happens when you touch the edge of the button specify ing the x y position allows you to sim ulate a user s touch on an exact loca tion that sits on the button s border Note that this is something that would be impossible for a human tester to do on a touchscreen since the human fin ger is just not that accurate Another example of a test that suits this method is where you simulate a press down event inside the button and a re lease event outside the button If you plan for it early in the devel opment cycle the buttons and other objects required for testing can be reg istered with the test harness using some enumeration type to index them in a table which will make them al ways accessible to the test code This registration step is often conditionally compiled code within the application itself Adding code to the application in order to allow the test harness to work is not ideal since it can make the This has the drawback that changing the position of a button means that the test might not work as expected build process more complex but in this case it may be justified if it means that we get a clean mechanism for fak ing button events At this point you might be thinking that faking button presses might be more trouble than it is worth If the tester has to press return at the end of each step why not let the tester press the button on the GUI and a
79. ty with a firmware twist Unfortunately the quality and relia bility of our collective firmware leaves the door open to an ever in creasing number of the latter THIS CODE STINKS At a recent Embedded Systems Conference I gave a popular free talk titled This Code Stinks The Worst Embedded Code Ever in which I used lousy code from real products as a teaching tool The ex ample code was gathered by a num ber of engineers from a broad swath of companies over several years Listing 1 shows just one exam ple of the bad code in that presenta tion I don t know if the snippet contains any bugs as most of the other examples were found to And that s a problem Where are we sup posed to begin an analysis of the code in Listing 1 What is this code supposed to do when it works What range of input values is ap propriate to test What are the cor rect output values for a given input Is this code responsible for handling out of range inputs gracefully The original listing had no comments on or around this line to help I eventually learned that this code computes the year with accounting for extra days in leap years given the num ber of days since a known reference date such as January 1 1970 But I note that we still don t know if it works in all cases despite it being present in an FDA regulated medical device I note too that the Microsoft Zune Bug was buried in a much better formatted snippet of code that
80. understand complexity A language that makes it 40 DECEMBER 2009 embedded systems design www embedded com hard to write elegant code makes it hard to write good code S Raymond Let us change our traditional attitude to the construction of programs Instead of imagining that our main task is to in struct a computer what to do let us con centrate rather on explaining to human beings what we want a computer to do Donald Knuth The most unsuccessful three years in the education of cost estimators appears to be fifth grade arithmetic Norman Augustine No engineer looks at a television remote control without wondering what it would take to turn it into a stun gun No engineer can take a shower without wondering if some sort of Teflon coating would make showering unnecessary To the engineer the world is a toy box full of suboptimized and feature poor toys Scott Adams I love deadlines I like the whooshing sound they make as they fly by Douglas Adams In handling resources strive to avoid dis aster rather than to attain an optimum Butler Lampson There are various reasons that software tends to be unwieldy but a primary one is what I like to call brittleness Soft ware breaks before it bends so it de mands perfection in a universe that prefers statistics Jaron Lanier People tend to overestimate what can be done in one year and to underestimate what can be done in
81. user might not be aware of all the stuff that goes on inside but they certainly know when a call gets dropped adds Webber MI EMBEDDED SYSTEMS MARKETPLACE PG 850 eis An nalyzers T NE 9499 00 he Compact LIMES 5 4 1 SIB is a small low cost yet powerful Server that is ideal for hostile rugged environments amp has the following features eFanlessx861GHzCPU e256MBDDR2RAMOnBoard e128MBlInternalFlashDisk 2 6KERNEL e10 100Base T Ethernet i eOnBoard Audio EEE e2RS 232 amp 3USB2 0Ports Pricing eCompactFlash amp MicroSDSlots Starts eReliable NoCPUFanorDiskDrive at AL eOptionalWirelessLAN amp HardDrive 230 00 EON eDimensions 4 5 x4 5 x1 375 http www emacinc com linux compact sib htm Bear Sj Sa Since 1985 JI I cli inc I SOFTWARE EQUIPMENT MONITOR AND CONTROL SOLUTIONS Phone 618 529 4525 e Fax 457 0110 e Web www emacinc com Advertiser URL Page ARM KEIL KEIRCOM 43 auskao t gc CRGA en EE E ado pA ERES RE VR QUERER PER RA a ERR RA Rl 10 ARROW WWW ARROWAC citet ee oe o b acepten coda dr ace e ca dde dpi dara dread iac ol ar 15 EXPRESS LOGIC WWWRIOS COM PT FUTURE ELECTRONICS WWW FUTUREELECTRONICS COM VIDEO TOUR gt COEUR Rob ERE RH VC o e aoo dae ous Ica ERR RR Rel NN 21 GEIST TECHNOLOGY GEIS TER COM
82. ut 10 ns This enables systemwide debugging of multiple nodes at the CPU instruc tion level assuming CPU clock rates up to 100 MHz If the network pro vides an implicit clock synchroniza tion mechanism such as time trig gered protocols like TTP or FlexRay this clock can be used for debugging purposes Besides the clock synchronization mechanism the second key element in the proposed approach for distributed debugging is the usage of the already existing network to transfer debugging data During normal operation the network does not exhibit any addi tional traffic Even the clock synchro nization although typically not show ing higher traffic than one short message per second in case of IEEE 1588 can be turned off if not needed The nodes jointly perform their appli cation tasks its normal operation without the need of interaction To en able debugging and testing a debug ging master or monitoring computer running a debugging program has to be connected to the network First clock synchronization will be activated to enable the common notion of time During a debugging session the de bugging master transfers messages containing debugging commands to one or multiple nodes Each node re sponds to the received messages and performs the intended tasks In an integrated approach dedi cated hardware units are added to each node that facilitate test replay moni toring fault injection or debug ac tions in t
83. void the need to generate button events from the test code In practice it would be very difficult to get the tester to follow an exact sequence of button presses In many cases the test may require multi ple buttons for one step the interme diate states in the GUI may already have been tested so the goal is to check the final state that resulted from many user events SHOWING ALL STRINGS A test suite that displays all test strings is very useful especially if the GUI is going to be translated into foreign lan guages Each step of the test navigates to a different state or changes some Part a looks fine but changing the background colors in b reveals that the address field is too wide and overlaps with the neighboring Icon Name Jane a Address 12 Main Street FAITE Name Jane b Address 12 Main Street 7 Figure 6 www embedded com embedded systems design DECEMBER 2009 external condition to display a string that has not been seen before Of course there are many strings that get seen at multiple steps of the test The OK string in one of your buttons might be visible at almost every test step The serial port output of each step should identify which of the strings on the display have not already been viewed on a previous step Once you have a test that displays all strings you can be confident that you will catch any strings that are too long to fit in the spa
84. y drunk driving cases successfully won the right to have their experts review the source code for the Alcotest firmware The state and the defendants both ultimately produced expert reports evaluating the quality of the firmware source code Although each side s ex perts reached divergent opinions as to the overall code quality several facts seem to have emerged as a result of the analysis e Of the available 12 bits of analog to digital converter precision just 4 bits most significant are used in the actual calculation This sorts each raw blood alcohol read ing into one of 16 buckets I won der how they biased the rounding on that e Out of range A D readings are forced to the high or low limit This must happen with at least 32 consecutive readings before any flags are raised e There is no feedback mechanism for the software to ensure that ac tuated devices such as an air pump and infrared sensor are ac tually on or off when they are sup posed to be e The software first averages the ini tial two readings It then averages the third reading with that aver age Then the fourth reading is av eraged in and so on No com ments or documentation explains the use of this formula which causes the final reading to have a weight of 0 5 in the average and the one before that to have a weight of 0 25 and so forth e Out of range averages are forced to the high or low limit too e Static analysis with li

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