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  • GORM "getNextException" equivalent

    - by Josh K
    GORM sits on top of [Hibernate](http://en.wikipedia.org/wiki/Hibernate_(Java). The issue is that sometimes Hibernate will throw exceptions from the JDBC driver that I can't figure out how to investigate. Specifically: Could not execute JDBC batch update; /* snip */ Caused by: java.sql.BatchUpdateException: /* snip */ [insert] was aborted. Call getNextException to see the cause. If it makes any difference I'm using PostgreSQL.

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  • Quering computed fields in GORM

    - by Tihom
    I am trying to query the following HQL using GORM: MailMessage.executeQuery("toId, count(toId) from (SELECT toId, threadId FROM MailMessage as m WHERE receiveStatus = '$u' GROUP BY threadId, toId) as x group by x.toId") The problem is that count(toId) is a computed field doesn't exist in MailMessage and that I am using a subquery. I get the following error: java.lang.IllegalArgumentException: node to traverse cannot be null! Ideally, I would like to use a generic executeQuery which will return data of anytype. Is there such a thing?

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  • Mission critical embedded language

    - by Moe
    Maybe the question sounds a bit strange, so i'll explain a the background a little bit. Currently i'm working on a project at y university, which will be a complete on-board software for an satellite. The system is programmed in c++ on top of a real-time operating system. However, some subsystems like the attitude control system and the fault detection and a space simulation are currently only implemented in Matlab/Simulink, to prototype the algorithms efficiently. After their verification, they will be translated into c++. The complete on-board software grew very complex, and only a handful people know the whole system. Furthermore, many of the students haven't program in c++ yet and the manual memory management of c++ makes it even more difficult to write mission critical software. Of course the main system has to be implemented in c++, but i asked myself if it's maybe possible to use an embedded language to implement the subsystem which are currently written in Matlab. This embedded language should feature: static/strong typing and compiler checks to minimize runtime errors small memory usage, and relative fast runtime attitude control algorithms are mainly numerical computations, so a good numeric support would be nice maybe some sort of functional programming feature, matlab/simulink encourage you to use it too I googled a bit, but only found Lua. It looks nice, but i would not use it in mission critical software. Have you ever encountered a situation like this, or do you know any language, which could satisfies the conditions? EDIT: To clarify some things: embedded means it should be able to embed the language into the existing c++ environment. So no compiled languages like Ada or Haskell ;)

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  • Java Spotlight Episode 89: Geoff Morton on Java Embedded

    - by Roger Brinkley
    Interview with Geoff Morton, Group Vice President, Worldwide Java Sales at Oracle , on Java embedded. Joining us this week on the Java All Star Developer Panel are Dalibor Topic, Java Free and Open Source Software Ambassador and Arun Gupta, Java EE Guy. Right-click or Control-click to download this MP3 file. You can also subscribe to the Java Spotlight Podcast Feed to get the latest podcast automatically. If you use iTunes you can open iTunes and subscribe with this link:  Java Spotlight Podcast in iTunes. Show Notes News EclipseLink 2.4 Hands-on FREE GlassFish Course NetBeans IDE 7.2 RC1 Hamish Morrison: OpenJDK Haiku port: quarter term report Proposed Update to the OpenJDK Web Site Terms of Use JavaOne Embedded Oracle Java ME Embedded Client (OJEC) 1.1 release on OTN New Videos Understanding the JVM and Low Latency Applications 55 New Things in Java 7 - Concurrency Events July 5, Java Forum, Stuttgart, Germany Jul 12, Java EE 6 workshop at Mindtree, Bangalore Jul 13-14, IndicThreads, Delhi July 30-August 1, JVM Language Summit, Santa Clara Feature InterviewGeoff Morton is the Group Vice President, Worldwide Java Sales at Oracle. Mail Bag What’s Cool Duke’s Choice Awards decision is going on Java Champions Facebook Page Joe Darcy: Moving monarchs and dragons: migrating the JDK bugs to JIRA Mike Duigou: Updated Lambda Binary Drops Mark Reinhold: Mercurial "jcheck" extension now available

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  • Moving From IT to Embedded software Developing

    - by Ameer Adel
    i worked for two years at a channel station, managing various Types of tasks, varying from printers installation, software solution, down to managing and maintaining server automation, to be honest, i always been enthusiastic about programming, i studied at some affordable college and finished my IT path successfully, my graduation project was in C# ADO.NET couple of years ago. Obviously it was so much of a beginner spaghetti code than a well furnished code. I also had the chance; after leaving the IT career, to study about some ASP.NET MVC and web apps development. I have rookie level of coding skills due to the poor level of education i endured, and sufficient resources. Currently i m working as a trainee in a newly opened embedded software development company, that is being said, i am, as i sound, have a little idea about the algorithms included, as i was reading for the past couple of days, embedded system development requires more strict coding skills, including memory management, CPU optimization according to its architect, and couple of other tricks regarding the display, and power management if mobile.. etc. My question is, What type of Algorithms am i supposed to use in such cases, as i mentioned before, i am really enthusiastic about learning programming skills and algorithms related to embedded systems and programming languages, including C/C++, Java, C#, and some EC++ if still operational.

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  • Grails GORM (Hibernate) query

    - by bsreekanth
    Hello, I'm trying to do the below sql statement in GORM select * from table1 where table1.x not in (select x from table 2 where y='something'); so, I have two tables, and needs to find the entries from table 1 which are not in table 2. In Grails def xx= table2.findByY('something') def c = table1.createCriteria() def result= c.list { not ( in('x', xx) ) } the syntax is wrong, and I'm not sure how to simulate not in sql logic. As a learning point, if someone can also tell me why minus (-) operator in grails/groovy doesn't work with list. I tried getting x and y seperately, and doing x.minus(y), but it doesn't change the list. I saw an explanation at http://stackoverflow.com/questions/1754576/groovy-on-grails-list-not-working , but I would expect the list defined are local. thank you so much.

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  • Efficiently retrieve objects with one to many references in Grails using GORM

    - by bebeastie
    I'm trying to determine how to find/retrieve/load objects efficiently in terms of a.) minimizing calls to database and b.) keeping the code as elegant/simple as possible (i.e. not writing hql etc.). Assume you have two objects: public class Foo { Bar bar String badge } public class Bar { String name } Each Foo has a bar and a badge. Also assume that all badges are unique within a bar. So if a Foo has a badge "4565" there are no other Foos that have the same badge # AND the same bar. If I have a bar ID, how can I efficiently retrive the Foo w/o first selecting Bar? I know I can do this: Foo.findByBadgeAndBar("4565", Bar.findById("1")) But that seems to cause a select on the Bar table followed by a select on the Foo table. In other words, I need to produce the Grails/Hibernate/GORM equivalent of the following: select * from foo where badge="4565" and bar_id="1"

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  • How do I do TDD on embedded devices?

    - by Darth
    I'm not new to programming and I've even worked with some low level C and ASM on AVR, but I really can't get my head around a larger-scale embedded C project. Being degenerated by the Ruby's philosophy of TDD/BDD, I'm unable to understand how people write and test code like this. I'm not saying it's a bad code, I just don't understand how this can work. I wanted to get more into some low level programming, but I really have no idea how to approach this, since it looks like a completely different mindset that I'm used to. I don't have trouble understanding pointer arithmetics, or how allocating memory works, but when I see how complex C/C++ code looks compared to Ruby, it just seems impossibly hard. Since I already ordered myself an Arduino board, I'd love to get more into some low level C and really understand how to do things properly, but it seems like none of the rules of high level languages apply. Is it even possible to do TDD on embedded devices or when developing drivers or things like custom bootloader, etc.?

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  • Skynet Big Data Demo Using Hexbug Spider Robot, Raspberry Pi, and Java SE Embedded (Part 4)

    - by hinkmond
    Here's the first sign of life of a Hexbug Spider Robot converted to become a Skynet Big Data model T-1. Yes, this is T-1 the precursor to the Cyberdyne Systems T-101 (and you know where that will lead to...) It is demonstrating a heartbeat using a simple Java SE Embedded program to drive it. See: Skynet Model T-1 Heartbeat It's alive!!! Well, almost alive. At least there's a pulse. We'll program more to its actions next, and then finally connect it to Skynet Big Data to do more advanced stuff, like hunt for Sara Connor. Java SE Embedded programming makes it simple to create the first model in the long line of T-XXX robots to take on the world. Raspberry Pi makes connecting it all together on one simple device, easy. Next post, I'll show how the wires are connected to drive the T-1 robot. Hinkmond

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  • embedded web browser

    - by Ilya
    Hi, I'm looking for Linux embedded web browser, or preferably just a rendering object (it will not be used for actual browsing, just for displaying web based gui). The requirements are: Written in C (small footprint) Support Dynamic HTML Support Java script Minimum dependencies on the libraries (although i understand that it can not be completely standalone) No Dependency on X11 (i.e working with direct frame qui libraries) So far i only found Embedded Konqueror. Any suggestions are welcomed, commercial solutions are OK, but open source is preferable.

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  • 50 Billion Served: Java Embedded on Devices

    - by Tori Wieldt
    It doesn't matter if it is 50 billion or 24 billion, just suffice it to stay that there will be MANY connected devices in the year 2020. With just 24 billion devices, they will outnumber humans six to one! So as a developer, you don't want to ignore this opportunity. What if you could use your Java skills and deploy an app to a fraction of these devices (don't be greedy, how about just, say, 118,000 of them)? Fareed Suliman, Java ME Product Manager had lots of good news for Java Developers in his presentation Modernizing the Explosion of Advanced Microcontrollers with Embedded Java at ARM TechCon in Santa Clara, CA last week. "A radical architecture shift is underway in this space, from proprietary to standards-based," he explained.  He pointed out several advantages to using Embedded Java for devices: Java is a proven and open standard. Java provides connectivity, encryption, location, and web services APIs. You don't have to focus on and keep reinventing the plumbing below the JVM. Abstracting the software from the hardware allows you to repeat your app across many devices. Abstracting the software from the hardware allows allows parallel development so you can get your app done more quickly. You already know Java (or you can hire lots of Java talent). Java is a full ecosystem, with Java Embedded plugins for IDEs like Eclipse and NetBeans. Java ME allows for in-field software upgrades. Suliman mentioned two ways developers can start using Java Embedded today:  Java ME Embedded Suite 7.0 Oracle Java Embedded Suite is a new packaged solution from Oracle (including Java DB, GlassFish for Embedded Suite, Jersey Web Services Framework, and Oracle Java SE Embedded 7 platform), created to provide value added services for collecting, managing, and transmitting data to embedded devices such as gateways and concentrators. Oracle Java ME Embedded 3.2 Oracle Java ME Embedded 3.2 is designed and optimized to meet the unique requirements of small embedded, low power devices such as micro-controllers and other resource-constrained hardware without screens or user interfaces. Think tiny. Really tiny. And think big.  Read more about Java Embedded at the Oracle Technology Network, and read The Java Source blog Java Embedded Releases from September.

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  • Oracle moves to Java technology to embedded middleware

    - by hinkmond
    Here's another article pointing out our move to Java Embedded Middleware with our launch of Oracle Java Embedded Suite 7.0 See: Oracle moves to Java embedded middleware Here's a quote: At the JavaOne Embedded conference, a wafer thin embedded device that was smaller than a Ritz cracker was loaded up with the Java Embedded Suite. I like that: "a wafer thin embedded device". Just one thin wafer. Reminds me of the scene from Monty Python's, The Meaning of Life. "Better?" Hinkmond

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  • What's the "best" database for embedded?

    - by mawg
    I'm an embedded guy, not a database guy. I've been asked to redesign an existing system which has bottlenecks in several places. The embedded device is based around an ARM 9 processor running at 220mHz. There should be a database of 50k entries (may increase to 250k) each with 1k of data (max 8 filed). That's approximate - I can try to get more precise figures if necessary. They are currently using SqlLite 2 and planning to move to SqlLite 3. Without starting a flame war - I am a complete d/b newbie just seeking advice - is that the "best" decision? I realize that this might be a "how long is a piece of string?" question, but any pointers woudl be greatly welcomed. I don't mind doing a lot of reading & research, but just hoped that you could get me off to a flying start. Thanks. p.s Again, a total rewrite, might not even stick with embedded Linux, but switch to eCos, don't worry too much about one time conversion between d/b formats. Oh, and accesses should be infrequent, at most one every few seconds. edit: ok, it seems they have 30k entries (may reach 100k or more) of only 5 or 6 fields each, but at least 3 of them can be a search key for a record. They are toying with "having no d/b at all, since the data are so simple", but it seems to me that with multiple keys, we couldn't use fancy stuff like a quicksort() type search (recursive, binary search). Any thoughts on "no d/b", just data-structures? Btw, one key is 800k - not sure how well SqlLite handles that (maybe with "no d/b" I have to hash that 800k to something smaller?)

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  • Embedded linux Development learning

    - by user1797375
    I come from a windows background and i am proficient with the .net platform. For work, i need to bring up a custom embedded system platform. We have bought the pandaboard ES as the test platform. The application is to stream images over the wifi. If you think about it, we are building something similar to a netgear router - the only difference being when you log into the device it serves images. Because my background is in windows i am not quite sure how to start off with embedded linux development. in reading through various sites i have come to the conclusion that going to linux as development host is the best option. Can some one point to me in the right direction regarding the set up. I have a windows machine that will be used for development purposes. I can either do a virtual box or setup a partition for linux. But the finer details are what throwing me off..what i need to know is 1) once i install linux what other software do I need - Code blocks, 2) what about toolchain 3) How to debug - through serial port ? 4) Is there a way to send the image built directly to the CF card? Thanks

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  • RPi and Java Embedded GPIO: Java code to blink more LEDs

    - by hinkmond
    Now, it's time to blink the other GPIO ports with the other LEDs connected to them. This is easy using Java Embedded, since the Java programming language is powerful and flexible. Embedded developers are not used to this, since the C programming language is more popular but less easy to develop in. We just need to use a dynamic Java String array to map to the pinouts of the GPIO port names from the previous diagram posted. This way we can address each "channel" with an index into that String array. static String[] GpioChannels = { "0", "1", "4", "17", "21", "22", "10", "9" }; With this new dynamic array, we can streamline the main() of this Java program to activate all the ports. /** * @param args the command line arguments */ public static void main(String[] args) { FileWriter[] commandChannels; try { /*** Init GPIO port for output ***/ // Open file handles to GPIO port unexport and export controls FileWriter unexportFile = new FileWriter("/sys/class/gpio/unexport"); FileWriter exportFile = new FileWriter("/sys/class/gpio/export"); for (String gpioChannel : GpioChannels) { System.out.println(gpioChannel); // Reset the port unexportFile.write(gpioChannel); unexportFile.flush(); // Set the port for use exportFile.write(gpioChannel); exportFile.flush(); // Open file handle to port input/output control FileWriter directionFile = new FileWriter("/sys/class/gpio/gpio" + gpioChannel + "/direction"); // Set port for output directionFile.write(GPIO_OUT); directionFile.flush(); } And, then simply add array code to where we blink the LED to make it blink all the LEDS on and off at once. /*** Send commands to GPIO port ***/ commandChannels = new FileWriter[GpioChannels.length]; for (int channum=0; channum It's easier than falling off a log... or at least easier than C programming. Hinkmond

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  • Advancing my Embedded knowledge.....with a CS degree.

    - by Mercfh
    So I graduated last December with a B.S. in Computer Science, in a pretty good well known engineering college. However towards the end I realized that I actually like Assembly/Lower level C programming more than I actually enjoy higher level abstracted OO stuff. (Like I Programmed my own Device Drivers for USB stuff in Linux, stuff like that) But.....I mean we really didn't concentrate much on that in college, perhaps an EE/CE degree would've been better, but I knew the classes......and things weren't THAT much different. I've messed around with Atmel AVR's/Arduino stuff (Mostly robotics) and Linux Kernals/Device Drivers. but I really want to enhance my skills and maybe one day get a job doing embedded stuff. (I have a job now, it's An entry level software dev/tester job, it's a good job but not exactly what my passion lies in) (Im pretty good with C and certain ASM's for specific microcontrollers) Is this even possible with a CS degree? or am I screwed? (since technically my degree usually doesn't involve much embedded stuff) If Im NOT screwed then what should I be studying/learning? How would I even go about it........ I guess I could eventually say "Experienced with XXXX Microcontrollers/ASM/etc...." but still, it wouldn't be the same as having a CE/EE degree. Also....going back to college isn't an option. just fyi. edit: Any book recommendations for "getting used to this stuff" I have ARM System-on-Chip Architecture (2nd edition) it's good.....for ARM stuff lol

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  • Freescale One Box Unboxing (then installing Java SE Embedded technology)

    - by hinkmond
    So, I get a FedEx delivery the other day... "What cool device could be inside this FedEx Overnight Express Large Box?" I was wondering... Could it be a new Linux/ARM target device board, faster than a Raspberry Pi and better than a BeagleBone Black??? Why, yes! Yes, it was a Linux/ARM target device board, faster than anything around! It was a Freescale i.MX6 Sabre Smart Device Board (SDB)! Cool... Quad Core ARM Cortex A9 1GHz with 1GB of RAM. So, cool... I installed the Freescale One Box OpenWRT Linux image onto its SD card and booted it up into Linux. But, wait! One thing was missing... What was it? What could be missing? Why, it had no Java SE Embedded installed on it yet, of course! So, I went to the JDK 7u45 download link. Clicked on "Accept License Agreement", and clicked on "jdk-7u45-linux-arm-vfp-sflt.tar.gz", installed the bad boy, and all was good. Java SE Embedded 7u45 on a Freescale One Box. Nice... Hinkmond

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  • Languages on embedded systems in aeronautic and spatial sector

    - by Niels
    I know that my question is very broad but a general answer would be nice. I would like to know which are the main languages used in aeronautic and spatial sector. I know that the OS which run on embedded systems are RTOS (Real time OS) and I think that, this languages must be checked correctly by different methods (formal methods, unit tests) and must permit a sure verification of whole process of a program.

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  • Java SE Embedded-Enabled Raspberry Pi Ice Bucket Challenge

    - by hinkmond
    Help fight ALS at: http://www.alsa.org/fight-als/ See: Java SE Embedded-Enabled Raspberry Pi Ice Bucket Challenge My Java SE Enabled Raspberry Pi accepts the nomination for the ALS Ice Bucket Challenge and I hereby nominate the Nest thermostat, the Fitbit fitness tracker, and Apple TV. Take the Ice Bucket Challenge. Help find the cure for ALS: http://www.alsa.org/fight-als/ice-bucket-challenge.html Hinkmond

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  • RPi and Java Embedded GPIO: It all begins with hardware

    - by hinkmond
    So, you want to connect low-level peripherals (like blinky-blinky LEDs) to your Raspberry Pi and use Java Embedded technology to program it, do you? You sick foolish masochist. No, just kidding! That's awesome! You've come to the right place. I'll step you though it. And, as with many embedded projects, it all begins with hardware. So, the first thing to do is to get acquainted with the GPIO header on your RPi board. A "header" just means a thingy with a bunch of pins sticking up from it where you can connect wires. See the the red box outline in the photo. Now, there are many ways to connect to that header outlined by the red box in the photo (which the RPi folks call the P1 header). One way is to use a breakout kit like the one at Adafruit. But, we'll just use jumper wires in this example. So, to connect jumper wires to the header you need a map of where to connect which wire. That's why you need to study the pinout in the photo. That's your map for connecting wires. But, as with many things in life, it's not all that simple. RPi folks have made things a little tricky. There are two revisions of the P1 header pinout. One for older boards (RPi boards made before Sep 2012), which is called Revision 1. And, one for those fancy 512MB boards that were shipped after Sep 2012, which is called Revision 2. So, first make sure which board you have: either you have the Model A or B with 128MB or 256MB built before Sep 2012 and you need to look at the pinout for Rev. 1, or you have the Model B with 512MB and need to look at Rev. 2. That's all you need for now. More to come... Hinkmond

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  • Better Embedded 2013

    - by Valter Minute
    Originally posted on: http://geekswithblogs.net/WindowsEmbeddedCookbook/archive/2013/07/30/better-embedded-2013.aspx On July 8th and 9th I had a chance to attend and speak at the Better Embedded 2013 conference in Florence. Visiting Florence is always a pleasure, but having a chance to attend to such an interesting conference and to meet Marco Dal Pino, Paolo Patierno, Mirco Vanini and many other embedded developers made those two days an experience to be remembered. I did two sessions, one on Windows Embedded Standard and “PCs” usage in the embedded world and another one on Android for Embedded devices, you can find the slides on the better embedded website: www.betterembedded.it. You can also find slides for many other interesting session, ranging from the .NET microframework to Linux Embedded, from QT Quick to software licenses. Packing many different resources about embedded systems in a conference was not easy but the result is a very nice mix of contents ranging from firmware development to cloud-based systems. This is a great way to have an overview of what’s new or interesting in embedded systems and to get great ideas about how to build your new device. Don’t forget to follow @Better_Embedded on twitter to not miss next year conference! Thanks to the better embedded team for having allowed me to use some of the official pictures in this blog post. You can find a good selection of those pictures (just to experience the atmosphere of the conference) on its Facebook page: http://dvlr.it/DHDB

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  • Videos: Getting Started with Java Embedded

    - by Tori Wieldt
    Are you a Java developer? That means you can write applications for embedded processors! There are new six new videos up on the YouTube/Java channel that you can watch to get more information. To get an overview, watch James Allen of Oracle Global Business Development give OTN a tour of the Oracle booth at ARM Techcon. He also explains the huge opportunity for Java in the embedded space. These videos from Oracle Engineering show you how to leverage your knowledge to seamlessly develop in a space that is really taking off. Java SE Embedded Development Made Easy, Part 1 This video demonstrates how developers already familiar with the Java SE development paradigm can leverage their knowledge to seamlessly develop on very capable embedded processors. Part one of a two-part series. Java SE Embedded Development Made Easy, Part 2 This video demonstrates how developers already familiar with the Java SE development paradigm can leverage their knowledge to seamlessly develop on very capable embedded processors. Part two of a two-part series. Mobile Database Synchronization - Healthcare Demonstration This video demonstrates how a good portion of Oracle's embedded technologies (Java SE-Embedded, Berkeley DB, Database Mobile Server) can be applied to a medical application. Tomcat Micro Cluster See how multiple embedded devices installed with Java Standard Edition HotSpot for Armv5/Linux and Apache Tomcat can be configured as a micro cluster. Java Embedded Partnerships Kevin Smith of Oracle Technical Business Development explains what's new for partners and Java developers in the embedded space. Learn how you can start prototyping for Qualcomm's new Orion board before it's available. (Sorry about the video quality, the booth lights were weird.)   Visit the YouTube/Java channel for other great Java videos. <fade to black>

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  • RPi and Java Embedded GPIO: Writing Java code to blink LED

    - by hinkmond
    So, you've followed the previous steps to install Java Embedded on your Raspberry Pi ?, you went to Fry's and picked up some jumper wires, LEDs, and resistors ?, you hooked up the wires, LED, and resistor the the correct pins ?, and now you want to start programming in Java on your RPi? Yes? ???????! OK, then... Here we go. You can use the following source code to blink your first LED on your RPi using Java. In the code you can see that I'm not using any complicated gpio libraries like wiringpi or pi4j, and I'm not doing any low-level pin manipulation like you can in C. And, I'm not using python (hell no!). This is Java programming, so we keep it simple (and more readable) than those other programming languages. See: Write Java code to do this In the Java code, I'm opening up the RPi Debian Wheezy well-defined file handles to control the GPIO ports. First I'm resetting everything using the unexport/export file handles. (On the RPi, if you open the well-defined file handles and write certain ASCII text to them, you can drive your GPIO to perform certain operations. See this GPIO reference). Next, I write a "1" then "0" to the value file handle of the GPIO0 port (see the previous pinout diagram). That makes the LED blink. Then, I loop to infinity. Easy, huh? import java.io.* /* * Java Embedded Raspberry Pi GPIO app */ package jerpigpio; import java.io.FileWriter; /** * * @author hinkmond */ public class JerpiGPIO { static final String GPIO_OUT = "out"; static final String GPIO_ON = "1"; static final String GPIO_OFF = "0"; static final String GPIO_CH00="0"; /** * @param args the command line arguments */ public static void main(String[] args) { FileWriter commandFile; try { /*** Init GPIO port for output ***/ // Open file handles to GPIO port unexport and export controls FileWriter unexportFile = new FileWriter("/sys/class/gpio/unexport"); FileWriter exportFile = new FileWriter("/sys/class/gpio/export"); // Reset the port unexportFile.write(GPIO_CH00); unexportFile.flush(); // Set the port for use exportFile.write(GPIO_CH00); exportFile.flush(); // Open file handle to port input/output control FileWriter directionFile = new FileWriter("/sys/class/gpio/gpio"+GPIO_CH00+"/direction"); // Set port for output directionFile.write(GPIO_OUT); directionFile.flush(); /*--- Send commands to GPIO port ---*/ // Opne file handle to issue commands to GPIO port commandFile = new FileWriter("/sys/class/gpio/gpio"+GPIO_CH00+"/value"); // Loop forever while (true) { // Set GPIO port ON commandFile.write(GPIO_ON); commandFile.flush(); // Wait for a while java.lang.Thread.sleep(200); // Set GPIO port OFF commandFile.write(GPIO_OFF); commandFile.flush(); // Wait for a while java.lang.Thread.sleep(200); } } catch (Exception exception) { exception.printStackTrace(); } } } Hinkmond

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  • RPi and Java Embedded GPIO: Sensor Reading using Java Code

    - by hinkmond
    And, now to program the Java code for reading the fancy-schmancy static electricity sensor connected to your Raspberry Pi, here is the source code we'll use: First, we need to initialize ourselves... /* * Java Embedded Raspberry Pi GPIO Input app */ package jerpigpioinput; import java.io.FileWriter; import java.io.RandomAccessFile; import java.text.DateFormat; import java.text.SimpleDateFormat; import java.util.Calendar; /** * * @author hinkmond */ public class JerpiGPIOInput { static final String GPIO_IN = "in"; // Add which GPIO ports to read here static String[] GpioChannels = { "7" }; /** * @param args the command line arguments */ public static void main(String[] args) { try { /*** Init GPIO port(s) for input ***/ // Open file handles to GPIO port unexport and export controls FileWriter unexportFile = new FileWriter("/sys/class/gpio/unexport"); FileWriter exportFile = new FileWriter("/sys/class/gpio/export"); for (String gpioChannel : GpioChannels) { System.out.println(gpioChannel); // Reset the port unexportFile.write(gpioChannel); unexportFile.flush(); // Set the port for use exportFile.write(gpioChannel); exportFile.flush(); // Open file handle to input/output direction control of port FileWriter directionFile = new FileWriter("/sys/class/gpio/gpio" + gpioChannel + "/direction"); // Set port for input directionFile.write(GPIO_IN); directionFile.flush(); } And, next we will open up a RandomAccessFile pointer to the GPIO port. /*** Read data from each GPIO port ***/ RandomAccessFile[] raf = new RandomAccessFile[GpioChannels.length]; int sleepPeriod = 10; final int MAXBUF = 256; byte[] inBytes = new byte[MAXBUF]; String inLine; int zeroCounter = 0; // Get current timestamp with Calendar() Calendar cal; DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss.SSS"); String dateStr; // Open RandomAccessFile handle to each GPIO port for (int channum=0; channum Then, loop forever to read in the values to the console. // Loop forever while (true) { // Get current timestamp for latest event cal = Calendar.getInstance(); dateStr = dateFormat.format(cal.getTime()); // Use RandomAccessFile handle to read in GPIO port value for (int channum=0; channum Rinse, lather, and repeat... Compile this Java code on your host PC or Mac with javac from the JDK. Copy over the JAR or class file to your Raspberry Pi, "sudo -i" to become root, then start up this Java app in a shell on your RPi. That's it! You should see a "1" value get logged each time you bring a statically charged item (like a balloon you rub on the cat) near the antenna of the sensor. There you go. You've just seen how Java Embedded technology on the Raspberry Pi is an easy way to access sensors. Hinkmond

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  • Web application framework for embedded systems?

    - by datenwolf
    I'm currently developing the software for a measurement and control system. In addition to the usual SCPI interface I'd also give it a nice HTTP frontend. Now I don't want to reinvent the wheel all over again. I already have a simple HTTPD running, but I don't want to implement all the other stuff. So what I'm looking for is a web application toolkit targeted at embedded system development. In particular this has to run on a ARM Cortex-M4, and I have some 8k of RAM available for this. It must be written in C. Is there such a thing or do I have to implement this myself?

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