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• How to Run Low-Cost Minecraft on a Raspberry Pi for Block Building on the Cheap

  - by Jason Fitzpatrick

  We’ve shown you how to run your own blocktastic personal Minecraft server on a Windows/OSX box, but what if you crave something lighter weight, more energy efficient, and always ready for your friends? Read on as we turn a tiny Raspberry Pi machine into a low-cost Minecraft server you can leave on 24/7 for around a penny a day. Why Do I Want to Do This? There’s two aspects to this tutorial, running your own Minecraft server and specifically running that Minecraft server on a Raspberry Pi. Why would you want to run your own Minecraft server? It’s a really great way to extend and build upon the Minecraft play experience. You can leave the server running when you’re not playing so friends and family can join and continue building your world. You can mess around with game variables and introduce mods in a way that isn’t possible when you’re playing the stand-alone game. It also gives you the kind of control over your multiplayer experience that using public servers doesn’t, without incurring the cost of hosting a private server on a remote host. While running a Minecraft server on its own is appealing enough to a dedicated Minecraft fan, running it on the Raspberry Pi is even more appealing. The tiny little Pi uses so little resources that you can leave your Minecraft server running 24/7 for a couple bucks a year. Aside from the initial cost outlay of the Pi, an SD card, and a little bit of time setting it up, you’ll have an always-on Minecraft server at a monthly cost of around one gumball. What Do I Need? For this tutorial you’ll need a mix of hardware and software tools; aside from the actual Raspberry Pi and SD card, everything is free. 1 Raspberry Pi (preferably a 512MB model) 1 4GB+ SD card This tutorial assumes that you have already familiarized yourself with the Raspberry Pi and have installed a copy of the Debian-derivative Raspbian on the device. If you have not got your Pi up and running yet, don’t worry! Check out our guide, The HTG Guide to Getting Started with Raspberry Pi, to get up to speed. Optimizing Raspbian for the Minecraft Server Unlike other builds we’ve shared where you can layer multiple projects over one another (e.g. the Pi is more than powerful enough to serve as a weather/email indicator and a Google Cloud Print server at the same time) running a Minecraft server is a pretty intense operation for the little Pi and we’d strongly recommend dedicating the entire Pi to the process. Minecraft seems like a simple game, with all its blocky-ness and what not, but it’s actually a pretty complex game beneath the simple skin and required a lot of processing power. As such, we’re going to tweak the configuration file and other settings to optimize Rasbian for the job. The first thing you’ll need to do is dig into the Raspi-Config application to make a few minor changes. If you’re installing Raspbian fresh, wait for the last step (which is the Raspi-Config), if you already installed it, head to the terminal and type in “sudo raspi-config” to launch it again. One of the first and most important things we need to attend to is cranking up the overclock setting. We need all the power we can get to make our Minecraft experience enjoyable. In Raspi-Config, select option number 7 “Overclock”. Be prepared for some stern warnings about overclocking, but rest easy knowing that overclocking is directly supported by the Raspberry Pi foundation and has been included in the configuration options since late 2012. Once you’re in the actual selection screen, select “Turbo 1000MhHz”. Again, you’ll be warned that the degree of overclocking you’ve selected carries risks (specifically, potential corruption of the SD card, but no risk of actual hardware damage). Click OK and wait for the device to reset. Next, make sure you’re set to boot to the command prompt, not the desktop. Select number 3 “Enable Boot to Desktop/Scratch”  and make sure “Console Text console” is selected. Back at the Raspi-Config menu, select number 8 “Advanced Options’. There are two critical changes we need to make in here and one option change. First, the critical changes. Select A3 “Memory Split”: Change the amount of memory available to the GPU to 16MB (down from the default 64MB). Our Minecraft server is going to ruin in a GUI-less environment; there’s no reason to allocate any more than the bare minimum to the GPU. After selecting the GPU memory, you’ll be returned to the main menu. Select “Advanced Options” again and then select A4 “SSH”. Within the sub-menu, enable SSH. There is very little reason to keep this Pi connected to a monitor and keyboard, by enabling SSH we can remotely access the machine from anywhere on the network. Finally (and optionally) return again to the “Advanced Options” menu and select A2 “Hostname”. Here you can change your hostname from “raspberrypi” to a more fitting Minecraft name. We opted for the highly creative hostname “minecraft”, but feel free to spice it up a bit with whatever you feel like: creepertown, minecraft4life, or miner-box are all great minecraft server names. That’s it for the Raspbian configuration tab down to the bottom of the main screen and select “Finish” to reboot. After rebooting you can now SSH into your terminal, or continue working from the keyboard hooked up to your Pi (we strongly recommend switching over to SSH as it allows you to easily cut and paste the commands). If you’ve never used SSH before, check out how to use PuTTY with your Pi here. Installing Java on the Pi The Minecraft server runs on Java, so the first thing we need to do on our freshly configured Pi is install it. Log into your Pi via SSH and then, at the command prompt, enter the following command to make a directory for the installation: sudo mkdir /java/ Now we need to download the newest version of Java. At the time of this publication the newest release is the OCT 2013 update and the link/filename we use will reflect that. Please check for a more current version of the Linux ARMv6/7 Java release on the Java download page and update the link/filename accordingly when following our instructions. At the command prompt, enter the following command: sudo wget --no-check-certificate http://www.java.net/download/jdk8/archive/b111/binaries/jdk-8-ea-b111-linux-arm-vfp-hflt-09_oct_2013.tar.gz Once the download has finished successfully, enter the following command: sudo tar zxvf jdk-8-ea-b111-linux-arm-vfp-hflt-09_oct_2013.tar.gz -C /opt/ Fun fact: the /opt/ directory name scheme is a remnant of early Unix design wherein the /opt/ directory was for “optional” software installed after the main operating system; it was the /Program Files/ of the Unix world. After the file has finished extracting, enter: sudo /opt/jdk1.8.0/bin/java -version This command will return the version number of your new Java installation like so: java version "1.8.0-ea" Java(TM) SE Runtime Environment (build 1.8.0-ea-b111) Java HotSpot(TM) Client VM (build 25.0-b53, mixed mode) If you don’t see the above printout (or a variation thereof if you’re using a newer version of Java), try to extract the archive again. If you do see the readout, enter the following command to tidy up after yourself: sudo rm jdk-8-ea-b111-linux-arm-vfp-hflt-09_oct_2013.tar.gz At this point Java is installed and we’re ready to move onto installing our Minecraft server! Installing and Configuring the Minecraft Server Now that we have a foundation for our Minecraft server, it’s time to install the part that matter. We’ll be using SpigotMC a lightweight and stable Minecraft server build that works wonderfully on the Pi. First, grab a copy of the the code with the following command: sudo wget http://ci.md-5.net/job/Spigot/lastSuccessfulBuild/artifact/Spigot-Server/target/spigot.jar This link should remain stable over time, as it points directly to the most current stable release of Spigot, but if you have any issues you can always reference the SpigotMC download page here. After the download finishes successfully, enter the following command: sudo /opt/jdk1.8.0/bin/java -Xms256M -Xmx496M -jar /home/pi/spigot.jar nogui Note: if you’re running the command on a 256MB Pi change the 256 and 496 in the above command to 128 and 256, respectively. Your server will launch and a flurry of on-screen activity will follow. Be prepared to wait around 3-6 minutes or so for the process of setting up the server and generating the map to finish. Future startups will take much less time, around 20-30 seconds. Note: If at any point during the configuration or play process things get really weird (e.g. your new Minecraft server freaks out and starts spawning you in the Nether and killing you instantly), use the “stop” command at the command prompt to gracefully shutdown the server and let you restart and troubleshoot it. After the process has finished, head over to the computer you normally play Minecraft on, fire it up, and click on Multiplayer. You should see your server: If your world doesn’t popup immediately during the network scan, hit the Add button and manually enter the address of your Pi. Once you connect to the server, you’ll see the status change in the server status window: According to the server, we’re in game. According to the actual Minecraft app, we’re also in game but it’s the middle of the night in survival mode: Boo! Spawning in the dead of night, weaponless and without shelter is no way to start things. No worries though, we need to do some more configuration; no time to sit around and get shot at by skeletons. Besides, if you try and play it without some configuration tweaks first, you’ll likely find it quite unstable. We’re just here to confirm the server is up, running, and accepting incoming connections. Once we’ve confirmed the server is running and connectable (albeit not very playable yet), it’s time to shut down the server. Via the server console, enter the command “stop” to shut everything down. When you’re returned to the command prompt, enter the following command: sudo nano server.properties When the configuration file opens up, make the following changes (or just cut and paste our config file minus the first two lines with the name and date stamp): #Minecraft server properties #Thu Oct 17 22:53:51 UTC 2013 generator-settings= #Default is true, toggle to false allow-nether=false level-name=world enable-query=false allow-flight=false server-port=25565 level-type=DEFAULT enable-rcon=false force-gamemode=false level-seed= server-ip= max-build-height=256 spawn-npcs=true white-list=false spawn-animals=true texture-pack= snooper-enabled=true hardcore=false online-mode=true pvp=true difficulty=1 player-idle-timeout=0 gamemode=0 #Default 20; you only need to lower this if you're running #a public server and worried about loads. max-players=20 spawn-monsters=true #Default is 10, 3-5 ideal for Pi view-distance=5 generate-structures=true spawn-protection=16 motd=A Minecraft Server In the server status window, seen through your SSH connection to the pi, enter the following command to give yourself operator status on your Minecraft server (so that you can use more powerful commands in game, without always returning to the server status window). op [your minecraft nickname] At this point things are looking better but we still have a little tweaking to do before the server is really enjoyable. To that end, let’s install some plugins. The first plugin, and the one you should install above all others, is NoSpawnChunks. To install the plugin, first visit the NoSpawnChunks webpage and grab the download link for the most current version. As of this writing the current release is v0.3. Back at the command prompt (the command prompt of your Pi, not the server console–if your server is still active shut it down) enter the following commands: cd /home/pi/plugins sudo wget http://dev.bukkit.org/media/files/586/974/NoSpawnChunks.jar Next, visit the ClearLag plugin page, and grab the latest link (as of this tutorial, it’s v2.6.0). Enter the following at the command prompt: sudo wget http://dev.bukkit.org/media/files/743/213/Clearlag.jar Because the files aren’t compressed in a .ZIP or similar container, that’s all there is to it: the plugins are parked in the plugin directory. (Remember this for future plugin downloads, the file needs to be whateverplugin.jar, so if it’s compressed you need to uncompress it in the plugin directory.) Resart the server: sudo /opt/jdk1.8.0/bin/java -Xms256M -Xmx496M -jar /home/pi/spigot.jar nogui Be prepared for a slightly longer startup time (closer to the 3-6 minutes and much longer than the 30 seconds you just experienced) as the plugins affect the world map and need a minute to massage everything. After the spawn process finishes, type the following at the server console: plugins This lists all the plugins currently active on the server. You should see something like this: If the plugins aren’t loaded, you may need to stop and restart the server. After confirming your plugins are loaded, go ahead and join the game. You should notice significantly snappier play. In addition, you’ll get occasional messages from the plugins indicating they are active, as seen below: At this point Java is installed, the server is installed, and we’ve tweaked our settings for for the Pi.  It’s time to start building with friends!     

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• The Raspberry Pi Now Has Its Own App Store

  - by Jason Fitzpatrick

  Raspberry Pi, the credit-card sized computer with an ARM processor, now has its own appstore where Raspberry Pi hobbyists and developers can share their creations in a one-stop location accessible to all Raspberry Pi users. In today’s press release about the store, the Raspberry Pi Foundation writes: We’ve been amazed by the variety of software that people have written for, or ported to, the Raspberry Pi. Today, together with our friends at IndieCity and Velocix, we’re launching the Pi Store to make it easier for developers of all ages to share their games, applications, tools and tutorials with the rest of the community. The Pi Store will, we hope, become a one-stop shop for all your Raspberry Pi needs; it’s also an easier way into the Raspberry Pi experience for total beginners, who will find everything they need to get going in one place, for free. The store runs as an X application under Raspbian, and allows users to download content, and to upload their own content for moderation and release. At launch, we have 23 free titles in the store, ranging from utilities like LibreOffice and Asterisk to classic games like Freeciv and OpenTTD and Raspberry Pi exclusive Iridium Rising. We also have one piece of commercial content: the excellent Storm in a Teacup from Cobra Mobile. For more information about the store, including how to install the app store on your Pi, check out the full press release here. To get started browsing the store, hit up the link below. Secure Yourself by Using Two-Step Verification on These 16 Web Services How to Fix a Stuck Pixel on an LCD Monitor How to Factory Reset Your Android Phone or Tablet When It Won’t Boot

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• ???Past Image(pi)

  - by todd.bao(at)oracle.com

  Past Image???RAC??????????,????????????????????????????????,Past Image??????????,?????????????????,?????????????????,??????????????(pi)?????????????????Past Image,????????????:HR.EMPLOYEES??100????101?????5????88???????????????,???????????# ??1: ?????????SYS@RAC1//scripts> select inst_id,status from gv$bh where file#=5 and block#=88;no rows selected# ??1???(???Steve King, ????24000????)SYS@RAC1//scripts> update hr.employees set salary=1 where employee_id=100;1 row updated.# ??2: ????1??xcur????????????,?????????SYS@RAC1//scripts> select inst_id,dirty,status from gv$bh where file#=5 and  block#=88;   INST_ID + D + STATUS---------- + - + -------         1 + Y + xcur1 row selected.# ??2???SYS@RAC2//scripts> update hr.employees set salary=2 where employee_id=101;1 row updated.# ??3: ????2?,?????1??pi??Past Image,???????????????????????SYS@RAC1//scripts> select inst_id,dirty,status from gv$bh where file#=5 and  block#=88;   INST_ID + D + STATUS---------- + - + -------         1 + Y + pi         2 + Y + xcur2 rows selected.# ??1???SYS@RAC1//scripts> update hr.employees set salary=3 where employee_id=100;1 row updated.# ??4: ????1?,?????2???1???????2???????1???????SYS@RAC1//scripts> select inst_id,dirty,status from gv$bh where file#=5 and  block#=88;   INST_ID + D + STATUS---------- + - + -------         1 + Y + pi         1 + Y + xcur         2 + Y + pi3 rows selected.# ??2????SYS@RAC2//scripts> update hr.employees set salary=4 where employee_id=101;1 row updated.# ??5: ????2?,??????????????,DBWR??,??????,??(pi)?????????????(cr)??????????????????????????SYS@RAC1//scripts> select inst_id,dirty,status from gv$bh where file#=5 and  block#=88;   INST_ID + D + STATUS---------- + - + -------         1 + N + cr         1 + N + cr         2 + Y + xcur3 rows selected.# ?????1???SYS@RAC1//scripts> update hr.employees set salary=5 where employee_id=100;1 row updated.# ??6: ????1?,?????2????????????????,?????????SYS@RAC1//scripts> select inst_id,dirty,status from gv$bh where file#=5 and  block#=88;   INST_ID + D + STATUS---------- + - + -------         1 + Y + xcur         1 + N + cr         1 + N + cr         2 + Y + pi4 rows selected.# ??2???SYS@RAC2//scripts> update hr.employees set salary=6 where employee_id=101;1 row updated.# ??7: ????2?,?????1?2????1???????2?????????????4,????????????????SYS@RAC1//scripts> select inst_id,dirty,status from gv$bh where file#=5 and  block#=88;   INST_ID + D + STATUS---------- + - + -------         1 + Y + pi         2 + Y + pi         2 + Y + xcur3 rows selected.# ??1???SYS@RAC1//scripts> update hr.employees set salary=7 where employee_id=100;1 row updated.# ??8: ????1?,?????2?1????2???????1????????????2????????????????????????????????????(????????)????SYS@RAC1//scripts> select inst_id,dirty,status from gv$bh where file#=5 and  block#=88;   INST_ID + D + STATUS---------- + - + -------         1 + Y + pi         1 + Y + xcur         2 + Y + pi         2 + N + cr4 rows selected.??????????, ?xcur??????????:??????xcur????pi?????pi?(?????)???cr?,???cr?????,pi????????????????????????????:?????????????A?B?A:SYS@RAC1//scripts> run  1  begin  2  for i in 1..100000 loop  3  update hr.employees set salary=i where employee_id=100;  4  end loop;  5* end;B:SYS@RAC2//scripts> run  1  begin  2  for i in 1..100000 loop  3  update hr.employees set salary=i where employee_id=101;  4  end loop;  5* end;?????????,???5???88?????buffer cache???????:SYS@RAC2//scripts> select count(*) from gv$bh where file#=5 and block#=88;  COUNT(*)----------       4121 row selected.??409?????????(cur):SYS@RAC2//scripts> select count(*) from gv$bh where file#=5 and block#=88 where status='cr';  COUNT(*)----------       4091 row selected.1????????(xcur):SYS@RAC2//scripts> select count(*) from gv$bh where file#=5 and block#=88 where status='xcur';  COUNT(*)----------           11 row selected.??...2??????--????(pi)??????????SYS@RAC1//scripts> select inst_id,dirty,status from gv$bh where file#=5 and block#=88 and status='pi';   INST_ID + D + STATUS---------- + - + -------         1 + Y + pi         2 + Y + pi2 rows selected.????,???RAC??????????????(cr)?,????????????????????????xcur?pi??cr??????pi?????? ?????????,???????????pi???cr?,?????????cr???,???xcur???????,pi??????xcur?,[email protected]

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• Super Computer Built from Raspberry Pi Boards and LEGO Bricks

  - by Jason Fitzpatrick

  It was only a matter of time before someone chained together dozens of Raspberry Pi boards into a serviceable super computer; read on to see how a team of Southampton scientists built a 64-core machine using them. Image courtesy of Simon Cox and the University of Southampton. From the University of South Hampton press release: Professor Cox comments: “As soon as we were able to source sufficient Raspberry Pi computers we wanted to see if it was possible to link them together into a supercomputer. We installed and built all of the necessary software on the Pi starting from a standard Debian Wheezy system image and we have published a guide so you can build your own supercomputer.” The racking was built using Lego with a design developed by Simon and James, who has also been testing the Raspberry Pi by programming it using free computer programming software Python and Scratch over the summer. The machine, named “Iridis-Pi” after the University’s Iridis supercomputer, runs off a single 13 Amp mains socket and uses MPI (Message Passing Interface) to communicate between nodes using Ethernet. The whole system cost under £2,500 (excluding switches) and has a total of 64 processors and 1Tb of memory (16Gb SD cards for each Raspberry Pi). Professor Cox uses the free plug-in ‘Python Tools for Visual Studio’ to develop code for the Raspberry Pi. How to Get Pro Features in Windows Home Versions with Third Party Tools HTG Explains: Is ReadyBoost Worth Using? HTG Explains: What The Windows Event Viewer Is and How You Can Use It

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• Raspberry Pi entrance signed backed by Umbraco - Part 1

  - by Chris Houston

  Being experts on all things Umbraco, we jumped at the chance to help our client, QV Offices, with their pressing signage predicament. They needed to display a sign in the entrance to their building and approached us for our advice. Of course it had to be electronic: displaying multiple names of their serviced office clients, meeting room bookings and on-the-pulse promotions. But with a winding Victorian staircase and minimal storage space how could the monitor be run, updated and managed? That’s where we came in…Raspberry PiUmbraco CMSAutomatic updatesAutomated monitor of the signPower saving when the screen is not in useMounting the screenThe screen that has been used is a standard LED low energy Full HD screen and has been mounted on the wall using it's VESA mounting points, as the wall is a stud wall we were able to add an access panel behind the screen to feed through the mains, HDMI and sensor cables.The Raspberry Pi is then tucked away out of sight in the main electrical cupboard which just happens to be next to the sign, we had an electrician add a power point inside this cupboard to allow us to power the screen and the Raspberry Pi.Designing the interface and editing the contentAlthough a room sign was the initial requirement from QV Offices, their medium term goal has always been to add online meeting booking to their website and hence we suggested adding information about the current and next day's meetings to the sign that would be pulled directly from their online booking system.We produced the design and built the web page to fit exactly on a 1920 x 1080 screen (Full HD in Portrait)As you would expect all the information can be edited via an Umbraco CMS, they are able to add floors, rooms, clients and virtual clients as well as add meeting bookings to their meeting diary.How we configured the Raspberry PiAfter receiving a new Raspberry Pi we downloaded the latest release of Raspbian operating system and followed the official guide which shows how to copy the OS onto an SD card from a Mac, we then followed the majority of steps on this useful guide: 10 Things to Do After Buying a Raspberry Pi.Installing ChromiumWe chose to use the Chromium web browser which for those who do not know is the open sourced version of Google Chrome. You can install this from the terminal with the following command:sudo apt-get install chromium-browserInstalling UnclutterWe found this little application which automatically hides the mouse pointer, it is used in the script below and is installed using the following command:sudo apt-get install unclutterAuto start Chromium and disabling the screen saver, power saving and mouseWhen the Raspberry Pi has been installed it will not have a keyboard or mouse and hence if their was a power cut we needed it to always boot and re-loaded Chromium with the correct URL.Our preferred command line text editor is Nano and I have assumed you know how to use this editor or will be able to work it out pretty quickly.So using the following command:sudo nano /etc/xdg/lxsession/LXDE/autostartWe then changed the autostart file content to:@lxpanel --profile LXDE@pcmanfm --desktop --profile LXDE@xscreensaver -no-splash@xset s off@xset -dpms@xset s noblank@chromium --kiosk --incognito http://www.qvoffices.com/someURL@unclutter -idle 0The first few commands turn off the screen saver and power saving, we then open Cromium in Kiosk Mode (full screen with no menu etc) and pass in the URL to use (I have changed the URL in this example) We found a useful blog post with the Cromium command line switches.Finally we also open an application called Unclutter which auto hides the mouse after 0 seconds, so you will never see a mouse on the sign.We also had to edit the following file:sudo nano /etc/lightdm/lightdm.confAnd added the following line under the [SeatDefault] section:xserver-command=X -s 0 dpmsRefreshing the screenWe decided to try and add a scheduled task that would trigger Chromium to reload the page, at some point in the future we might well change this to using Javascript to update the content, but for now this works fine.First we installed the XDOTool which enables you to script Keyboard commands:sudo apt-get install xdotoolWe used the Refreshing Chromium Browser by Shell Script post as a reference and created the following shell script (which we called refreshing.sh):export DISPLAY=":0"WID=$(xdotool search --onlyvisible --class chromium|head -1)xdotool windowactivate ${WID}xdotool key ctrl+F5This selects the correct display and then sends a CTRL + F5 to refresh Chromium.You will need to give this file execute permissions:chmod a=rwx refreshing.shNow we have the script file setup we just need to schedule it to call this script periodically which is done by using Crontab, to edit this you use the following command:crontab -eAnd we added the following:*/5 * * * * DISPLAY=":.0" /home/pi/scripts/refreshing.sh >/home/pi/cronlog.log 2>&1This calls our script every 5 minutes to refresh the display and it logs any errors to the cronlog.log file.SummaryQV Offices now have a richer and more manageable booking system than they did before we started, and a great new sign to boot.How could we make sure that the sign was running smoothly downstairs in a busy office centre? A second post will follow outlining exactly how Vizioz enabled QV Offices to monitor their sign simply and remotely, from the comfort of their desks.

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• Solar Case Mod Powers Raspberry Pi FTP Server with Sunshine

  - by Jason Fitzpatrick

  This project combines a solar panel, Raspberry Pi, and a bit of code for the Pi to turn the whole array into a solar powered server (you could easily modify the project to become a solar powered music player or other device). The case mod comes to us courtesy of tinker CottonPickers–he shares the build and offers the cases for sale here. Building off the solar case, David Hayward at CNET UK added on an FTP server so that the Pi can serve as a tiny, take-anywhere, power-outlet optional, file sharing hub. Hit up the link below for the FTP configuration instructions. How to Make a Raspberry Pi Solar-Powered FTP Server [CNET UK] How to Fix a Stuck Pixel on an LCD Monitor How to Factory Reset Your Android Phone or Tablet When It Won’t Boot Our Geek Trivia App for Windows 8 is Now Available Everywhere

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• Inside the Raspberry Pi Factory

  - by Jason Fitzpatrick

  Curious where your pint-sized Raspberry Pi came from? You might be surprised to learn it was built, tested, and packaged all in an equally pint-sized factory in South Wales. Nick Heath of Tech Republic takes us on a photo tour of the Raspberry Pi factory with a stop at each stage of production and testing. The photo above shows one of the manual construction steps, the insertion of the large components such as the USB and Ethernet ports. Hit up the link below for the full tour. Raspberry Pi: Inside the Pi Factory [Tech Republic] Our Geek Trivia App for Windows 8 is Now Available Everywhere How To Boot Your Android Phone or Tablet Into Safe Mode HTG Explains: Does Your Android Phone Need an Antivirus?

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• Integrating NetBeans for Raspberry Pi Java Development

  - by speakjava

  Raspberry Pi IDE Java Development The Raspberry Pi is an incredible device for building embedded Java applications but, despite being able to run an IDE on the Pi it really pushes things to the limit.  It's much better to use a PC or laptop to develop the code and then deploy and test on the Pi.  What I thought I'd do in this blog entry was to run through the steps necessary to set up NetBeans on a PC for Java code development, with automatic deployment to the Raspberry Pi as part of the build process. I will assume that your starting point is a Raspberry Pi with an SD card that has one of the latest Raspbian images on it.  This is good because this now includes the JDK 7 as part of the distro, so no need to download and install a separate JDK.  I will also assume that you have installed the JDK and NetBeans on your PC.  These can be downloaded here. There are numerous approaches you can take to this including mounting the file system from the Raspberry Pi remotely on your development machine.  I tried this and I found that NetBeans got rather upset if the file system disappeared either through network interruption or the Raspberry Pi being turned off.  The following method uses copying over SSH, which will fail more gracefully if the Pi is not responding. Step 1: Enable SSH on the Raspberry Pi To run the Java applications you create you will need to start Java on the Raspberry Pi with the appropriate class name, classpath and parameters.  For non-JavaFX applications you can either do this from the Raspberry Pi desktop or, if you do not have a monitor connected through a remote command line.  To execute the remote command line you need to enable SSH (a secure shell login over the network) and connect using an application like PuTTY. You can enable SSH when you first boot the Raspberry Pi, as the raspi-config program runs automatically.  You can also run it at any time afterwards by running the command: sudo raspi-config This will bring up a menu of options.  Select '8 Advanced Options' and on the next screen select 'A$ SSH'.  Select 'Enable' and the task is complete. Step 2: Configure Raspberry Pi Networking By default, the Raspbian distribution configures the ethernet connection to use DHCP rather than a static IP address.  You can continue to use DHCP if you want, but to avoid having to potentially change settings whenever you reboot the Pi using a static IP address is simpler. To configure this on the Pi you need to edit the /etc/network/interfaces file.  You will need to do this as root using the sudo command, so something like sudo vi /etc/network/interfaces.  In this file you will see this line: iface eth0 inet dhcp This needs to be changed to the following: iface eth0 inet static     address 10.0.0.2     gateway 10.0.0.254     netmask 255.255.255.0 You will need to change the values in red to an appropriate IP address and to match the address of your gateway. Step 3: Create a Public-Private Key Pair On Your Development Machine How you do this will depend on which Operating system you are using: Mac OSX or Linux Run the command: ssh-keygen -t rsa Press ENTER/RETURN to accept the default destination for saving the key.  We do not need a passphrase so simply press ENTER/RETURN for an empty one and once more to confirm. The key will be created in the file .ssh/id_rsa.pub in your home directory.  Display the contents of this file using the cat command: cat ~/.ssh/id_rsa.pub Open a window, SSH to the Raspberry Pi and login.  Change directory to .ssh and edit the authorized_keys file (don't worry if the file does not exist).  Copy and paste the contents of the id_rsa.pub file to the authorized_keys file and save it. Windows Since Windows is not a UNIX derivative operating system it does not include the necessary key generating software by default.  To generate the key I used puttygen.exe which is available from the same site that provides the PuTTY application, here. Download this and run it on your Windows machine.  Follow the instructions to generate a key.  I remove the key comment, but you can leave that if you want. Click "Save private key", confirm that you don't want to use a passphrase and select a filename and location for the key. Copy the public key from the part of the window marked, "Public key for pasting into OpenSSH authorized_keys file".  Use PuTTY to connect to the Raspberry Pi and login.  Change directory to .ssh and edit the authorized_keys file (don't worry if this does not exist).  Paste the key information at the end of this file and save it. Logout and then start PuTTY again.  This time we need to create a saved session using the private key.  Type in the IP address of the Raspberry Pi in the "Hostname (or IP address)" field and expand "SSH" under the "Connection" category.  Select "Auth" (see the screen shot below). Click the "Browse" button under "Private key file for authentication" and select the file you saved from puttygen. Go back to the "Session" category and enter a short name in the saved sessions field, as shown below.  Click "Save" to save the session. Step 4: Test The Configuration You should now have the ability to use scp (Mac/Linux) or pscp.exe (Windows) to copy files from your development machine to the Raspberry Pi without needing to authenticate by typing in a password (so we can automate the process in NetBeans).  It's a good idea to test this using something like: scp /tmp/foo [email protected]:/tmp on Linux or Mac or pscp.exe foo pi@raspi:/tmp on Windows (Note that we use the saved configuration name instead of the IP address or hostname so the public key is picked up). pscp.exe is another tool available from the creators of PuTTY. Step 5: Configure the NetBeans Build Script Start NetBeans and create a new project (or open an existing one that you want to deploy automatically to the Raspberry Pi). Select the Files tab in the explorer window and expand your project.  You will see a build.xml file.  Double click this to edit it. This file will mostly be comments.  At the end (but within the </project> tag) add the XML for <target name="-post-jar">, shown below Here's the code again in case you want to use cut-and-paste: <target name="-post-jar">   <echo level="info" message="Copying dist directory to remote Pi"/>   <exec executable="scp" dir="${basedir}">     <arg line="-r"/>     <arg value="dist"/>     <arg value="[email protected]:NetBeans/CopyTest"/>   </exec>  </target> For Windows it will be slightly different: <target name="-post-jar">   <echo level="info" message="Copying dist directory to remote Pi"/>   <exec executable="C:\pi\putty\pscp.exe" dir="${basedir}">     <arg line="-r"/>     <arg value="dist"/>     <arg value="pi@raspi:NetBeans/CopyTest"/>   </exec> </target> You will also need to ensure that pscp.exe is in your PATH (or specify a fully qualified pathname). From now on when you clean and build the project the dist directory will automatically be copied to the Raspberry Pi ready for testing.

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• Simple monitoring of a Raspberry Pi powered screen - Part 2

  - by Chris Houston

  If you have read my previous blog post Raspberry Pi entrance signed backed by Umbraco - Part 1 which describes how we used a Raspberry Pi to drive an Entrance sign for QV Offices you will have seen I mentioned a follow up post about monitoring the sign.As the sign is mounted in the entrance of the building on the ground floor and the reception is on the 1st floor, this meant that if there was a fault of any kind showing on the screen, the first person to see this was inevitably one of QV Offices' clients as they walked into the building.Although the QV Offices' team were able to check the Umbraco website address that the sign uses, this did not always mean that everything was working as expected. We noticed a couple of times that the sign had Wifi issues (it is now hard wired) and this caused the Chromium browser to render a 404 error when it tried to refresh the screen.The simple monitoring solutionWe added the following line to our refresh script, so that after the sign had been refreshed a screen shot of the Raspberry Pi would be taken:import -display :0 -window root ~/screenshot.jpgFinally we wrote a small Crontab task that ran on a QV Offices Mac that grabs this screen shot and saved it on the desktop, admittedly we have used a package that it not mega secure, but in reality this is an internal system that only runs an office sign, so we are not to concerned about it being hacked.*/5 * * * * /usr/local/bin/sshpass -p 'password' /usr/bin/scp [email protected]:screenshot.jpg Desktop/QVScreenShot.jpgAs the file icon updates, if the image changes, this gives a quick visual indication of the status of the sign, if for some reason the icon does not look correct the QV Offices administrator can just click on the file to see the exact image currently displayed on the sign.Sometimes a quick and easy solution is better than a more complex and expensive one.

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• Raspberry Pi Powered Coffee Table Serves Up Arcade Classics

  - by Jason Fitzpatrick

  If your living room is boring for want of a plethora of arcade hits, this DIY project parks a Raspberry Pi powered arcade machine in a coffee table for at-your-finger-tips retro gaming. Courtesy of tinker Graham Gelding, this build combines a 24-inch monitor, arcade buttons, a Raspberry Pi board, and a wooden coffee table to great effect. The end result is a table-top style arcade that also doubles, courtesy of a wireless keyboard and mouse, as a web browsing and email station. Hit up the link below for more information. Coffee Table Pi [via Hack A Day] HTG Explains: Why It’s Good That Your Computer’s RAM Is Full 10 Awesome Improvements For Desktop Users in Windows 8 How To Play DVDs on Windows 8

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• Get Hands On with Raspberry Pi via Free OS-Building Course

  - by Jason Fitzpatrick

  Cambridge University is now offering a free 12-segment course that will guide you through building an OS from scratch for the tiny Raspberry Pi development board–learn the ins and outs of basic OS design on the cheap. You’ll need a Raspberry Pi board, a computer running Windows, OS X, or Linux, and an SD card, as well as a small amount of free software. The 12-part tutorial starts you off with basic OS theory and then walks you through basic control of the board, graphics manipulation, and, finally, creating a command line interface for your new operating system. Hit up the link below to read more and check out the lessons. Baking Pi – Operating Systems Development HTG Explains: What The Windows Event Viewer Is and How You Can Use It HTG Explains: How Windows Uses The Task Scheduler for System Tasks HTG Explains: Why Do Hard Drives Show the Wrong Capacity in Windows?

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• New on the Java Channel: Low-Latency Applications, JavaFX on Raspberry PI, and more

  - by terrencebarr

  If you haven’t checked out the Java YouTube channel lately … here is some of the stuff you’re missing: Understanding the JVM and Low Latency Applications (picture) JavaFX on the Raspberry Pi 55 New Java 7 Features: Part 3 – Concurrency Properties and Binding with JavaFX 2 Intro And something fun & cool: Java @ Maker Faire 2012 Much more on the Java Channel. Enjoy! Cheers, – Terrence Filed under: Mobile & Embedded Tagged: Embedded Java, Java 7, Java Channel, Java Embedded, JavaFX, Maker Faire, Raspberry Pi, video, webcast, YouTube

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• Raspberry Pi Micro Arcade Machine Packs Gaming into a Tiny Case

  - by Jason Fitzpatrick

  While it might be more practical to build a full-size MAME cabinet for your retro gaming enjoyment, this tiny and fully functional build is a great example of the fun you can have tinkering with electronics. Read on to see a video of it in action. Courtesy of tinker and electronics hobbyist Sprite over at SpriteMods, the build is clever in so many ways. The heart of the device is a Raspberry Pi board, it includes a tiny video marque that displays the logo of whatever game you’re playing, and the micro-scaled joystick and buttons are fully functional. Hit up the link below for his detailed build guide including his custom built cellphone-battery based charging system. Raspberry Pi Micro Arcade Machine [via Hack A Day] How To Use USB Drives With the Nexus 7 and Other Android Devices Why Does 64-Bit Windows Need a Separate “Program Files (x86)” Folder? Why Your Android Phone Isn’t Getting Operating System Updates and What You Can Do About It

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• Prepping the Raspberry Pi for Java Excellence (part 1)

  - by HecklerMark

  I've only recently been able to begin working seriously with my first Raspberry Pi, received months ago but hastily shelved in preparation for JavaOne. The Raspberry Pi and other diminutive computing platforms offer a glimpse of the potential of what is often referred to as the embedded space, the "Internet of Things" (IoT), or Machine to Machine (M2M) computing. I have a few different configurations I want to use for multiple Raspberry Pis, but for each of them, I'll need to perform the following common steps to prepare them for their various tasks: Load an OS onto an SD card Get the Pi connected to the network Load a JDK I've been very happy to see good friend and JFXtras teammate Gerrit Grunwald document how to do these things on his blog (link to article here - check it out!), but I ran into some issues configuring wi-fi that caused me some needless grief. Not knowing if any of the pitfalls were caused by my slightly-older version of the Pi and not being able to find anything specific online to help me get past it, I kept chipping away at it until I broke through. The purpose of this post is to (hopefully) help someone else recognize the same issues if/when they encounter them and work past them quickly. There is a great resource page here that covers several ways to get the OS on an SD card, but here is what I did (on a Mac): Plug SD card into reader on/in Mac Format it (FAT32) Unmount it (diskutil unmountDisk diskn, where n is the disk number representing the SD card) Transfer the disk image for Debian to the SD card (dd if=2012-08-08-wheezy-armel.img of=/dev/diskn bs=1m) Eject the card from the Mac (diskutil eject diskn) There are other ways, but this is fairly quick and painless, especially after you do it several times. Yes, I had to do that dance repeatedly (minus formatting) due to the wi-fi issues, as it kept killing the ability of the Pi to boot. You should be able to dramatically reduce the number of OS loads you do, though, if you do a few things with regard to your wi-fi. Firstly, I strongly recommend you purchase the Edimax EW-7811Un wi-fi adapter. This adapter/chipset has been proven with the Raspberry Pi, it's tiny, and it's cheap. Avoid unnecessary aggravation and buy this one! Secondly, visit this page for a script and instructions regarding how to configure your new wi-fi adapter with your Pi. Here is the rub, though: there is a missing step. At least for my combination of Pi version, OS version, and uncanny gift of timing and luck there was. :-) Here is the sequence of steps I used to make the magic happen: Plug your newly-minted SD card (with OS) into your Pi and connect a network cable (for internet connectivity) Boot your Pi. On the first boot, do the following things: Opt to have it use all space on the SD card (will require a reboot eventually) Disable overscan Set your timezone Enable the ssh server Update raspi-config Reboot your Pi. This will reconfigure the SD to use all space (see above). After you log in (UID: pi, password: raspberry), upgrade your OS. This was the missing step for me that put a merciful end to the repeated SD card re-imaging and made the wi-fi configuration trivial. To do so, just type sudo apt-get upgrade and give it several minutes to complete. Pour yourself a cup of coffee and congratulate yourself on the time you've just saved.  ;-) With the OS upgrade finished, now you can follow Mr. Engman's directions (to the letter, please see link above), download his script, and let it work its magic. One aside: I plugged the little power-sipping Edimax directly into the Pi and it worked perfectly. No powered hub needed, at least in my configuration. To recap, that OS upgrade (at least at this point, with this combination of OS/drivers/Pi version) is absolutely essential for a smooth experience. Miss that step, and you're in for hours of "fun". Save yourself! I'll pick up next time with more of the Java side of the RasPi configuration, but as they say, you have to cross the moat to get into the castle. Hopefully, this will help you do just that. Until next time! All the best, Mark 

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• Pi help............ [closed]

  - by Pieman

  Help update Pi: http://zombiewrath.com/pi.php :)

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• Raspberry pi slows down my entire network

  - by gnusouth

  Whenever my Raspberry Pi is connected to the network (via ethernet) the entire network is slowed to a crawl. On my main computer, ping times for google.com go from ~10ms to ~200ms and it takes forever to load web pages. Connections are also slow on the Pi, with an apt-get update showing pathetic speeds in the order of 1KB/s. Turning off the Pi completely removes the drag from the network. I've tried static and dynamic IP addresses for the Pi, but both have the same problems. I'm currently using Raspbian (downloaded today), but also had this problem with Arch Linux. I've checked the connection's duplex with dmesg | grep -i duplex, which shows that the Pi's connection is running at 100Mbps, full-duplex, as expected. My modem/router is a Billion 7404VNPX (an Australian thing); relatively high-end, albeit a bit buggy at times (it will occassionally delete all its firewall settings). It assigns IPs in the range 192.168.1.1 to 192.168.1.20 and has 192.168.1.254 as its own IP. When I assign static IPs I tend to use the 192.168.1.200 area. Does anyone have any idea as to what could be causing this weird slowdown? Or any tests I could try? Thanks

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• how to make a function recursive

  - by tom smith

  i have this huge function and i am wondering how to make it recursive. i have the base case which should never come true, so it should always go to else and keep calling itself with the variable t increases. any help would be great thanks def draw(x, y, t, planets): if 'Satellites' in planets["Moon"]: print ("fillcircle", x, y, planets["Moon"]['Radius']*scale) else: while True: print("refresh") print("colour 0 0 0") print("clear") print("colour 255 255 255") print("fillcircle",x,y,planets['Sun']['Radius']*scale) print("text ", "\"Sun\"",x+planets['Sun']['Radius']*scale,y) if "Mercury" in planets: r_Mercury=planets['Mercury']['Orbital Radius']*scale; print("circle",x,y,r_Mercury) r_Xmer=x+math.sin(t*2*math.pi/planets['Mercury']['Period'])*r_Mercury r_Ymer=y+math.cos(t*2*math.pi/planets['Mercury']['Period'])*r_Mercury print("fillcircle",r_Xmer,r_Ymer,3) print("text ", "\"Mercury\"",r_Xmer+planets['Mercury']['Radius']*scale,r_Ymer) if "Venus" in planets: r_Venus=planets['Venus']['Orbital Radius']*scale; print("circle",x,y,r_Venus) r_Xven=x+math.sin(t*2*math.pi/planets['Venus']['Period'])*r_Venus r_Yven=y+math.cos(t*2*math.pi/planets['Venus']['Period'])*r_Venus print("fillcircle",r_Xven,r_Yven,3) print("text ", "\"Venus\"",r_Xven+planets['Venus']['Radius']*scale,r_Yven) if "Earth" in planets: r_Earth=planets['Earth']['Orbital Radius']*scale; print("circle",x,y,r_Earth) r_Xe=x+math.sin(t*2*math.pi/planets['Earth']['Period'])*r_Earth r_Ye=y+math.cos(t*2*math.pi/planets['Earth']['Period'])*r_Earth print("fillcircle",r_Xe,r_Ye,3) print("text ", "\"Earth\"",r_Xe+planets['Earth']['Radius']*scale,r_Ye) if "Moon" in planets: r_Moon=planets['Moon']['Orbital Radius']*scale; print("circle",r_Xe,r_Ye,r_Moon) r_Xm=r_Xe+math.sin(t*2*math.pi/planets['Moon']['Period'])*r_Moon r_Ym=r_Ye+math.cos(t*2*math.pi/planets['Moon']['Period'])*r_Moon print("fillcircle",r_Xm,r_Ym,3) print("text ", "\"Moon\"",r_Xm+planets['Moon']['Radius']*scale,r_Ym) if "Mars" in planets: r_Mars=planets['Mars']['Orbital Radius']*scale; print("circle",x,y,r_Mars) r_Xmar=x+math.sin(t*2*math.pi/planets['Mars']['Period'])*r_Mars r_Ymar=y+math.cos(t*2*math.pi/planets['Mars']['Period'])*r_Mars print("fillcircle",r_Xmar,r_Ymar,3) print("text ", "\"Mars\"",r_Xmar+planets['Mars']['Radius']*scale,r_Ymar) if "Phobos" in planets: r_Phobos=planets['Phobos']['Orbital Radius']*scale; print("circle",r_Xmar,r_Ymar,r_Phobos) r_Xpho=r_Xmar+math.sin(t*2*math.pi/planets['Phobos']['Period'])*r_Phobos r_Ypho=r_Ymar+math.cos(t*2*math.pi/planets['Phobos']['Period'])*r_Phobos print("fillcircle",r_Xpho,r_Ypho,3) print("text ", "\"Phobos\"",r_Xpho+planets['Phobos']['Radius']*scale,r_Ypho) if "Deimos" in planets: r_Deimos=planets['Deimos']['Orbital Radius']*scale; print("circle",r_Xmar,r_Ymar,r_Deimos) r_Xdei=r_Xmar+math.sin(t*2*math.pi/planets['Deimos']['Period'])*r_Deimos r_Ydei=r_Ymar+math.cos(t*2*math.pi/planets['Deimos']['Period'])*r_Deimos print("fillcircle",r_Xdei,r_Ydei,3) print("text ", "\"Deimos\"",r_Xpho+planets['Deimos']['Radius']*scale,r_Ydei) if "Ceres" in planets: r_Ceres=planets['Ceres']['Orbital Radius']*scale; print("circle",x,y,r_Ceres) r_Xcer=x+math.sin(t*2*math.pi/planets['Ceres']['Period'])*r_Ceres r_Ycer=y+math.cos(t*2*math.pi/planets['Ceres']['Period'])*r_Ceres print("fillcircle",r_Xcer,r_Ycer,3) print("text ", "\"Ceres\"",r_Xcer+planets['Ceres']['Radius']*scale,r_Ycer) if "Jupiter" in planets: r_Jupiter=planets['Jupiter']['Orbital Radius']*scale; print("circle",x,y,r_Jupiter) r_Xjup=x+math.sin(t*2*math.pi/planets['Jupiter']['Period'])*r_Jupiter r_Yjup=y+math.cos(t*2*math.pi/planets['Jupiter']['Period'])*r_Jupiter print("fillcircle",r_Xjup,r_Yjup,3) print("text ", "\"Jupiter\"",r_Xjup+planets['Jupiter']['Radius']*scale,r_Yjup) if "Io" in planets: r_Io=planets['Io']['Orbital Radius']*scale; print("circle",r_Xjup,r_Yjup,r_Io) r_Xio=r_Xjup+math.sin(t*2*math.pi/planets['Io']['Period'])*r_Io r_Yio=r_Yjup+math.cos(t*2*math.pi/planets['Io']['Period'])*r_Io print("fillcircle",r_Xio,r_Yio,3) print("text ", "\"Io\"",r_Xio+planets['Io']['Radius']*scale,r_Yio) if "Europa" in planets: r_Europa=planets['Europa']['Orbital Radius']*scale; print("circle",r_Xjup,r_Yjup,r_Europa) r_Xeur=r_Xjup+math.sin(t*2*math.pi/planets['Europa']['Period'])*r_Europa r_Yeur=r_Yjup+math.cos(t*2*math.pi/planets['Europa']['Period'])*r_Europa print("fillcircle",r_Xeur,r_Yeur,3) print("text ", "\"Europa\"",r_Xeur+planets['Europa']['Radius']*scale,r_Yeur) if "Ganymede" in planets: r_Ganymede=planets['Ganymede']['Orbital Radius']*scale; print("circle",r_Xjup,r_Yjup,r_Ganymede) r_Xgan=r_Xjup+math.sin(t*2*math.pi/planets['Ganymede']['Period'])*r_Ganymede r_Ygan=r_Yjup+math.cos(t*2*math.pi/planets['Ganymede']['Period'])*r_Ganymede print("fillcircle",r_Xgan,r_Ygan,3) print("text ", "\"Ganymede\"",r_Xgan+planets['Ganymede']['Radius']*scale,r_Ygan) if "Callisto" in planets: r_Callisto=planets['Callisto']['Orbital Radius']*scale; print("circle",r_Xjup,r_Yjup,r_Callisto) r_Xcal=r_Xjup+math.sin(t*2*math.pi/planets['Callisto']['Period'])*r_Callisto r_Ycal=r_Yjup+math.cos(t*2*math.pi/planets['Callisto']['Period'])*r_Callisto print("fillcircle",r_Xcal,r_Ycal,3) print("text ", "\"Callisto\"",r_Xcal+planets['Callisto']['Radius']*scale,r_Ycal) if "Saturn" in planets: r_Saturn=planets['Saturn']['Orbital Radius']*scale; print("circle",x,y,r_Saturn) r_Xsat=x+math.sin(t*2*math.pi/planets['Saturn']['Period'])*r_Saturn r_Ysat=y+math.cos(t*2*math.pi/planets['Saturn']['Period'])*r_Saturn print("fillcircle",r_Xsat,r_Ysat,3) print("text ", "\"Saturn\"",r_Xsat+planets['Saturn']['Radius']*scale,r_Ysat) if "Mimas" in planets: r_Mimas=planets['Mimas']['Orbital Radius']*scale; print("circle",r_Xsat,r_Ysat,r_Mimas) r_Xmim=r_Xsat+math.sin(t*2*math.pi/planets['Mimas']['Period'])*r_Mimas r_Ymim=r_Ysat+math.cos(t*2*math.pi/planets['Mimas']['Period'])*r_Mimas print("fillcircle",r_Xmim,r_Ymim,3) print("text ", "\"Mimas\"",r_Xmim+planets['Mimas']['Radius']*scale,r_Ymim) if "Enceladus" in planets: r_Enceladus=planets['Enceladus']['Orbital Radius']*scale; print("circle",r_Xsat,r_Ysat,r_Enceladus) r_Xenc=r_Xsat+math.sin(t*2*math.pi/planets['Enceladus']['Period'])*r_Enceladus r_Yenc=r_Ysat+math.cos(t*2*math.pi/planets['Enceladus']['Period'])*r_Enceladus print("fillcircle",r_Xenc,r_Yenc,3) print("text ", "\"Enceladus\"",r_Xenc+planets['Enceladus']['Radius']*scale,r_Yenc) if "Tethys" in planets: r_Tethys=planets['Tethys']['Orbital Radius']*scale; print("circle",r_Xsat,r_Ysat,r_Tethys) r_Xtet=r_Xsat+math.sin(t*2*math.pi/planets['Tethys']['Period'])*r_Tethys r_Ytet=r_Ysat+math.cos(t*2*math.pi/planets['Tethys']['Period'])*r_Tethys print("fillcircle",r_Xtet,r_Ytet,3) print("text ", "\"Tethys\"",r_Xtet+planets['Tethys']['Radius']*scale,r_Ytet) if "Dione" in planets: r_Dione=planets['Dione']['Orbital Radius']*scale; print("circle",r_Xsat,r_Ysat,r_Dione) r_Xdio=r_Xsat+math.sin(t*2*math.pi/planets['Dione']['Period'])*r_Dione r_Ydio=r_Ysat+math.cos(t*2*math.pi/planets['Dione']['Period'])*r_Dione print("fillcircle",r_Xdio,r_Ydio,3) print("text ", "\"Dione\"",r_Xdio+planets['Dione']['Radius']*scale,r_Ydio) if "Rhea" in planets: r_Rhea=planets['Rhea']['Orbital Radius']*scale; print("circle",r_Xsat,r_Ysat,r_Rhea) r_Xrhe=r_Xsat+math.sin(t*2*math.pi/planets['Rhea']['Period'])*r_Rhea r_Yrhe=r_Ysat+math.cos(t*2*math.pi/planets['Rhea']['Period'])*r_Rhea print("fillcircle",r_Xrhe,r_Yrhe,3) print("text ", "\"Rhea\"",r_Xrhe+planets['Rhea']['Radius']*scale,r_Yrhe) if "Titan" in planets: r_Titan=planets['Titan']['Orbital Radius']*scale; print("circle",r_Xsat,r_Ysat,r_Titan) r_Xtit=r_Xsat+math.sin(t*2*math.pi/planets['Titan']['Period'])*r_Titan r_Ytit=r_Ysat+math.cos(t*2*math.pi/planets['Titan']['Period'])*r_Titan print("fillcircle",r_Xtit,r_Ytit,3) print("text ", "\"Titan\"",r_Xtit+planets['Titan']['Radius']*scale,r_Ytit) if "Iapetus" in planets: r_Iapetus=planets['Iapetus']['Orbital Radius']*scale; print("circle",r_Xsat,r_Ysat,r_Iapetus) r_Xiap=r_Xsat+math.sin(t*2*math.pi/planets['Iapetus']['Period'])*r_Iapetus r_Yiap=r_Ysat+math.cos(t*2*math.pi/planets['Iapetus']['Period'])*r_Iapetus print("fillcircle",r_Xiap,r_Yiap,3) print("text ", "\"Iapetus\"",r_Xiap+planets['Iapetus']['Radius']*scale,r_Yiap) if "Uranus" in planets: r_Uranus=planets['Uranus']['Orbital Radius']*scale; print("circle",x,y,r_Uranus) r_Xura=x+math.sin(t*2*math.pi/planets['Uranus']['Period'])*r_Uranus r_Yura=y+math.cos(t*2*math.pi/planets['Uranus']['Period'])*r_Uranus print("fillcircle",r_Xura,r_Yura,3) print("text ", "\"Uranus\"",r_Xura+planets['Uranus']['Radius']*scale,r_Yura) if "Puck" in planets: r_Puck=planets['Puck']['Orbital Radius']*scale; print("circle",r_Xura,r_Yura,r_Puck) r_Xpuc=r_Xura+math.sin(t*2*math.pi/planets['Puck']['Period'])*r_Puck r_Ypuc=r_Yura+math.cos(t*2*math.pi/planets['Puck']['Period'])*r_Puck print("fillcircle",r_Xpuc,r_Ypuc,3) print("text ", "\"Puck\"",r_Xpuc+planets['Puck']['Radius']*scale,r_Ypuc) if "Miranda" in planets: r_Miranda=planets['Miranda']['Orbital Radius']*scale; print("circle",r_Xura,r_Yura,r_Miranda) r_Xmira=r_Xura+math.sin(t*2*math.pi/planets['Miranda']['Period'])*r_Miranda r_Ymira=r_Yura+math.cos(t*2*math.pi/planets['Miranda']['Period'])*r_Miranda print("fillcircle",r_Xmira,r_Ymira,3) print("text ", "\"Miranda\"",r_Xmira+planets['Miranda']['Radius']*scale,r_Ymira) if "Ariel" in planets: r_Ariel=planets['Ariel']['Orbital Radius']*scale; print("circle",r_Xura,r_Yura,r_Ariel) r_Xari=r_Xura+math.sin(t*2*math.pi/planets['Ariel']['Period'])*r_Ariel r_Yari=r_Yura+math.cos(t*2*math.pi/planets['Ariel']['Period'])*r_Ariel print("fillcircle",r_Xari,r_Yari,3) print("text ", "\"Ariel\"",r_Xari+planets['Ariel']['Radius']*scale,r_Yari) if "Umbriel" in planets: r_Umbriel=planets['Umbriel']['Orbital Radius']*scale; print("circle",r_Xura,r_Yura,r_Umbriel) r_Xumb=r_Xura+math.sin(t*2*math.pi/planets['Umbriel']['Period'])*r_Umbriel r_Yumb=r_Yura+math.cos(t*2*math.pi/planets['Umbriel']['Period'])*r_Umbriel print("fillcircle",r_Xumb,r_Yumb,3) print("text ", "\"Umbriel\"",r_Xumb+planets['Umbriel']['Radius']*scale,r_Yumb) if "Titania" in planets: r_Titania=planets['Titania']['Orbital Radius']*scale; print("circle",r_Xura,r_Yura,r_Titania) r_Xtita=r_Xura+math.sin(t*2*math.pi/planets['Titania']['Period'])*r_Titania r_Ytita=r_Yura+math.cos(t*2*math.pi/planets['Titania']['Period'])*r_Titania print("fillcircle",r_Xtita,r_Ytita,3) print("text ", "\"Titania\"",r_Xtita+planets['Titania']['Radius']*scale,r_Ytita) if "Oberon" in planets: r_Oberon=planets['Oberon']['Orbital Radius']*scale; print("circle",r_Xura,r_Yura,r_Oberon) r_Xober=r_Xura+math.sin(t*2*math.pi/planets['Oberon']['Period'])*r_Oberon r_Yober=r_Yura+math.cos(t*2*math.pi/planets['Oberon']['Period'])*r_Oberon print("fillcircle",r_Xober,r_Yober,3) print("text ", "\"Oberon\"",r_Xober+planets['Oberon']['Radius']*scale,r_Yober) if "Neptune" in planets: r_Neptune=planets['Neptune']['Orbital Radius']*scale; print("circle",x,y,r_Neptune) r_Xnep=x+math.sin(t*2*math.pi/planets['Neptune']['Period'])*r_Neptune r_Ynep=y+math.cos(t*2*math.pi/planets['Neptune']['Period'])*r_Neptune print("fillcircle",r_Xnep,r_Ynep,3) print("text ", "\"Neptune\"",r_Xnep+planets['Neptune']['Radius']*scale,r_Ynep) if "Titan" in planets: r_Titan=planets['Titan']['Orbital Radius']*scale; print("circle",r_Xnep,r_Ynep,r_Titan) r_Xtita=r_Xnep+math.sin(t*2*math.pi/planets['Titan']['Period'])*r_Titan r_Ytita=r_Ynep+math.cos(t*2*math.pi/planets['Titan']['Period'])*r_Titan print("fillcircle",r_Xtita,r_Ytita,3) print("text ", "\"Titan\"",r_Xtita+planets['Titan']['Radius']*scale,r_Ytita) t += 0.003 print(draw(x, y, t, planets))

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• Linux Cups raspberry pi offload processing to server

  - by jaredmsaul

  I am interested in setting up a raspberry pi as the local end of a printing solution. In my testing the pi chokes on acting as a complete cups based print server. It seems a little underpowered for some of the ghostscipt processing and other filtering that occurs-- particularly on larger or complex documents the processing time can be 5 or more minutes. My question is can the processing be largely done elsewhere and the prepared end product of the processing chain be fed to the pi for output on the connected printer? So in this scenario any arbitrary document (html, pdf, text) is initially 'printed' on a relatively powerful machine but the output is stored in a file. This file is then grabbed by the pi and with all the heavy work out of the way easily printed using cups. I know files can be pushed through cups in raw mode but I am fuzzy on the pros and cons and the applicability in what I describe. I have tested this with pdftops creating a ps file then feeding that raw to cups and I think it works but it seems like there may be a cleaner solution. This scenario would ideally work for any number of printer types.

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• Connect devices plugged into Raspberry Pi ethernet to WiFi network

  - by Tom

  I'm just starting out on a mission to learn more about networking and I've followed a tutorial (http://raspberrypihq.com/how-to-turn-a-raspberry-pi-into-a-wifi-router/) to turn my Raspberry Pi into a wifi router. That worked really well so I modified it slightly so that I can use a tethered iphone for the internet connection - I just switched all "eth0" references to "eth1" (the iphone interface) and added a script to set everything up when the phone is plugged in. This setup has freed up the Pi's ethernet port so I'd like to try and take this a step further and allow devices plugged into it to connect to the network. If possible, I'd like to try adding a switch so I can connect multiple devices. I've tried fiddling around with nat & iptables with no luck so my question is, how can I connect devices on eth0 to my wlan network?

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• raspberry pi for web programming/development

  - by Mark Dee

  I'm into web development and my machine (AMD Phenom II, 8G RAM) is running Ubuntu 13.04. I love my current setup but I kinda miss some of Windows software like MSOffice or Adobe suites, and running on Virtualbox doesn't feel as snappy for me.... So I'm thinking of buying a new cheap machine where I would install Linux and do my development work there and have my current machine run Windows. I just found this thing called Raspberry pi which is really cheap and requires 12v only (I think) which makes it good for downloading stuff overnight. So, does it make sense to buy Raspberry pi, make it my primary dev machine, Windows being the secondary (for Adobe and browser testing of course)? Basically, I want to know if Raspberry pi meets the following requirements: It should run ArchLinux Sublime Text 3 python ruby nginx nodejs Deluge or Transmission (well, maybe just those, no need for videos and music players)

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• Raspberry Pi and Java SE: A Platform for the Masses

  - by Jim Connors

  One of the more exciting developments in the embedded systems world has been the announcement and availability of the Raspberry Pi, a very capable computer that is no bigger than a credit card.  At $35 US, initial demand for the device was so significant, that very long back orders quickly ensued. After months of patiently waiting, mine finally arrived.  Those initial growing pains appear to have been fixed, so availability now should be much more reasonable. At a very high level, here are some of the important specs: Broadcom BCM2835 System on a chip (SoC) ARM1176JZFS, with floating point, running at 700MHz Videocore 4 GPU capable of BluRay quality playback 256Mb RAM 2 USB ports and Ethernet Boots from SD card Linux distributions (e.g. Debian) available So what's taking place taking place with respect to the Java platform and Raspberry Pi? A Java SE Embedded binary suitable for the Raspberry Pi is available for download (Arm v6/7) here.  Note, this is based on the armel architecture, a variety of Arm designed to support floating point through a compatibility library that operates on more platforms, but can hamper performance.  In order to use this Java SE binary, select the available Debian distribution for your Raspberry Pi. The more recent Raspbian distribution is based on the armhf (hard float) architecture, which provides for more efficient hardware-based floating point operations.  However armhf is not binary compatible with armel.  As of the writing of this blog, Java SE Embedded binaries are not yet publicly available for the armhf-based Raspbian distro, but as mentioned in Henrik Stahl's blog, an armhf release is in the works. As demonstrated at the just-completed JavaOne 2012 San Francisco event, the graphics processing unit inside the Raspberry Pi is very capable indeed, and makes for an excellent candidate for JavaFX.  As such, plans also call for a Pi-optimized version of JavaFX in a future release too. A thriving community around the Raspberry Pi has developed at light speed, and as evidenced by the packed attendance at Pi-specific sessions at Java One 2012, the interest in Java for this platform is following suit. So stay tuned for more developments...

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• Sending text messages from Raspberry Pi via email fails

  - by vgm64

  I'm using mailx on my raspberry pi to try to send text messages updates for event monitoring. My phone number: 9876543210 My phone's email-to-text gateway address: [email protected] I can 1) Send emails from my raspberry pi to various email addresses. mail -r [email protected] -s "My Subject" [email protected] < body.txt and off it goes and is successfully delivered. 2) Send emails from various email address (not on RPi) using mailx to the above phone-email address and have them delivered as text messages. However, when sending emails to [email protected] from the Raspberry Pi using mailx the emails seem to spiral into the void and are never heard of again (no errors, no undeliverable messages, nothing). Does anyone know what could be causing this to go awry? Something about the basic deployment of the mail server on the pi? EDIT Based on @kobaltz's suggestion, I used sendmail instead. This led to a hang, then an error that stated that I lacked a fully qualified domain name (FQDN). I then used this website's instructions to add a domain name to the RPi. To paraphrase: I have set the FQDN in /etc/hostname: my-host-name.my-domain.com and /etc/hosts: 127.0.0.1 localhost.localdomain localhost 192.168.0.5 my-host-name.my-domain.com my-host-name Then add to /etc/mail/sendmail.cf: MASQUERADE_AS(`my-domain.com') MASQUERADE_DOMAIN(`my-host-name.my-domain.com') FEATURE(`masquerade_entire_domain') FEATURE(`masquerade_envelope') I put this in /etc/mail/sendmail.cf, BEFORE the MAILER() lines, ran sendmailconfig, answered Yes to the questions about using the existing files, and restarted sendmail. Emails now have the proper domain name. Progress, however, I am now stuck at the following error: 354 Enter mail, end with "." on a line by itself >>> . 050 <[email protected]>... Connecting to mxx.cingularme.com. via esmtp... 050 421 Service not available 050 >>> QUIT 050 <[email protected]>... Deferred: 421 Service not available 250 2.0.0 q9U3ZESt021150 Message accepted for delivery [email protected]... Sent (q9U3ZESt021150 Message accepted for delivery) Closing connection to [127.0.0.1] >>> QUIT

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• Raspberry Pi can't see external hard drive

  - by user265818

  My Raspberry Pi (Model B) can't see my external hard drive. It was working before without a problem, until I disconnected and reconnected the drive. It is a self-powered hard drive. When I put another image on a different SD card the Raspberry Pi can see the hard drive no problem, so there is some sort of configuration issue in the current image on the SD card. Any advice will be gratefully received.

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• Session Report - Java on the Raspberry Pi

  - by Janice J. Heiss

  On mid-day Wednesday, the always colorful Oracle Evangelist Simon Ritter demonstrated Java on the Raspberry Pi at his session, “Do You Like Coffee with Your Dessert?”. The Raspberry Pi consists of a credit card-sized single-board computer developed in the UK with the intention of stimulating the teaching of basic computer science in schools. “I don't think there is a single feature that makes the Raspberry Pi significant,” observed Ritter, “but a combination of things really makes it stand out. First, it's $35 for what is effectively a completely usable computer. You do have to add a power supply, SD card for storage and maybe a screen, keyboard and mouse, but this is still way cheaper than a typical PC. The choice of an ARM (Advanced RISC Machine and Acorn RISC Machine) processor is noteworthy, because it avoids problems like cooling (no heat sink or fan) and can use a USB power brick. When you add in the enormous community support, it offers a great platform for teaching everyone about computing.”Some 200 enthusiastic attendees were present at the session which had the feel of Simon Ritter sharing a fun toy with friends. The main point of the session was to show what Oracle was doing to support Java on the Raspberry Pi in a way that is entertaining and fun. Ritter pointed out that, in addition to being great for teaching, it’s an excellent introduction to the ARM architecture, and runs well with Java and will get better once it has official hard float support. The possibilities are vast.Ritter explained that the Raspberry Pi Project started in 2006 with the goal of devising a computer to inspire children; it drew inspiration from the BBC Micro literacy project of 1981 that produced a series of microcomputers created by the Acorn Computer company. It was officially launched on February 29, 2012, with a first production of 10,000 boards. There were 100,000 pre-orders in one day; currently about 4,000 boards are produced a day. Ritter described the specification as follows:* CPU: ARM 11 core running at 700MHz Broadcom SoC package Can now be overclocked to 1GHz (without breaking the warranty!) * Memory: 256Mb* I/O: HDMI and composite video 2 x USB ports (Model B only) Ethernet (Model B only) Header pins for GPIO, UART, SPI and I2C He took attendees through a brief history of ARM Architecture:* Acorn BBC Micro (6502 based) Not powerful enough for Acorn’s plans for a business computer * Berkeley RISC Project UNIX kernel only used 30% of instruction set of Motorola 68000 More registers, less instructions (Register windows) One chip architecture to come from this was… SPARC * Acorn RISC Machine (ARM) 32-bit data, 26-bit address space, 27 registers First machine was Acorn Archimedes * Spin off from Acorn, Advanced RISC MachinesNext he presented its features:* 32-bit RISC Architecture–  ARM accounts for 75% of embedded 32-bit CPUs today– 6.1 Billion chips sold last year (zero manufactured by ARM)* Abstract architecture and microprocessor core designs– Raspberry Pi is ARM11 using ARMv6 instruction set* Low power consumption– Good for mobile devices– Raspberry Pi can be powered from 700mA 5V only PSU– Raspberry Pi does not require heatsink or fanHe described the current ARM Technology:* ARMv6– ARM 11, ARM Cortex-M* ARMv7– ARM Cortex-A, ARM Cortex-M, ARM Cortex-R* ARMv8 (Announced)– Will support 64-bit data and addressingHe next gave the Java Specifics for ARM: Floating point operations* Despite being an ARMv6 processor it does include an FPU– FPU only became standard as of ARMv7* FPU (Hard Float, or HF) is much faster than a software library* Linux distros and Oracle JVM for ARM assume no HF on ARMv6– Need special build of both– Raspbian distro build now available– Oracle JVM is in the works, release date TBDNot So RISCPerformance Improvements* DSP Enhancements* Jazelle* Thumb / Thumb2 / ThumbEE* Floating Point (VFP)* NEON* Security Enhancements (TrustZone)He spent a few minutes going over the challenges of using Java on the Raspberry Pi and covered:* Sound* Vision * Serial (TTL UART)* USB* GPIOTo implement sound with Java he pointed out:* Sound drivers are now included in new distros* Java Sound API– Remember to add audio to user’s groups– Some bits work, others not so much* Playing (the right format) WAV file works* Using MIDI hangs trying to open a synthesizer* FreeTTS text-to-speech– Should work once sound works properlyHe turned to JavaFX on the Raspberry Pi:* Currently internal builds only– Will be released as technology preview soon* Work involves optimal implementation of Prism graphics engine– X11?* Once the JavaFX implementation is completed there will be little of concern to developers-- It’s just Java (WORA). He explained the basis of the Serial Port:* UART provides TTL level signals (3.3V)* RS-232 uses 12V signals* Use MAX3232 chip to convert* Use this for access to serial consoleHe summarized his key points. The Raspberry Pi is a very cool (and cheap) computer that is great for teaching, a great introduction to ARM that works very well with Java and will work better in the future. The opportunities are limitless. For further info, check out, Raspberry Pi User Guide by Eben Upton and Gareth Halfacree. From there, Ritter tried out several fun demos, some of which worked better than others, but all of which were greeted with considerable enthusiasm and support and good humor (even when he ran into some glitches).  All in all, this was a fun and lively session.

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• Raspberry Pi Now Shipping with 512MB RAM; Still Only $35

  - by Jason Fitzpatrick

  Fans of the tiny Raspberry Pi will be pleased to hear the new version of their Model B board now ships with 512MB of RAM (up from the previous 256MB). The best part about the upgrade? The price point stays at $35 a board. From the official Raspberry Pi blog: One of the most common suggestions we’ve heard since launch is that we should produce a more expensive “Model C” version of Raspberry Pi with extra RAM. This would be useful for people who want to use the Pi as a general-purpose computer, with multiple large applications running concurrently, and would enable some interesting embedded use cases (particularly using Java) which are slightly too heavyweight to fit comfortably in 256MB. The downside of this suggestion for us is that we’re very attached to $35 as our highest price point. With this in mind, we’re pleased to announce that from today all Model B Raspberry Pis will ship with 512MB of RAM as standard. If you have an outstanding order with either distributor, you will receive the upgraded device in place of the 256MB version you ordered. Units should start arriving in customers’ hands today, and we will be making a firmware upgrade available in the next couple of days to enable access to the additional memory. We’re excited to get our hands on a new board and try out Raspbmc with that extra RAM. HTG Explains: What is the Windows Page File and Should You Disable It? How To Get a Better Wireless Signal and Reduce Wireless Network Interference How To Troubleshoot Internet Connection Problems

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