WebDMA 0.2 is now available for download at the WebDMA project site. Using C++ operator overloading, WebDMA provides proxy objects that your application can use as normal variables which can be manipulated or displayed by your application via a configurable jQuery/javascript powered AJAX-enabled Web 2.0 interface hosted by an lightweight embedded web server. Its really neat, and really useful for tuning/debugging our FRC robot. Of course, it works on Windows/Linux too.
This is a better packaged version of WebDMA, with a few feature improvements. Of particular interest to FRC teams, I have released an installer that installs the object files for WebDMA on your robot, and copies the header files to the needed locations for Wind River. There is also a sample program installed for Wind River as well that allows you to control two motors on your robot with the web interface as a demo. All you need to do to use WebDMA on your robot is install the install package to your development computer, and then run the install program to copy the necessary object files to your robot.
While this is very easy and painfree for beginners to install and use, of course I must give you this disclaimer since a program installed by the installer writes directly to the robot to install the object file:
WARNING: The provided installer will WRITE DIRECTLY TO YOUR ROBOT and modify files on it via FTP.
While I have tested this and this works just fine for our team on our cRio with no ill effects, I cannot be held responsible for your robot. This installer is not sanctioned or associated with National Instruments, Wind River, or FIRST Robotics. In particular, this may void your warranty, render your cRio useless, and COST YOUR TEAM A LOT OF MONEY.
If you are a student: DO NOT DOWNLOAD AND INSTALL THIS ON YOUR ROBOT WITHOUT ASKING THE ADULT LEADER OF YOUR TEAM.
But seriously, it works just fine for me though. And if you have problems, let me know.
I gave a presentation at work about Boost.Asio, and it came out reasonably well, so I figured I would post the slides here. Its a brief introduction to Asio and what one might use it for. Also has some basic concepts and patterns one might use while programming with Asio. Aimed for a technical audience, but nothing too detailed though.
This is just a random note that I’ve actually known for quite awhile, but I figured I would post it online somewhere where others could find it. Apparently Microsoft made a disk editor thing called ‘Disk Probe’, which came in the NT Resource Kit. I had found it available to download standalone a really long time ago, but it doesn’t appear to be available anymore. However, you can find it in the Windows XP Service Pack 2 Support Tools available from Microsoft’s download website.
Its a bit weird (at least, the NT version was), but its pretty useful if you ever find yourself playing with raw disks and you need to access them from inside windows in a pinch.
Ubuntu just released the Beta for Karmic a few days ago, so I figured that I would give it a whirl on my desktop now that I’ve switched to using Linux on my desktop fulltime. So far, I’m very happy about this upgrade, hopefully they don’t screw it up before release. :p
My first impression so far as been that its a vast improvement — and I’ve got rather old hardware, so I think thats a really positive thing. Maybe its just firefox, but it seems like to me that everything works a lot better and is more responsive. The file browser in GNOME too — it used to lag quite a bit while browsing through my drive — now it seems to work exactly as I might expect. I know they’ve been touting a really quick boot time, and it feels a little bit faster, but I’m not quite sure about that. I haven’t bothered timing it or anything though.
There were two annoying things about the upgrade. First, X didn’t work at first and just kept blinking in a loop — but that was totally my fault, since I’m using the latest NVidia drivers, and forgot to reinstall before I rebooted. However, a quick boot into a command prompt and reinstalling the drivers got it all working again. The second thing that is a bit weird is they must have changed the font or the way its anti-aliased now, since everything looks a bit more.. blurry. Or something, I can’t quite put my finger on it. I’m starting to get used to it, but its too bad the fonts aren’t a bit crisper.
FWIW: Keep in mind that I’m using rather old hardware on my desktop, but XP always worked well on it! I’m using an Athlon 3000+ with a triple-monitor setup on two NVidia 6600 cards (one PCI, one AGP). 2GB RAM, and some various SATA and IDE disks.
I’m taking a workshop at work taught by David Abrahams, and he briefly mentioned this thing called XSMELL, which apparently allows you to write XML-like things in pure C++ code. From the README:
Congratulations! You have in your hands the MOST BRILLIANTEST C++ XML CREATION
LIBRARY EVER CREATED.
...
And you no longer have to worry about generating malformed XML! After spending
hours fighting obscure C++ compiler errors, you’ll be 100% certain that your
XML is correct.
I’ve always been a fan of PuTTY, the Windows terminal emulator. Its extremely simple to use and is one of the main reasons I like using windows to maintain linux systems. One of the biggest things I like about PuTTY is that it allows you to copy on highlight, and paste into the window by right clicking. It saves so much time and is really easy to use.
So when I moved my desktop to Ubuntu this summer and got rid of XP, this has really been one thing that I really miss. However, I just found a blog post that explains copy/paste in X, and that a similar system actually exists system-wide, except it uses the ‘middle’ mouse button instead.
Seriously, this is an awesome feature that I did not know about, and definitely am going to take advantage of. Now I just need to remap one of the extra buttons on my mouse to be the middle one so its more convenient to use…
If you read my previous post, I was talking about this new open source library I’ve created that allows you to embed a web server in your C++ application so that you could modify variables inside of it. I had created it for our FIRST Robotics team so that we could use it to tune things on our robot (and its been extremely useful for that) and use it for simple data acquisition. Of course, driving a robot is nothing more than changing variables… so I thought it would be a neat demo to set it up so that it could be driven by the web interface.
Here’s a video of our robot being controlled via the WebDMA interface:
When walking around during the Boston Regional, I had been talking to some people about code, and they mentioned that LabView was great because they could tune their PID controllers on the fly while the robot was operating. So I thought to myself, “why can’t I do this with C++?”. And… so I did. WebDMA was created to allow our FIRST Robotics team to tune our robot in an easy to use and intuitive way via any modern web browser.
Using C++ operator overloading, WebDMA provides proxy objects that your application can use as normal variables which can be manipulated or displayed by your application via a configurable jQuery/javascript powered Web 2.0 interface hosted by an lightweight embedded web server.
Despite that WebDMA was specifically created for use in FIRST Robotics on the NI-cRio/vxWorks platform, it uses the Boost ASIO portable networking library and Boost Thread portable threads library and is usable on any platform supported by these Boost libraries (tested on Boost 1.38, requires a patch for vxWorks).
The FIRST Robotics Competition is using the National Instruments cRio platform for the robot controller this year, and the operating system on it is vxWorks 6.3. After we participated in the competition, I had gotten a great idea involving putting a webserver on the robot so that it would be easier to tune various parameters on the robot (which I will be releasing soon).
I decided to use Boost::Asio for the networking layer since I had been meaning to write something using it for awhile anyways, and since its portable I could do the initial development on my home computer and then easily (at least, ideally) transfer it to another platform. I also decided to use Boost::Thread for the same reason. If you haven’t used Boost before, I highly recommend it — it has a lot of well-written and useful C++ header-only libraries.
Unfortunately, vxWorks is a bit different than ’standard’ POSIX/*nix systems, so there are a number of patches one needs to make to Boost 1.38.0 in order to compile. I’ve submitted the patches to boost, so hopefully by the time 1.39.0 rolls around you won’t need this.
You can download the full patchset needed from my FRC resources page. Download it.
For years I’ve hated cygwin (not for any particular reason, I just don’t like it) and have generally avoided using it because of that — but I’ve finally found a good alternative if you want useful *nix tools on Windows. Its called GNUWin32 and its a bunch of GNU utilities that have been ported to windows, and they’re quite lightweight also.
Its pretty sweet, I’ve actually had grep installed on my computer for quite awhile now, and just recently started installing more of these packages as my needs have evolved. I’d highly recommend it. The key thing to do is to add the bin directory to your path, so that way its accessible from cmd by default without having to screw around with typing out the full path name or anything.
