Archive for the ‘Software’ Category

« Older Entries

Changing variables using a web interface and embedded HTTP server

Tuesday, April 21st, 2009

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).

A non-functional (but very shiny) demo of the interface is available at http://www.virtualroadside.com/botface/index.html

Visit the Google Code project site for WebDMA

Update: Go here for a video: http://www.virtualroadside.com/blog/index.php/2009/04/25/webdma-demo-video/

Posted in FIRST, Howto, Innovation, Javascript, Software, WebDMA, jQuery | No Comments »

WPILib Test Harness Released!

Saturday, March 14th, 2009

So after *far* too much time spent on this, I am happy to announce the release of my WPILib Test Harness! For those who aren’t aware, WPILib is the name of the C++ library that FIRST gives to FIRST Robotics Teams to control the robots. The control system is a PowerPC running on a cRio platform designed and produced by National Instruments.

It had occurred to me towards the end of the build season this year that it was really annoying that I could only easily test code while our team was meeting, and of course I stay up late (as evidenced by this post time). So I wrote some stubs, but at some point I realized it would just be easier to make a giant stub for WPILib, since its just a set of classes with some hardware interfaces. It was extremely useful, and as I evolved it I was even able to find bugs in WPILib and the program for our bot.

At some point I decided to bring it in the direction that it is now, and I’ve spent the last week adding things and making the GUI a bit shinier. I’m pretty happy with the results so far, but theres a long way to go before every bot program will run under it. There’s a lot of things that do work, but there’s also a lot of things that don’t work.
(more…)

Posted in FIRST, Software, WPILib | 1 Comment »

Debug STL errors with __GLIBCXX_DEBUG

Friday, March 13th, 2009

Ever got one of those *really* annoying glibc errors that don’t give you a whole lot of information except “something bad happened, and it was memory related, but we’re not going to tell you where the problem is!”? You know, in the form of

*** glibc detected *** ./test: double free or corruption (out): 0x0000000001e52440 ***
======= Backtrace: =========
/lib/libc.so.6[0x7f27a9fd5a58]
/lib/libc.so.6(cfree+0x76)[0x7f27a9fd80a6]
./test[0x401e51]
./test[0x401e83]
./test[0x402118]
./test[0x402159]
./test[0x40155b]
./test[0x40167d]
/lib/libc.so.6(__libc_start_main+0xe6)[0x7f27a9f7a466]
./test[0x400cd9]
======= Memory map: ========
... and so on ...

I’ve encountered this cryptic and annoying error (I mean c’mon, usually the memory addresses referenced in the trace don’t resolve to anything in gdb) a few times for really random and weird memory-related errors, many times when I’m doing something with the STL.

Turns out, you can define __GLIBCXX_DEBUG in your program (using -D__GLIBCXX_DEBUG on the g++ command line), and instead of an annoying message you may get an assert that is far more helpful and looks like this:

/usr/include/c++/4.3/debug/vector:267:error: attempt to access an element
    in an empty container.

Objects involved in the operation:
sequence "this" @ 0x0x7fff5ee0f420 {
  type = NSt7__debug6vectorIiSaIiEEE;
}

Now at least you know what you did wrong. However, for optimal usage you should be attached with GDB, and then as soon as the error occurs you can do a backtrace with the debugger and you should know exactly where the bug is. The only caveat is that there is a noticeable performance hit when you enable this (especially if you use the STL heavily), so in general you don’t want to define it all the time.

Hope that saves you some time! I know it helped me!

Posted in GCC, Software | No Comments »

C++ template-fu: delete_if

Sunday, November 9th, 2008

I’ve been doing a lot of work with templates lately, for my R* tree implementation (which is morphing into a R* tree and a B tree library) and some things that I’ve been playing around with for Roadnav, especially in regards to serialization.

Heres a neat snippet that I created:

template <bool>
struct delete_if {
	template <typename T>
	static void del(T t) { delete t; }
};

template <>
struct delete_if
{
	template <typename T>
	static void del(T t) { /* no-op, doesn't delete */ }
};

This uses a partial specialization to do the decision portion, and a static member template to eliminate some of the typing (you could get rid of the member template, and you would end up calling delete_if<type, delete_item>::del ).

So what this is intended for is those cases where you are implementing some generic container, and you don’t know whether the type you have is a pointer or not. You *could* use a normal bool as a parameter:

if (delete_it) delete var;

But primary problem with this is that it won’t compile if the type isn’t a pointer. So a sample of something similar to what I’m using it for is something like this:

template < typename T, bool delete_item >
class test {
public:

	~test()
	{
		// only release the item if the client specifies
		// that they want to
		delete_if<delete_item>::del(val);
	}

private:
	T val;
};

Obviously this is just a really simple example of how you can use this. One could also use boost::is_pointer to detect whether the type is a pointer, and pass *that* to delete_if while using a ‘normal’ variable to determine whether the client wants to have the item be deleted or not. I leave that as an exercise for the reader.

Posted in Snippet, Software | No Comments »

pscanf: a sscanf replacement for C

Wednesday, August 6th, 2008

In general, I like C. Pointers don’t generally bother me all that much, and its really nice to use for a lot of different things. However, its string handling SUCKS (though, printf is nice). It seems like a lot of the string routines in the standard C library are designed to screw you in the most unexpected ways possible.

So recently I’ve been struggling with processing input from a user on the command line, and I was using sscanf to attempt to do really simple string processing, and it simply wasn’t matching the correct things. After much struggling and coming to the realization that I needed to do something similar to regular expressions… I sat down and wrote the following function, and it works quite well for what I want to do.

What it does do:

  • Match arbitrary strings using a perl regex, and return the matches to you

What it doesn’t do:

  • This is not a drop-in replacement for sscanf: you need to change the format string around and (possibly) your parameters.
  • It will not return anything but a string. Thats all you get. Of course, if you format your regex correctly then you can pretty much be guaranteed that strtol/strtod/etc will work…
  • Give you any kind of comprehensive error reporting. If you want that, then just use the pcre functions directly
  • Cook your meals or do your laundry

This is released under the license contained on http://www.virtualroadside.com/software/, enjoy!

(more…)

Posted in Innovation, Software | No Comments »

Dynamic Options/Preferences Dialog Library for wxWidgets

Tuesday, April 29th, 2008

So I’ve been doing a lot of work related to my carputer lately, and one of my big focuses is getting Roadnav to be more touchscreen friendly so that I can use it as my primary GPS application. One of the biggest problems I’ve found with most applications (and Roadnav is no exception, unfortunately) is that most of the dialogs are simply too big for my screen. The preferences screen has especially stuck out as an offender here.

To solve this, over the last week I’ve created a set of generic classes that you can use in wxWidgets to create options/preferences dialogs that have a consistent feel to them, and can be easily created at runtime. Its setup in a hierarchical manner, and each layer of the menu is dynamically generated at runtime. Here’s a nice screen shot of the top level menu for your viewing pleasure.

Now, since I’m designing this for a touchscreen, right now the visual design is definitely touchscreen focused. However, its generic enough (thanks to wxWidgets sizers) that you can change the logic in the dialog to whatever you want it to be, without having to change the definition of your menus. In fact, if you do it right you can even switch the look at runtime because of all controls are created at runtime, so each one of the option classes is designed so that you can destroy its controls and then bring it back again.

Another cool option that could be implemented is loading the definitions for the options from an XML file or something similar — I’ve actually created something like that before in C# for the pGina project (see their SVN) — since everything is dynamic, it would be pretty trivial to do that.

Anyways, here’s an overview of how it works:
(more…)

Posted in Carputer, Software, wxWidgets | No Comments »

C# Oscilloscope and Analog Meter Controls

Thursday, April 3rd, 2008

I updated my C# analog meter control awhile ago (it had some bugs), but never got around to posting it online. Well, here are those updates, PLUS I integrated a C# Oscilloscope control as well! I’d put up some screenshots, but I don’t currently have a compiler installed for C# (been redoing my machine) so I can’t take any. But, it works pretty nicely except for a few non-serious bugs….

This is an ongoing set of postings documenting some of the software I developed for my senior project this fall.

Go download it.

Posted in C#, Innovation, Software | No Comments »

Analog Meter (Ammeter/Voltmeter/etc) Control for C# and .NET

Friday, January 18th, 2008

UPDATE: See my newest update, which includes a C# Oscilloscope and Analog Meter control!

This is another open source C# control that was developed for my Senior Design project. Its pretty obvious what it does from the following screenshot.

meter_ss.PNG

This is definitely a useful control for some projects, and is released under an open source license. This control implements a simple to use Analog Meter control, similar to old school analog meters used for all sorts of things. Obviously theres a lot more things that could be added to this, but this does what I need it to do at the moment. And, it looks quite nice if I do say so myself. ;) Its very adjustable as well, with integrated designer support.

Usage

Add the control to your form, and adjust the Value parameter of the control to move the needle. Pretty easy to use. There are a bunch of other options, such as adjusting the frequency of the tick marks, but they should be mostly self evident as to what they do.

Enjoy! As always, let me know if you either use this or find a bug.

Download: Link

Posted in C#, Software | 3 Comments »

Visual Studio styled Dockable Windows Component Library for .NET

Wednesday, January 2nd, 2008

Well, isn’t THAT a mouthful of a title.

This is another open source project created as a result of my Senior Design project. See, we had this nice GUI, but it seemed like it needed to be a lot more flexible than it was, since using it was really quite annoying. So, I got the idea to copy the interface from Visual Studio… since, in my opinion, the way the dockable windows work in VS is quite intuitive and useful. Some of you may cry out that there are other programs that do the same behavior… well, I copied it from VS.

So, thats what this component library implements. See a screenshot:

panes.png

As you can see, its capable of fairly complex layouts, with each element completely resizable and movable and such.  It is not quite as polished as the interface for Visual Studio, but its still quite intuitive for the user to use, and a pretty decent approximation for most projects. More importantly, its open source!

A sample executable and source code/project files are included in the download package.

Please note that you can NOT drag new panes into the form designer, as implementing the appropriate designer support seemed to be more trouble than its worth. Refer to the PaneTest project for detailed implementation, and the source code for detailed documentation.

If you find any bugs or have any comments or questions, feel free to drop me an email!

Download: Link

Posted in Announcements, C#, Innovation, Software | 1 Comment »

PSoC USB SuiteUSB .NET (CyUSB) Asynchronous Wrapper

Saturday, December 8th, 2007

This is the first of a few pieces of software I’ve written for my Senior Design project here at WMU. We created a device using a Cypress PSoC, and I wrote the user interface for the project in C#. I will be releasing a number of components from this project as open source.

If you’ve used the Cypress SuiteUSB .NET library, you’ll notice that they say asynchronously sending and receiving data to and from the device is the difficult way to access the device. Of course, one thing that contributes to the difficulty of using their interface is that its nothing like any other .NET asynchronous operations. If you have used .NET asynchronous sockets or file writing… well, you probably realize that the way Cypress decided to implement their library is definitely NOT .NET oriented, and in general is rather annoying for .NET programmers to use.

Well, it annoyed the heck out of me too, so I wrote a nice wrapper for it. Now, asynchronous sending and receiving is trivial. :)

This will allow you to wrap the EndPoints exposed by any CyUSBDevice, so that you can call .NET-style Begin/End asynchronous calls that use IO completion ports to work nicely and quickly. I do not have any benchmarks for it at this time, but I’d bet that it works faster than Cypress’s library.. of course, I could be wrong.

Does NOT support Isochronous transfers. Probably does not support ControlEndPoints either.

A set of demo code is provided.

Usage

It’s pretty trivial to use this class. Create an instance of it, then use it like any other BeginXXX/EndXXX pair in .NET. For example:

CyUSBAsyncWrapper usbComm;

// create the wrapper
private void Init(CyUSBDevice usbDevice){
	usbComm = new CyUSBAsyncWrapper(usbDevice.BulkOutEndPt);
}

// call this to begin transferring the data
private void SendData(byte [] data) {
	usbComm.BeginTransfer(data, data.Length, new AsyncCallback(EndTransfer), data);
}

// called on another thread when the transfer is complete
void EndTransfer(IAsyncResult result) {
	usbComm.EndTransfer(result);
}

Licensed under a BSD-style license. Let me know if you find any bugs.

Download: Link

Posted in C#, PSoC, Software | No Comments »

« Older Entries