May 19

Export Board from Altium for OSHPark

Here’s a quick guide on exporting a board from Altium Designer 14 to be made by OSHPark.

1. Go to Design -> Layer Stack Manager
2. Set your stackup to be this:


This information was derived from this FAQ.
3. Go to Project -> Compile PCB Project.  Fix any errors that could cause a problem.
4. Go to File -> Fabrication Outputs -> Gerber Files
5. Under ‘General’, set the units to be ‘Inches’ and the Format to be ‘2:4’
6. Under ‘Layers’, select the following layers:

  • Top Overlay
  • Top Paste
  • Top Solder
  • Top Layer
  • Bottom Layer
  • Bottom Solder
  • Bottom Paste
  • Bottom Overlay
  • Mechanical 15(assuming that you have drawn your board outline on mechanical 15)

Now export, save as <projectname>.cam

7. Go to File -> Fabrication Outputs -> NC Drill.  Use the following settings:

  • Units: Inches
  • Format: 2:4
  • Leading/Trailing Zeros: Suprress trailing zeros
  • Coordinate Positions: Reference to relative origin
  • Other: Optimize change location commands

Save as <projectname>

8. With the file selected, go to File->Export->SaveDrill.  Set the extension to be .xln

9. Go to your project folder, there should now be a sub-folder called ‘Project Outputs for <Project Name>’.  Grab the following files:

  • *.xln
  • *.GBL
  • *.GBO
  • *.GBP
  • *.GBS
  • *.GKO(re-name the .GM15 file to be .GKO)
  • *.GTL
  • *.GTO
  • *.GTP
  • *.GTS

Put these all into a .zip folder.

10. Upload the .zip folder to OSH Park.

11. Have fun!

Apr 23

WMP54G on Windows 7

So I just upgraded my computer today with an nVidia 970GTX so that I can play Grand Theft Auto V.  However, this caused two problems:

  1. I couldn’t fit the card into my case
  2. The new case had a different configuration, so I had to move my wireless card to a different PCI slot.

When that happened, Windows freaked out.  Completely lost its sense of drivers, so my wireless wasn’t working.  How to get it to work(note: this is from memory, some of this wording is not exact):

  1. Go to Device Manager
  2. Right-click on the network device, go to ‘Update Driver Software’
  3. Go to ‘Browse My computer’
  4. Click ‘Let me pick from already existing drivers’
  5. Go to ‘Network Devices’
  6. Scroll down to Ralink Technology
  7. Select the ‘Wireless LAN a/g PCI card’
  8. Install the drivers
  9. Get on the internet!

Now time for GTA V!

Feb 03

Web Design and Programmers

On a project at work, we’re starting into web development from being entirely desktop applications.  It’s a new thing to learn because of that.  We’re working with a contractor, who is creating the majority of the website for us.  He has suggested, and we have implemented, a REST-based service for sending data to and from the server.  Fortunately, making a REST-based web service in Java is very easy using Genson and JAX-RS.

However, this post is not about that.  It is about web technologies in general.  Originally, I spent a fair amount of time researching different web technologies that use Java as the backend, and I came up with a few such as JSP, JSF, as well as some frameworks, such as PrimeFaces.  We’re not using JSF technology at the moment, but that’s not really the point either.

There are a lot of different web technologies out there, and each has its own pros and cons.  My real question here is why do we treat web design as separate from programming the website?  While researching the advantages/disadvantages of a REST-only website, I came across this good post on programmers.SE about the pros and cons, which then led me to this interesting post about using tag libraries in web pages.  Essentially, what this boils down to is:

The benefit here is that web designers are supposed to be able to work with these tags, or at least that’s what they say. In practice, in all my years of software development and programming, I have yet to ever see this magical unicorn walk out of the shadows and into the sunlight.

My question here though is: why are we treating web development in a different light than we are treating desktop application development?

When developing a desktop application, generally the programmers are the people who create the design.  Even if somebody creates the design in a GUI designer, the programmer has to be involved in how to tie all the events together – they don’t exist in separate paradigms, which is what web technologies seem to do.

In fact, I make all of my Java GUIs by hand.  I have never made a QT gui by hand, but from the generated code that I have looked at it follows a very similar programming model(composite design pattern).  What exactly is preventing a web designer from doing code, and what is preventing a programmer from making a website?

It seems to me that this is not something where the programmer and the web designer are two different people.  What seems to be better would be to have people that can straddle both areas.  After all, we are generally not pigeon-holed into just one area.  If you work mostly on backend code, it is not unreasonable to also touch the GUI code at some point, so you must know how the GUIs are set-up.  But for web development, this seems to be just the opposite.

Perhaps what we need is a swing-like web framework that you don’t need to make any HTML files for, just create the entire website through code.  This sounds complicated, and I don’t know if it would solve the problem.

Jan 19

PIC32 and I2C

I’ve been struggling with Microchip’s plib library trying to get I2C working.  First, the example I2C code is horrible.  Second, I’m not even sure what sample hardware from Microchip actually uses it.  It’s just so confusing.

Anyway, there are a few things to note here about the I2C library and the quirks that it has:

  • Make sure that you have pull-up resistors on the I2C bus.  This was problem #1.
  • Make sure you configure all pins as digital, if they are analog pins.  This was problem #2.
  • There are two methods you need to acknowledge the I2C: I2CAcknowledgeByte and I2CByteWasAcknowledged.
  • When reading a byte from the bus when you are the master, you need to call I2CReceiverEnable for each byte that you need to get.

These functions are not very special; the problem is that they are poorly documented.  For the most part, the plib functions simply access the registers directly in memory and return an appropriate value after checking the bits that may be set as a side effect.  It’s not particularly hard, they are just oddly named often times.

Anyway, you can see more about this both here and… some other place on the Microchip forums, I can’t find it now.

Hope that helps.

Dec 22

Adventures in accidental chown

So earlier today I had to get Virtualbox up and running, and it was complaining about permissions not being set right.  For some reason, the permissions on my /usr directory were slightly messed up and not owned by root.  So, I did:

sudo chown root:root /usr

That didn’t fix the problem.  Going into the /usr directory, I also noticed that a few of the other folders weren’t owned by root.  So, let’s just go fix everything at once:

sudo chown -R root:root /usr

Okay, now let’s try starting Virtualbox!

Virtualbox now complains about not being setuid.  Okay, fine.  Let’s reinstall virtualbox, since it says that should fix it.

sudo dpkg -i virtualbox.deb
sudo: must be setuid root



Turns out, doing the chroot dropped the setuid bit from all binaries in the /usr directory.

To fix this, you’ll have to boot from a rescue disk/CD of some kind, and change the permissions on sudo:

chmod 4755 /path/to/mounted/filesystem/usr/bin/sudo

Other programs will also be messed up at that point, but now that you have sudo you can change the permissions to what they should be, and/or reinstall. 🙂

Oct 29

The Definition of Programming

Programming (noun): The art of putting together software that other people have written and breaking it in new and exciting ways.


It’s rare that you will have to create something entirely new from scratch.  So, it’s always a matter of taking things that have already been made and putting them together.

Conceptually, this a pretty simple idea.  In practice however, it’s much more complicated.  You need to know how exactly all the parts come together.  This is why good documentation of libraries is very important.  Without good documentation, it’s next to impossible to integrate a needed library.  You almost have to become an expert in how the library works, which rather defeats the purpose of using a library in the first place! This is very annoying.  Please, write good documentation!


Also, it seems that ‘programming’ could be both a noun and a verb, but Webster’s only defines it as a noun.  Seems like a bit of an oversight.

Aug 11

GNOME 3 Plugins: Settings

This post is going to be based partially on the source of Coverflow Alt Tab, plus some of the source files that are already included in GNOME 3.

Also, a few notes here: it appears at this time that there is no way to easily import your schema into the GSettings backend.  This may be added at a future time.  So, any settings that you make will essentially be unstructured and possibly break if somebody messes around with them.

The first thing for us to do is to create a new XML schema for us. This schema holds the keys to our values, as well as default values and descriptions.  There’s some documentation on the GNOME website, so i will only go over a small portion of what is there, given that I only understand a small portion. 🙂

For our purposes, we will define two keys: one string key which will be the text to display, and a boolean value that we will mess around with later.  For now, let’s define the XML schema:

<?xml version="1.0" encoding="UTF-8"?>
  <schema id="com.rm5248.testplugin" path="/org/gnome/shell/extensions/rm5248/">
    <key type="s" name="hello-text" >
        <default>"Hello, World!"</default>
        <summary>The text to display</summary>
        <description>The text to display</description>
    <key type="b" name="wait" >
        <description>Do you wait until OK?</description>

This is pretty straightforward: you have a schema with a name(com.rm5248.testplugin) and two keys, a string value called ‘hello-text’ and a boolean vaue called ‘wait’.  Once we have written the XML file, we need to generate the binary version of it.  To do that, simply use the glib-compile-schemas tool:

glib-compile-schemas schemas/

Now that we have our compiled schema, it’s time to retrieve settings from the GSettings database.  In order to do that, we will need this lib.js file from CoverflowAltTab.  From the copyright, it appears to be from the GNOME sources, however I have been unable to find where it originally comes from.

Now that we have our schema compiled and in the schemas/ directory, it’s a very simple process to get the default settings(as we haven’t changed them at all.).  In fact, here’s the entire code:

const Gio =;
const ThisExtension = imports.misc.extensionUtils.getCurrentExtension();
const Lib = ThisExtension.imports.lib;

const RM_SCHEMA = 'com.rm5248.testplugin';
const TEXT_KEY = 'hello-text';
const BOOL_KEY = 'wait';

let settings = null;

function init() {
    // Create the new settings
    settings = Lib.getSettings( RM_SCHEMA );

function enable() {
    log( settings.get_string( TEXT_KEY ) );
    log( settings.get_boolean( BOOL_KEY ) );

function disable() {

For now, we’re just printing out the settings to the console, which is not very useful. We’ll expand this in a bit, but before we do that let’s make a GTK widget to set the settings.  Looking at the GNOME documentation, we see that we can change settings by having a prefs.js file with a method buildPrefsWidget.

A quick note before we get started here: when constructing a C object, the parameters to the object(in the {} syntax) are properties to set on the object.  Take for example the properties on GTKLabel: if you want to set the ‘angle’ property when constructing, you would do:

new Gtk.Label( { angle: 20 } );

Do this for all the properties that you wish to set when you create the object.

Now, moving on to the actual code of the prefs.js file.  Everything here is fairly straightforward if you’ve done GTK+ programming before.  Here’s the code that will pop up a GTK+ widget:

function buildPrefsWidget(){
    let frame = new Gtk.Box( { orientation: Gtk.Orientation.VERTICAL, border_width: 10, spacing: 10 } );

    //There are two settings, so we will have one that changes the text and one that changes
    //the boolean value.
    //Create an EntryBuffer to store the text in
    let entryBuffer = new Gtk.EntryBuffer( { text: settings.get_string( TEXT_KEY ) } );
    let textBox = new Gtk.Box( { orientation: Gtk.Orientation.HORIZONTAL, spacing: 10 } );
    let textLabel = new Gtk.Label( { label: "Hello text", xalign: 0 } );
    let textEntry = new Gtk.Entry( { buffer: entryBuffer } );
    //Gtk.Entry implements GtkEditable interface, which is where the 'changed' signal comes from
    textEntry.connect( 'changed', function( widget ){
      settings.set_string( TEXT_KEY, widget.get_text() );
     } );
    textBox.pack_start( textLabel, true, true, 0 );
    textBox.add( textEntry );

    //Let's change our boolean value now
    let boolBox = new Gtk.Box( { orientation: Gtk.Orientation.HORIZONTAL, spacing: 10 } );
    let boolLabel = new Gtk.Label( { label: "Do we wait?", xalign: 0 } );
    let boolRadio = new Gtk.Switch( { active: settings.get_boolean( BOOL_KEY ) } );
    //Gtk.Switch has an 'activate' signal, but don't connect to that directly.
    //Instead, the docs say to use the 'notify::active' signal
    boolRadio.connect( 'notify::active', function( widget ){
        settings.set_boolean( BOOL_KEY, widget.get_active() );
     } );
    boolBox.pack_start( boolLabel, true, true, 0 );
    boolBox.add( boolRadio );

    frame.add( textBox );
    frame.add( boolBox );

    return frame;

To test this out, re-load the shell (ALT+F2, r, enter), and open up gnome-tweak-tool.  Under ‘Extensions’, there should now be a small cog for the ‘settings example’ extension.  If you open that up, you should see the two settings that we made: one for the text, and one for the boolean value.  By changing these values, you can change what the extension will print out when the plugin is loaded.

You can also use dconf to see the values directly, once you have saved them first.  Change a value with gnome-tweak-tool, open up dconf and navigate to /org/gnome/shell/extensions/rm5248/, and you will see the settings that you have made.  Remember though, they only appear there if they are different from the defaults; this may not be true for all programs, but it is true for gnome-shell extensions.

You may find the complete source here.

Aug 08


So I’m working on this settings stuff for GNOME 3, and I attempted to compile a new gsettings schema.  So I make my XML schema, and run glib-compile-schemas, and it comes back at me:

schemas/com.rm5248.testplugin.gschema.xml: 0-1:unknown keyword. This entire file has been ignored.

Okay… so I look at the file, and everything looks fine.  I can’t see anything wrong with it.  I go back and forth, trying different things, until I narrow it down to this key:

<key type="s" name="hello-text" >
        <default>Hello, World!</default>
        <summary>The text to display</summary>
        <description>The text to display</description>

Commenting this out makes it work fine. So I look at the documentation for the schemas, and nothing immediately pops out at me, until I see the following:

One possible pitfall in doing schema conversion is that the default values in GSettings schemas are parsed by the GVariant parser. This means that strings need to include quotes in the XML.

So I change the XML to be the following:

<key type="s" name="hello-text" >
        <default>"Hello, World!"</default>
        <summary>The text to display</summary>
        <description>The text to display</description>

What. The. Hell.

Why do string values have to be highlighted?  That doesn’t make a lot of sense.  There shouldn’t be any reason for that.  It is still valid XML, but who does it that way? Moreover, WHY DOESN’T THE ERROR MESSAGE GIVE ME ANY USEFUL INFORMATION? That is possibly the worst error message ever. Okay, it’s been ignored, BUT WHY THE HELL HAS IT BEEN IGNORED?! Is it really that hard to provide good error messages? Also, what the hell is the “0-1”? Is it some sort of bizzare error code or what? There’s nothing to imply that the reason it failed was because it was missing a quote – at least if it gave a line number that would let me clue in to what is going on, but apparently they can’t be bothered to do that.