Andrew Krause's book, Foundations of GTK+ Development has been released. I did some of the technical review work on this book and can say that Andrew has done a fine job. As far as I am aware, it is the only GTK+ book currently available for GTK+ 2.x. It covers the new widgets like notification icon, print dialog, recent files, etc.
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If you a home hobbiest such as myself, having an oscilloscope is ideal, but may not be economically feasible. However, there is a free option available. xoscope For Linux is a GTK application which allows you to view signals through your PC's sound card (thus limiting the range to audio frequencies dependent upon the sound card being used). This can come in handy for robotics type hobby projects. Additionally, the author (Tim Witham) has provided a buffer hardware circuit to buffer the proble similar to a true oscillosope and protect your PC's Line In from excessive voltages.
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| FailureBot 5 - Complete Robot | FailureBot 5 Following A Line |
Though an input can be from any number of sources, one of the mose common and the easiest to implement, would be a swith. Due to mechanical properties of a switch, when a switch is closed, there is a period of time in which the electrical connection "bounces" between open and closed. To a microcontroller, this "bouncing" can be interpreted as multiple button pushes. Therefore, we must either build a circuit to supress the "bouncing" or we must do so in our software. This is known as "debouncing a switch".
The ATMega8 AVR is shipped with it's clock source configured to the internal 1MHz RC oscillator (see: "Calibrated Internal RC Oscillator" in the datasheet p.30). This configuration works fine for many small projects where timing isn't crucial and is also convenient as it reduces parts count (1 crystal and 2 capacitors). However, you may run in to situations where you need a more accurate clock source.
The AVR family of 8-bit microcontrollers from Atmel are quickly growing in popularity for electronics and robotics hobbiests. Their major selling point for me, as opposed to the PIC microcontrollers from Microchip, are their being designed to be developed using higher languages such as C. This allows them to be developed using the open-source GNU tools (gcc). This works out especially well for me working in Linux.
Sharp's GP2D120 (and the GP2D12) is an infared distance sensor which is pretty common in the hobby robotics community. I purshaces a couple of these from DigiKey to use in a small wall-huggin robot. I spent quite a bit of time experimenting with it. This page will provide you with my schematic and AVR gcc source code for my demo file. It simply uses the ADC on an ATMega8 mpu to read the analog output of the GP2D120 and send the distance in centimeters to my laptop through the serial port (actually, through a USB to serial converter).
In this example code, I show how to use the GtkFontSelectionDialog and the GtkColorSelectionDialog using C/GTK+ and libglade. Both dialogs as well as the main window are in the gui.glade file created by Glade.
This is a simple Linux application using GTK+ and libglade to demonstrate some very simple dialog boxes. The application's interface is created in Glade and accessed using libglade, however, the dialog boxes are implemented entirely in GTK+ code since they're so easy to implement that way. These dialog boxes are from the GtkMessageDialog widget, which is a derivative of the GtkDialog widget.
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