This is my first post to this forum and I am very new to working with electronics for custom purposes. I have a question regarding the use of a 4x4 keypad matrix. I am building a custom PC case and I already have plans to integrate servos & servo controllers; this part I have a comfortable grasp on. I would also like to incorporate a 4x4 keypad into the design to startup & shut down the PC. The problem is that I ahve no idea what it would take to implement this idea. If anyone could shed some light on what materials I would need, and how I could program this thing, I would greatly appreciate it. I do have some programming background in VB, so I believe I can decifer some code examples. But, comments within the code would be greatly appreciated. Here's a link to my custom PC case I am building if you'd like to check it out.
As always, I am more open to bulding my own stuff rarther than buying kits. All options will be considered though.
There was one other NandV of basic stamps article I was looking for that describes, using SX/B, how to code a standard 4x4 matrix keypad. But I could not find it, feel free to look for yourself.
Here is a simple 1-wire output circuit to interface a matrix-type keypad using only one I/O pin from the micro of your choice. This particular circuit creates a pulse width output for each key. I’ve also seen one without a 555 timer that simply senses the voltage through an analog input. When a key is pressed, it creates a unique resistance that the micro can detect.
Another approach would be to hook it up through something like a Matrix Orbital LCD. One example is the GLK12232-25. This graphic LCD allows you to connect a keypad matrix of up to 5x5 and can communicate with your processor through either RS232 or I2C.
If for example you connect it up by RS232, when you press a button on the keypad it will generate an ascii character that gets sent back through the attached serial port at the current baud rate.
