avr

USB Cherry MX Numpad

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Almost a year ago, I bought my first mechanical keyboard. It's a Filco Ninja Majestouch-2 Tenkeyless (with Cherry MX Brown switches). It's an absolutely amazing keyboard to type on and is built like a tank, well worth the admittedly shocking price. However, the "tenkeyless" in the name means that it does not have a numpad. The keyboard is available with a numpad aswell, but the reason why I did not want one is that I am left-handed, and much prefer the numpad to be on the left side of the keyboard. A normal numpad would be almost useless for me.

Another reason why I got the tenkeyless version was this: not having a numpad also gave me an excuse to build my own! It's taken a year, but I finally managed to get around to doing it. That is what this post is all about.

AD9833-based USB Function Generator

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One tool that I've been missing at my lab at home is function generator. They tend to be a bit expensive, so I haven't bought one. I thought this might be a good opportunity to try and make one myself. I found a pretty common DDS (direct digital synthesis) chip, called AD9833. Then just strap a USB-enabled AVR micro there and maybe some analog electronics.

This board doesn't do any of the special analog magic to allow for variable amplitude or offset for the signal. The output is fixed to 0-4v. I'm planning to make another completely analog board for adjusting amplitude and offset.

Capacitive Touch Sensing with AVR and a Single ADC Pin


I've been thinking of a project that needs a little bit more elegant user interface than your usual push buttons. Partly inspired by a video blog on Dave Jones' EEVblog, I decided to look into capacitive touch buttons. The big issue unfortunately for me was that you usually need a separate chip for capacitive touch sensing. With some tricks, you can however use a normal microcontroller to do the job. Even using only a single pin and resistor.

Wireless Motion Sensor

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Wireless stuff is fun! If you look at the picture above, the thing to the right, clamped to a vice, is a motion sensor (PIR sensor) that has a small addition on it's back. That addition is a small PCB that I designed, milled and soldered recently, with an ATmega microcontroller and a cheap radio-module on it. The thing to the left is a spectrum analyzer showing that the device is indeed sending radio signals. In the background you can also see a radio-controlled RGB light controller, but that's a story for a later time.

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