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Microcontrollers for nifty projects

You can have a lot of fun with a bit of processing power, some analog to digital conversion capability, and some ‘glue’ such as memory, software, and support circuitry. On one end of this type of device is the ‘computer on a chip’ and on the other is the custom programmed hardware. In between there are a bunch of options that balance off cost and capability. Two of the current favorites for the hobbyists are the Arduino and the PICAXE.

The VK5JST Aerial Analyser uses a PICAXE and is a rather typical microcontroller project. It has an oscillator feeding a bridge to measure antenna characteristics. Three voltages from that bridge are fed to ADC ports on the PICAXE to calculate reactance and resistance of the antenna using standard trigonometry calculations.

The PICAXE project is geared towards educational activities like building robots. It is not the fastest nor most compute capable microcontroller but it is cheap and will do the job for interactive devices such as the antenna analyser. It has a BASIC interpreter built into the microcode that makes access and use of its ports a simple affair. The Arduino is a bit faster, more capable, and more difficult to program.

Where this is going is seem with the Digispark. That’s an effort to make a USB dongle with an Arduino cheap enough to play with. The Rasberry Pi at about twice the price (~ $25) not only has USB but also Ethernet and Video but is perhaps a bit short on built in customizable ports.

I don’t know the selection criteria VK5JST used for the PICAXE but it does illustrate a very simple solution that is adequate for its purpose. The fact that several hams have updated and modified the software says something about its complexity as well. Since this particular microcontroller will provide PWM motor control, it should also be adaptable to manipulate capacitors in a tuner, for instance. The antenna analyzer is a good example of just what you can do.

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