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Monday, 17 March 2008

Sampling

I've had a weekend away from thinking about maladjusted fuses, and now I'm feeling much, much, better. I had occasion to add some flashing pulsing coloured lighting to the cardboard rocket that I built with my boys on Saturday morning so naturally the Arduino came out. It's amazing how something as inconsequential as some modicum of lighting can transform the lifeless cardboard tube into a dynamic play area.

While I was at it I thought that it would be easy to add some silver-foil capacitive switches which would trigger sound effects. With my collection of freebie chips in front of me now I can see that I have a brace of MCP4922 DACs that I ordered from MicroChip a while ago that remained unused. These are SPI compatible 12bit DACs which should be trivial to connect up and drive.

I'm imagining a circuit with both a DAC and some form of persistent storage on an SPI bus. I'll probably go for SD/MMC as I'm familiar with driving these and I have some solid code to work with. Most likely I'll be using a software SPI master as the DACs are unbuffered. This way I can read from the MMC and write to the DACs in an interleaved fashion which will give me greater flexibility in coding and control over playback rate.

MicroChip have a relaxed attitude to people requesting samples that I wish other companies would follow. They must go by the assumption that the more people experience using their parts the better. Word of mouth is a powerful advertising medium after all. If you've never thought of doing this I recommend giving it a try. What's to lose? :)

Another company that's sample-friendly is Dallas/Maxim - makers of the ever-so useful Max232/3 serial level converters amongst other devices.

The trick with sampling is to have the time to sit and browse the entire product range. After all you might be inspired when you see that digital potentiometer...

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About Sir Morris

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Loves: Old computers, Old Techno, Old ladies. Cake.
Hates: New computers.

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