How to make a tuner that measures frequency?

asian123

We are two students that are currently trying to make a guitar tuner using the propeller chip. We are trying to measure the frequency of sounds produced by guitars. However, we are not sure how the analog to digital converter on the propeller chip works. Are there certain ports that are assigned to convert analog to digital on the propeller? Is the analog to digital converter built into the propeller, or do we have to get one ourselves? If we were to use a microphone to receive the sounds, how would we wire it to the propeller?

Bobb Fwed

There are no built in ADCs. You can create an ADC using a couple capacitors (though I think it's either slow and high res, or fast and low res -- or somewhere in between), but for speed and resolution, you should get an ADC IC. I recomend the MCP320X or MCP300X (replace X with the number of channels you want). Both can get up over 100KHz (above the somewhat standard 96KHz or standard 44.1KHz). And so it's your choice of either 12 or 10 bit.

I even have an object that will tell you the frequency of the input using these ICs...here: http://obex.parallax.com/objects/488/