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PIC OSCILLATOR DESIGN QUESTION

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JJFORTY

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Hi, guys

I want to build a project from the design idea magazine, but i don't know what to use to drive the frequency control inputs (4pins). As i understand these inputs have to be digital so the PIC program can compute using a look-up table and output a desire frequency. Can I use a 4 pin Digital Pot or an encoder ?

Any Suggestions?

Thanks for Looking

Source of project : https://www.edn.com/contents/images/22102di.pdf
 

wh_hsn

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Any TTL output will do
 

philba

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How do you want to control this circuit? The above design uses 16 values (0-15) on 4 pins for frequency control. Basically, you could use 4 switches to get the 16 different values. That seems a bit clumsy to me, though.

There are BCD and Hex rotary switches that encode on 4 output pins (+gnd) that would work. Pull the outputs high. Here's one example from a US surplus outfit but there are pretty widely available.


If I were doing this, I'd use a flash pic so I could change the program - probably a 16F628A. I'd also use a serial interface to control it from a PC. 16 values might not be enough...
 

    JJFORTY

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