OFF Topic: generating 20- 60 HZ

elektroKid · Guest

Hi!

Sorry for posting this question on your forum but i think that someone of you gurus knows the right answer.

I have 16F914 and am using internal osc.

What hardware parts ( and how to connect ) do i need for generating 20 - 60 HZ signal from one mcu pin ?

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

http://www.ccsinfo.com/forum/viewtopic.php?t=26636&highlight=sine+wave

SherpaDoug · Joined: 07 Sep 2003 Posts: 1640 Location: Cape Cod Mass USA

It makes a big difference if you really need a sine wave, or if a simple square wave will do. Also do you need to be able to change the frequency on the fly? If so then simple low pass filtering of a square wave won't work as 60Hz is the third harmonic of 20Hz. You will have to tune the filter.
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elektroKid · Guest

This is the link that i have get from the guys at electro forum.
h**p://www.min.at/prinz/oe1rib/DDS/SineDDS.htm

@ SherpaDoug
It is sine wave and i will have to change frequency on the fly, but i was thinking to make all this thru program ( you know, one buttton press will encrease the frequency for 5 HZ or something like this).

What do you think of the schematisc from the electro forum. Is there simpler way..

SherpaDoug · Joined: 07 Sep 2003 Posts: 1640 Location: Cape Cod Mass USA

That schematic looks OK, but you may have to get a newer D/A converter. Look at the chips by Maxim (www.maximic,com), they give out free samples too.
For the software look into "numerically contrilled oscillator". That is a clever sort of algorithm that does just what you want.
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The search for better is endless. Instead simply find very good and get the job done.