Hello! Why not use a well traveled path, i.e., an auto detect audio circuit used precisely at the levels you are interested in. I have used this design and it works totally reliably... I've a couple years experience with it. Try the link below. http://sound.westhost.com/project38.htm Rich P -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]On Behalf Of dax2@hotmail.com Sent: Saturday, November 11, 2006 10:12 PM To: Microcontroller discussion list - Public. Subject: Re: [PIC] signal detection It doesn't have to be instantaneous in processor time. I'm willing to go a few cycles. I doubt anyone would notice a few microsecond of lag time. But, I agree with you about using an external circuit to provide a logical signal. Easier to work with. Thank you ----- Original Message ----- From: "Jan-Erik S=F6derholm" To: "Microcontroller discussion list - Public." Sent: Saturday, November 11, 2006 8:15 PM Subject: Re: [PIC] signal detection > dax2@hotmail.com wrote : > > I need to use a 12F675 to detect an audio signal of > > about a volt. Any ideas ? > > Thank you. > > > Hi. > > How fast do you have to "detect" and also how fast > do you have to detect that there is *no* audio signal ? > > The easiest way (for the PIC) is of course to build a > simple external circuit that gives a logical high or low > when detecting the signal. Then you can use a simple > digital I/O pin and get a little shorter (and faster) > PIC code. > > One problem with "reading" the original audio signal, > is that you *could* be doing the ADC-conversion right > when the level is low enought to give a false "no-audio" > answer. So you probably whant to have some signal > smothing (integration) circuit anyway. This depends > on what reaction times you expect. > Best Regards, > Jan-Erik. > > > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist -- = http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist