Ok, I'll wrap a few replies into this email. Andrew, thanks for the interesting debouncing suggestion. I was hoping to use the CCP module, so I'm not sure software debouncing will work. I'll have to check into this though, I haven't studied up on the CCP module in awhile. Dave, thanks for the advice about the Behringer stuff. Jinx, good suggestion on the alternative switching methods. I'm not sure I'd be able to get a hall effect or opto setup to "feel" right though. How about a piezo disc with a rubber pad on top that can be tapped? I might run into problems with levels though, what if one person hits it hard while another hits it soft? I also need to sit down and do the math for the fastest BPM I want to be able to measure, then how much time to allow for switch bounce, and if I can use an RC or something similar. Perhaps a mechanical switch will work (provided the math works). We'll see. I figure that if I can get a manual version working, I can then start playing with filters and measuring the audio directly. Ok, much to think about...thanks all! Josh -- A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools. -Douglas Adams On Fri, 24 Dec 2004 10:24:45 +1300, Jinx wrote: > > It's not ideal when DJing as you'd need to re-tap as you adjust > > the speed of the music. Also, getting down to 0.1 beat accuracy > > might be a bit harder > > Is this for mostly Drum'n'Bass / Techno type music ? That should > be pretty easy to filter down to a beat. If this was for personal use > I think I'd characterise the track beforehand with a particular filter. > With two BPM units you could synchronise the two tracks. Then > you'd not have to worry about the absolute value of the count. > > > Any ideas on debouncing a switch? I can't have too much lag > > on it (ie a large RC) or it'll skew the BPM measurement...right? > > For something long-lasting and bounce-free I'd look at either > a magnet and Schmitt trigger Hall switch or a blade and opto- > interrupter. Anything that doesn't have mechanical contacts -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist