--- Original Message --- From: "Michael Cunningham" To: Cc: Sent: Fri, 17 Dec 2004 00:57:14 -0500 Subject: audio servo driver PIC design help :: I breadboarded the design ya'll helped me :: :: with previously and everything works perfectly! :: Thankyou!.. Now on to my next challenge.. it is :: stretching my mental capacities so far and should give :: me experience with the a/d converter if it can work :: like I think it might. This is a hobby circuit.. nothing :: professional here. :: :: I have a servo mounted in a fake skull that can move :: the skull's jaw. There are several non PIC based circuits out there :: now to do this but they are simple threshold circuits. :: If the circuit detects an audio signal it tells the servo :: to move as rapidly as possible to open the jaw until sound :: is not detected and it closes the jaw as rapidly as possible. :: While this works..its not very realistic. Its doesn't account :: for the fact that a loud sound should open the jaw faster :: and in turn, further then a softer sound. :: :: It seems that a PIC with an a/d converter and ability to drive a :: servo using PWM could be a good solution to this. :: :: Basically what I want to do is sample a line level audio :: signal pretty rapidly and based on the presence of sound :: move the servo to open the jaw at a rate based on the :: amplitude of the sound, so a louder sound will cause the servo :: to move quicker to a location and hence further then a :: softer sound which will cause the servo to move slower and less :: distance then the louder sound. So if it screams it will rapidly :: move the jaw open, and a whisper will just cause a tiny jaw :: movement :: despite the duration of the sound. :: :: After doing some basic research on the net it looks like I will :: need to use some circuitry to cleanup the audio signal since :: the a/d converter bases its comparisons on 0 to Vdd and as I :: understand it, audio signals aren't 0 to 5 volts. :: :: Any ideas how I can do what I want to do? I know this project :: is probably over my skill level, but ya don't learn unless you :: push yourself. How would you do it? I don't think the actual :: circuit is the big issue (except for the audio cleanup part - no :: clue there) since there are plenty of examples of driving servos :: with PICS on the net. My biggest hurdle is using the a/d converter :: to figure out if sound is present and the amplitude of it and :: creating a direction and rate at which to move the servo. :: :: Thanks, :: Mike :: :: :: _______________________________________________ :: http://www.piclist.com PIC/SX FAQ & list archive :: View/change your membership options at :: http://mailman.mit.edu/mailman/listinfo/piclist -- cdb, cdb@barnard.name on Friday,17 December,2004 Web presence: www.btech-online.co.uk Hosted by: www.1and1.co.uk/?k_id=7988359 Light travels faster than sound. That's why some people appear bright until they speak! _______________________________________________ http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist