Where is all this noise coming from?
March 2, 2009
I am finally getting around to Walter's autonomous drive mode and have run into a noise issue. It seems that my motor driver (this one) is affecting my sharp IR sensors. I am still running the motor driver off of a 14.4V DeWalt drill battery as I can't afford proper batteries yet (I don't know if that makes a difference). The Picaxe 40x1 is powered by 5 AA's with a 7805 regulator (included with the regulator is a 220uf+ cap, a 10uf+ cap and a 100nf ceramic cap in a regular configuration). Of course, the regulator and motor driver share a ground. It seems, with the motor battery disconected, my sharps are a-ok spitting out a value of about 10 or so with nothing in front. However, when the motor battery is plugged in, they jump up to about 50 or 60 (on average) while fluxuating as high as 80 and as low as 1 in short bursts. Even more odd, when the motor driver battery starts going dead, the problem seems to be resolved. Is there a way to isolate the motor driver or can I get rid of this noise another way? Big caps somewhere, maybe?