A dog owner has used his Raspberry Pi to build a noise-sensing circuit that opens the door for the canine when it barks.
Dave Hunt’s project was posted on the Raspberry Pi website, with Hunt saying that the barking of his new dog to be let in and out drove him to design the Pi-Rex.
For those who wish to create their own Pi-Rex doggy-door, Hunt has posted expansive instructions and details on his website. The meat of the circuit is a noise detector adjusted to respond to barking noises which fires a door-unlocking motor when the sounds are detected.
Hunt, who lives in Limerick, says he picked up the necessary audio detection circuit in high-street store Maplin for €9.99, and that construction took a swift half-an-hour.
While the door currently only opens, Hunt specifies that the invention is only a proof of concept, not a security fashion.

http://www.pcr-online.biz/news/read/...-pi-rex/031695