
James decided to reverse engineer car ultrasonic parking sensors. These sensors have integrated electronics that handle all the measurements. They are connected to the car’s internal computer via a low-speed single wire CAN network. James provides pinouts, protocol interface, and some source code to interface with them.
Since I know a thing, or two, about ultrasonic sensors and systems, I thought I would give back to the community with some insights. There are many millions of ultrasonic sensors produced each year for the vehicle manufactures. To date, I don’t see any of these sensors getting reused by the hacker community. I’m guessing this is simply due to a lack of understanding of these sensors. The automotive ultrasonic sensors would make great hobbyist’s sensors. The sensors are almost indestructible as compared to the hobbyist sensors I see used today. Below are a couple of advantages of the automotive ultrasonic sensors.
Via the forum

Have you done any work with the now incredibly cheap backup sensors? I’ve bought a few from China ($1.50 apiece) And was wondering if you knew any specs or, perhaps how to interface these with a “standard” duino or beagle like critter…
The Jame’s link doesn’t work.