If you need a way to allow access to a motor vehicle without using the keys (for example to allow children to retrieve their belongings, without messing around the with radio etc) then the following project by Stephen Newberry solves the problem nicely. Stephen has documented how to add an Arduino-controlled numeric keypad that can activate the central locking and thus let the user open the doors.
The key (!) to a successful system is locating the circuit in the vehicle that activates the central locking, and the rest is quite simple thanks to the ease of working with an Arduino. Finally, a quick demosntration is shown in the following video:
For those interested in reproducing this, Stephen has made the schematic and sketch available on Google Docs. And for more, we're on facebook, twitter and Google+, so follow us for news and product updates as well.
If you're looking to learn how to use an Arduino with numeric keypads and much more, you can't go past reading a copy of "Arduino Workshop - A Hands-On Introduction with 65 Projects” by John Boxall.
Arduino Workshop takes the reader from having zero knowledge about the Arduino platform, electronics and programming and leaves them with the know-how and instructions on everything from blinking an LED, to robotics, wireless data, cellular communications, motor control, sensors, Internet connected systems and more. For more information including a sample chapter and table of contents, visit the book page.