Raspberry Pi 2 Model B Switches/Door Contact Switches

Jack, adding switches/buttons to the Pi is easy, but not without some "gotchas".  If you haven't downloaded the past issues of The MagPi magazine I encourage you to do so since this very topic is covered in several issues.  I teach classes on the Pi at the science museum I work for and this what some of the students will be tackling in a few weeks.

I'm sure others will chime in here, but if you have some very specific questions, or a more detailed description of what you're trying to do, feel free to contact me directly at: bgrawburg  'at' imaginescience  'dot'  org.

Good luck,

Hi Brian, thanks a lot for your help. I will try your suggestion!

Rather than connect direct to the PI, I would use an interface board to provide some level of protection in case of minor errors.

The PI can be used by connecting switches directly of course and this is done all the time in prototypes etc or for a learning excersize

The simples thing I can think of to help would be the PIFace Digital, this provides 8 Digital inputs via a buffer chip and 8 digital outputs (Two of which drive relays), the board is well suppported in the community and by the vendor

here is a link to the canada Newark site http://canada.newark.com/piface/piface-digital-2/io-expansion-board-raspberry-pi/dp/78X5847?mckv=saxFsj780|pcrid|40869928673|plid|&CMP=KNC-GCA-GEN-SKU-PIFACE?gross_price=

Prices will vary from region to region but this is a very popular board to extend the PI

here is more info http://www.element14.com/community/docs/DOC-69001/l/piface-digital-2-for-raspberry-pi

Depending upon how many I/O pins I need I use either an MCP23008 or MCP23017 port expander.  I have an article in the Dec 2014 issue of The MagPi magazine about using two MCP23017s. I also made a PCB for a single MCP23008 that makes hooking up to the Pi easy.  The PiFace includes more than I usually need for a project; it does have the advantage of being able to do lots of things with s single board, however.

Ok thanks, that will help me with my project!

if you would not mind, can you check the "Correct Answer" or "Helpful Answer" for me then, I need the badge

Peter Oakes great answer and I would mark correct as well (if I could). Thanks for the excellent explanation.

Clem

Sure, no problem!