Raspberry Pi 2 Model B Switches/Door Contact Switches

Question

Hi,

I am new to the Raspberry Pi and I was wondering how I would connect door contact switches (or any kind of switch) to the pins on my Raspberry Pi. I have a Raspberry Pi 2, Model B. The purpose of this so that I could read if the door switches are together, and thus and are sending a voltage through the door switches, and I am aiming to somehow have the Raspberry Pi detect if this voltage has reached it, on one of its pins. Does anyone have an idea of how I could use this door switches, or any switches, on the Raspberry Pi? I am a beginner in breadboarding and wiring, and I am wondering how exactly I could measure whether or not these door switches are in contact. Please ask if you need more information.

Thank you for your help.

Robert Peter Oakes · Accepted Answer

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

Former Member · Answer

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.

Former Member · Answer

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,