Python Code for 3×4 Matrix Keypad with Raspberry Pi #piday #raspberrypi @Raspberry_Pi


Chris Crumpacker writes:

Another module of my alarm interface is done. I picked up a 3×4 matrix keypad from Adafruit (http://www.adafruit.com/products/419) But couldn’t find any good python code examples for it’s use. I was able to find a few examples that lead me down the right path in terms of scanning rows first as inputs and then swaping pins to scan the columns. I wrote two libraries, the first just uses 7 of the Raspberry Pi’s GPIO pins then I also wrote one that works for the MCP23008 chip since I’m really in a mode of saving pins when I can 🙂 Then also just wrote a demo script to show calling the libraries and their use.

Here is the code as it stands now, I have some ideas on how to change it to be better but this is fully working for now.

Check out the blog post with source code here!

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Membrane 3×4 Matrix Keypad + extras – 3×4 – Punch in your secret key into this numeric matrix keypad. This keypad has 12 buttons, arranged in a telephone-line 3×4 grid. It’s made of a thin, flexible membrane material with an adhesive backing (just remove the paper) so you can attach it to nearly anything. (read more)

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