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.
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)
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.