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Posts Tagged ‘GPIO’

Any m-by-n Matrix Keypad for Raspberry Pi

In ARM Linux, Coding on 9 February 2014 with no comments 424 views

What about instantiating any m x n matrix keypad by a Python class? Raspberry Pi takes me to learn how to build a Python class for the first time while expanding my initial WiringPi-based matrix keypad into a derivative work. A matrix keypad instance is defined by: Actual GPIO pins used forming the row and [...]

Raspberry Pi: Membrane (Matrix) Keypad as GPIO Input

In ARM Linux on 13 March 2013 with Comments Off 4549 views

Membrane matrix keypad using GPIO as Raspberry Pi input has been my goal since WiringPi deployed in the first place. To begin with, GPIO hacking was initially started with some important basics (see previous post). Without external system (other interfacing chip), the 3×4 membrane keypad reserved all seven GPIO pins plus one pin used for [...]

Raspberry Pi GPIO Input Button Basics

In ARM Linux on 11 March 2013 with no comments 2654 views

When you start hacking Raspberry Pi’s GPIO, first thing to keep in mind is the +3.3V CMOS logic level voltage despite the 5V supply. Secondly, read references about current limiting resistors (eLinux Wiki has a section there). What to avoid then? Try not to physically short the GPIO pin to ground when it is programmed [...]