Articles

An Associative Container for non-bash Shell Scripts

Wednesday, 2 Feb 2022 - 20:04 +0000 by Ralph McArdell code, Bash, shell script

Introduction Have you ever found yourself stuck with having to write a *nix / *nux shell script that cannot assume that Bash and system core utilites having GNU extensions are available and so specify the shell processor simply to be /bin/sh and then found you could really use some sort of container to store multiple values? This happened to me a while ago and I thought I would attempt to create an associative container abstraction that could be used with only basic shell facilities.

C++11 (and beyond) Exception Support

Wednesday, 27 Sep 2017 - 16:26 +0100 by Ralph McArdell code, C++

Introduction C++11 added a raft of new features to the C++ standard library and errors and exceptions were not left out. In this article we will start with a quick overview of the new exception types and exception related features. While the nitty gritty details are not covered in great depth in most cases a simple usage example will be provided. The information was pulled together from various sources[1][2][3], and these, along with others, can be used to look up the in depth, detailed, specifics.

Raspberry Pi Linux User Mode GPIO in C++ - Part 3

Wednesday, 30 Sep 2015 - 12:33 +0100 by Ralph McArdell Raspberry Pi, Linux, code, C++, GPIO

The previous instalments[1][2] have described creating the rpi-peripherals[3] library to access general purpose input output (GPIO) on a Raspberry Pi running Raspbian Linux in C++ from user space. They covered creating the phymem_ptr class template that utilises RAII (resource acquisition is initialisation[4]) to manage mapped areas of physical memory, setting up the library project and the implementation of support for basic general purpose input and output of single bit Boolean values, clocks and pulse with modulation (PWM).

Raspberry Pi Linux User Mode GPIO in C++ - Part 2

Wednesday, 29 Jul 2015 - 18:04 +0100 by Ralph McArdell Raspberry Pi, Linux, code, C++, GPIO

Previously[1] I described the initial stage of developing a library called rpi-peripherals[2] to access general purpose input output (GPIO) on a Raspberry Pi running Raspbian Linux in C++ from user land – that is there are no kernel mode parts to the library. The library was built on memory mapping the physical memory locations of the Raspberry Pi’s BCM2835 processor’s peripherals’ control registers using the dev/mem device accessed via a RAII (resource acquisition is initialisation[3]) resource managing class template called phymem_ptr.

Raspberry Pi Linux User Mode GPIO in C++ - Part 1

Thursday, 26 Mar 2015 - 15:22 +0100 by Ralph McArdell Raspberry Pi, Linux, code, C++, GPIO, mmap

I started experimenting with Raspberry Pi GPIO using Python[1][2]. Then the original Gertboard[3] kit was released so I ordered and built one which enabled me to play with BCM2835 peripheral IO beyond basic GPIO. At the time the Gertboard had test and example C code available[4] that, as with the Python case, I felt could be expressed more cleanly. I thought it would be interesting to see what advantages C++, hopefully C++11, features and idioms might provide.

Raspberry Pi Linux User Mode GPIO in Python

Saturday, 18 May 2013 - 14:28 +0100 by Ralph McArdell Raspberry Pi, Linux, code, Python, GPIO, sys filesystem

In this article I am going to discuss an alternative approach to using GPIO on a Raspberry Pi in Python to that taken by an early version the RPi.GPIO package[1]. The approach occurred to me in 2012 while making a start at hardware interfacing and programming using a Raspberry Pi with some LEDs, switches and the like that had been collecting dust for 20 to 30 years. To read and write data to the GPIO lines I thought I would start with Python and the RPi.