Python, Linux, and Lionel trains
In Control
Controlling a miniature train empire with concurrent Linux processes.
Two hobbies are prevalent in my house: Lionel trains and Linux computers. The train layout isn’t a permanent fixture; it gets set up a couple of times a year – usually around Christmas – but it’s been known to appear during the summer as well. The last time it appeared, I added a Linux computer to control the setup. Although I still run the trains with traditional throttles, I let the computer play with the rest.
Rather than write one massive control program, I decided to split the design into single-purpose modules that run independently (Figure 1). Each module performs a single task in either the input, output, or control categories. Any given input or output module corresponds directly to a specific piece of hardware. Control modules don’t have hardware equivalents but instead provide the logic that links the inputs and outputs. Any number of modules can be run simultaneously.
The modules are written in Python and use mmap to communicate among themselves. The files inputs.txt, which represents the current state of the railroad’s sensors, and outputs.txt, which has the requested state for the relays or LEDs that activate working accessories, are memory-mapped files. They are both initialized to a single line of 100 zeros.
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you've found an article to be beneficial.
News
-
Fedora 39 Beta is Now Available for Testing
For fans and users of Fedora Linux, the first beta of release 39 is now available, which is a minor upgrade but does include GNOME 45.
-
Fedora Linux 40 to Drop X11 for KDE Plasma
When Fedora 40 arrives in 2024, there will be a few big changes coming, especially for the KDE Plasma option.
-
Real-Time Ubuntu Available in AWS Marketplace
Anyone looking for a Linux distribution for real-time processing could do a whole lot worse than Real-Time Ubuntu.
-
KSMBD Finally Reaches a Stable State
For those who've been looking forward to the first release of KSMBD, after two years it's no longer considered experimental.
-
Nitrux 3.0.0 Has Been Released
The latest version of Nitrux brings plenty of innovation and fresh apps to the table.
-
Linux From Scratch 12.0 Now Available
If you're looking to roll your own Linux distribution, the latest version of Linux From Scratch is now available with plenty of updates.
-
Linux Kernel 6.5 Has Been Released
The newest Linux kernel, version 6.5, now includes initial support for two very exciting features.
-
UbuntuDDE 23.04 Now Available
A new version of the UbuntuDDE remix has finally arrived with all the updates from the Deepin desktop and everything that comes with the Ubuntu 23.04 base.
-
Star Labs Reveals a New Surface-Like Linux Tablet
If you've ever wanted a tablet that rivals the MS Surface, you're in luck as Star Labs has created such a device.
-
SUSE Going Private (Again)
The company behind SUSE Linux Enterprise, Rancher, and NeuVector recently announced that Marcel LUX III SARL (Marcel), its majority shareholder, intends to delist it from the Frankfurt Stock Exchange by way of a merger.