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BSD Unix related content

Simulating GPIO Pins

Gespeichert von Marc Balmer am Do., 01/03/2008 - 17:35

I am currently writing a control and monitoring software system that makes use of GPIO pins. Since I was at the CCC congress in Berlin I did only have my laptop and no real GPIO hardware... With only a laptop it's a bit hard to write GPIO software, since laptops usually don't have any GPIO pins. So what I needed to test my new software was either a real device (out of reach) or... writing a simulator.

<Nick> What is a GPIO Simulator? <kettenis> You write to a pin and nothing happens...

Decoding the DCF77 and HBG Time Signal Stations Using OpenBSD

Gespeichert von Marc Balmer am Sa., 12/22/2007 - 12:19

Marc Balmer , The OpenBSD Project Copyright (C) 2006 Marc Balmer Every computer is equipped with at least a clock chip or a general purpose device to provide a timer function. While these timers are certainly precise enough for measuring relatively short periods of time, they are not well suited for keeping the correct time and date over a longer period, since almost every chip drifts by a few seconds per day. Even so called real-time clocks only approximately meet the real time. Time signal stations can be a solution to this problem as they emit very precise time information using specifically modulated radio frequencies. Time signal stations are available in many countries; while the coding schemes vary from time signal station to time signal station, the decoding principles are similar.

Using OpenBSD's chrooted httpd

Gespeichert von Marc Balmer am Sa., 12/22/2007 - 11:52

Copyright © 2003-2008 by Marc Balmer. All rights reserved. OpenBSD some time ago changed the mode of operation for the Apache webserver from the normal non-chrooted operation to chrooted operation. This enhances the security of the server on which Apache is run but it imposes a few challenges to the system administrator. In this article I will discuss selected aspects of running a chrooted HTTP daemon and present strategies on how to set up a chrooted environment for more complex applications like database access or using CGI-scripts. (First published on April 6, 2003, revised on March 20, 2004, converted to HTML for online publishing on December 21, 2007.)