Archive for the ‘Technical’ Category

Linux

March 11, 2011

I have a real enthusiasm for Linux, the freedom, the open source, and the zero cost. There is so much that commends Linux to be used, to be loved and to be acclaimed.

Linux penguin logo

Linux Penguin

When I was given a PC the other day with a 2GHz processor which happens to be faster than all my existing PCs, and initial assessment proved it to be unsuitable to directly replace anything I currently had (it was not a laptop and did not have hardware RAID), I thought that it might actually be a bit more useful if I put Linux on it.

The processor should be fast enough (I have run Red Hat on a pentium 90 before) and 2GB of memory should be handy too. So, not being one to change unless it was necessary I downloaded the latest Fedora KDE ISO and had a go.

Fedora core 14 logoUnfortunately the reality of using Linux is that it is not quite as straightforward as it should be. The basic install is all very straightforward, once I had found a hard disk that had not been previously used in a RAID array to use as the boot disk. The setup program felt the need to identify the former RAID disks as software RAID disks and could not find them to boot on.

A 6GB disk should have been big enough, but Druid did not think so. It insisted on telling me it was not big enough and that I should replace it with one bigger than 2GB – no useful message as to why, no option to look at how it was trying to partition it, no option to edit its suggested partioning – just the option of doing my own partitioning from scratch – with no meaningful information provided as to what partitions were required.

Ok, so I had a guess. 5GB should be enough for the OS, 500MB for swap, and leave the rest to play with later. Should not be too hard to make adjustments later, Disk Druid looks like a handy utility that should be easy to use, that is if it is available – which it is not of course. It is an install time only utility. A couple of hours research on a Windows PC managed to turn up how to configure the swap partition manually.

The rest of the install plods along nicely, and there I have it, a nice Fedora 14 PC for free.

I try a few things out and find out the sound is not working. Change the BIOS setting from AUTO to ENABLED and it springs to life, not too much of a problem.

Using the built in utilities and applications is fine. They appear to work OK and do what they are supposed to. I can even do a bit of web browsing on Konquerer. That is handy because now I can get on the internet and download some useful applications.

Previous attempts at working with Linux had been rather stifled because all the instructions for doing anything expected that you had an online connection to the internet, not just the ability to download elsewhere, burn to a CD and install from that. The coming of ADSL has been jolly handy.

I say all the instructions, but for some reason, and this appears to be peculiar to Linux, any attempt at doing anything other than very basic things are always met with the statement “If you need to ask how to do this you are too stupid to be doing it” or words to that effect. This is mainly found around trying to install drivers or something that needs you to recompile the core. Very frustrating and not really in the spirit of open source. Why should an IT professional be too stupid to understand how to recompile the core?

So, I fancy using Firefox as my browser. Konquerer might be OK, but I know how to use Firefox. Go to the Firefox website, download it, click on the downloaded file, and we are away. Firefox installs and runs, all the familiar stuff – excellent. Close Firefox.Firefox

Next day, switch on Linux PC, log in, fine. I would like to do some browsing. Konquerer is there in the start menu, but where is Firefox? It isn’t there. It is not exactly rocket science to add a shortcut I wouldn’t have thought, but still, this is Linux – not for ordinary people.

A quick search in Dolphin and there is Firefox. Hmmm. Perhaps I can make a link to it myself. What runs it, ah, this shell script seems to do it. Click the shell script and Firefox fires up. Excellent.

Drag the shell script to the desktop, choose make link. Click the link and see the shell script open for editing. Not quite what I was expecting and not very useful. Ah well, at least I can launch Firefox now if I need it by finding it in Dolphin. Konquerer will probably be OK most of the time.

Ahh. Google Chrome is available for Linux too. Why not give that a try. Shock Horror, it installs and puts a shortcut in next to Konquerer. So it can be done.

I am on a roll now. Openoffice.org here I come. this surely will install OK. It has a big organisation behind it so will be designed for easy install.

No. That would be silly. People might use it. I download the archive, and unzip it. Lots of RPMs to install now. None of them are signed so I have to give root authentication twice for each one. An hour later with the forty or so individual packages installed, it is time to try it.

I will try it one day when I find out what you are supposed to run to use it! No shortcuts in the applications menu (or none that I can find anyway).

As an open source developer myself, who always strives to the highest standard of documentation to ensure that what I produce is fully usable, and usable by anyone, I am appalled at what is produced for Linux. I am sure that the underlying code is pretty good, but there does not appear to be very much testing of either the product or the documentation. Google appear to know what they are doing but that is about as far as it goes.

OK, so I don’t like what I see.

“Do something about it yourself then!” I hear chorused.

err, no. I do my own development for the open source community, and it is a community. We all do our own bit and the result is there for all to use. I do not expect everyone who uses my code to contribute code as well. Not everyone can code but everyone can contribute to society That is good enough for me.

Open source is not about second rate, is not about being ‘Geeky’, it is about contributing to society for the greater good. Professionalism has the same place in the open source community as elsewhere and there is no reason that Linux can not become first rate, but it has to be taken seriously, especially by the developers.

Suzie x

Designing for cool

July 14, 2010

I have not posted any little technical tips lately, so here is a tip to make your micro-controller based projects suitable for the cool shelf and not the nerdy shelf.

Just as low voltage micro-controllers appeared that can be run on a 3V power supply which is easily attainable from a couple of AA batteries, so appeared blue and white LEDs at affordable prices, with their inherent forward voltage of more than 3V.

Blue LED tyre light on a car wheel

Cool gadget

Society has now decided that white LEDs are cool, blue LEDs are super cool, and violet LEDs are really mega cool. It has become very easy to visually identify how cool your gadget is by what colour it lights up when you turn it on. Clearly anything that has an orange, yellow, green, or dare I suggest red LED is just old fashioned and nerdy.

Designer clock with red light emitting diode display

Less cool gadget

This has resulted in a design choice with not always the coolest outcome. Your choices are:-

– You can increase the supply voltage by adding an extra couple of AA cells, probably making it a bit heavier, but getting enough voltage for a cool coloured LED.

– You can use an unfashionable coloured LED.

– You can play the green card and not use an indicator at all.

Here is an alternative, a way to run your voltage hungry cool coloured LED from 3V using little more than software and ten pennies worth of components:-

Circuit diagram showing how to connect a blue LED to a three volt microcontroller

How to drive a blue led from a three volt micro-controller

All you need to do is provide an anti-phase square wave output on the two port pins. This can be done as an interrupt routine or as part of a polling routine in software quite easily.

With careful selection of which pins you use you may even be able to use an on board peripheral like a PWM generator or timer to generate the signal.

Careful selection of the capacitor values and adjustment of the mark/space ratio of the output square wave will allow you to adjust the brightness of the LED in software for added kudos to take you up another level on the cool shelf.

Suzie x

Stripboard CAD

April 3, 2008

Laying out prototype circuits on stripboard and then documenting them is not easy to do efficiently, even with twenty five years of practice, so it is handy to find a bit of free software to do it for you.

Stripboard designer is a simple program that makes pretty documentation of your layout but does not help with the design:-

http://www.geocities.com/stripboarddesigner/

TinyCAD combined with VeeCAD can take you all the way from schematic capture to the layout of your veroboard:-

http://tinycad.sourceforge.net/index.html

http://veecad.com/

Suzie x

p.s. Since I made this post some things have changed like the demise of Geocities. Here is a link to a new app that works (today anyway!):-

Reprap Stripoard designer