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31  Using Arduino / General Electronics / Re: Basic Capacitor Question on: September 04, 2012, 01:59:16 pm
Surely the direction of the current flow will depend on whether the capacitor is being charged or discharged at that moment ?. If its a static voltage there won't shouldn't be any current flowing at all. 
32  Using Arduino / General Electronics / Re: Problem powering a toy car engine with Arduino Mega 2560 on: September 01, 2012, 04:09:53 pm
Yes the 5V pin will supply much more current than a digital pin.  Your toy car motor will draw far more current than an arduino digital pin will supply.  I don't know how you are measuring current but the figures are a long way from what a typical motor will draw.  I have a tiny vibrator motor from a mobile phone ( physically smaller the the nail on your pinky ) it draws more current than an arduino pin can supply (around 60 mA). A toy car motor will use at least several hundred mA and possibly more than that.  Typically you'll use a transistor to drive a small motor from an arduino pin
33  Using Arduino / Installation & Troubleshooting / Re: Serial monitor speed selection problem on: August 22, 2012, 05:11:41 am
I use Ubuntu 12.04 (32 bit) with version 1.0.1 of the IDE.  It works fine with both my old Duemilanoves and my first generation Uno at 38400. The Uno has had the 8U2 firmware updated though.  The early firmware had known serial issues with Linux
34  Using Arduino / Installation & Troubleshooting / Re: Arduino will not run on Linux on: August 21, 2012, 03:40:12 pm
The dialout group causes problems with communicating with the Arduino, the OP hasn't got that far, the software won't start in the first place.  You get the classic greyed out Serial box in the IDE if you don't have permissions to use the Serial ports. I never needed to bother with it with 10.04 Ubuntu but I needed it with 12.04.
35  Using Arduino / Installation & Troubleshooting / Re: Arduino will not run on Linux on: August 21, 2012, 01:58:29 pm
Instead of running the arduino ide by double clicking it, run it from terminal. That will give some clues as to what is wrong.

in terminal, cd to the directory where the arduino program resides

in mine this is ~/arduino-1.0.1
cd ~/arduino-1.0.1

run the program using


Posting what it says in the terminal window will be a big help.
36  Using Arduino / Installation & Troubleshooting / Re: Arduino will not run on Linux on: August 21, 2012, 10:38:55 am
Where did you extract the software to ?

If you use terminal to start the IDE by hand, what does it report ?  The GUI tends to hide a lot of messages that are useful to debugging.
37  Community / Bar Sport / Re: Raspberry Pi launch farce on: August 18, 2012, 11:57:12 am
Don't judge linux by your experience with the Pi, GM.  Besides the realtime issue, which isn't really an issue once you accept its a multitasking OS (although putting GPIO on it lends itself to needing realtime), Linux on the Pi and Linux on half decent hardware are two entirely unrelated animals.  I use it full time, although my distro of choice is Ubuntu, Debian is close enough so the differences on the Pi aren't great. The Pi sucks because of the severe compromises made to get the price down in my opinion.  You're right, it is stone soup.  The choice of power supply is the root of a lot of the problems.  Charging a smart phone battery is a whole different animal to running a desktop computer, factor in the polyfuses (needed to stop it overloading said PSU and wiring) and the poor USB/ethernet implementation and the whole thing becomes a pain.  Its lack of grunt is sometimes a problem but I'll leave that bit alone.

I have now a rock solid Pi, (attacking said polyfuses with a soldering iron and feeding it power via the GPIO pins got rid of many of the problems I was having) , but I still can't get it to play nicely with any of my webcams (all of which are plug and play on my PC and Ubuntu) and using workarounds for talking to an Arduino is a pain.  I've just ordered a 'works out of the box' webcam as a last ditch attempt to get it to do what I want, we'll see on that front.

I'd take Linux over OSX anyday but I haven't really used a Mac in earnest since Tiger. 

38  Community / Bar Sport / Re: Not TRYING to start a flame war honest. on: August 16, 2012, 03:35:16 am
Ah, Pascal, My first real programming language..........  smiley

BASIC doesn't cut it as a 'real' language.
39  Using Arduino / Programming Questions / Re: need help on liquid crystal library on: August 13, 2012, 02:05:17 am
 All recent versions (from about 0014 onwards if memory serves) have the liquid crystal library as standard.  Its very likely its an old library that hasn't been updated to work with the newer versions of the IDE. Do you need the extra functionality ? (the shift register bit), if not, I'd just use the built in one.
40  Using Arduino / Installation & Troubleshooting / Re: Upload from Linux Ubuntu Stopped Working on: July 27, 2012, 02:17:43 pm
There is/was a known issue with early Uno boards where the DFU firmware caused a problem with linux systems if a sketch using serial had been uploaded.  It was sorted over a year ago but if you have an old board or its a clone still using outdated firmware it may be the issue.,52908.0.html
41  Community / Bar Sport / Re: Raspberry Pi launch farce on: July 26, 2012, 07:48:20 am
With workarounds I've got my earlier one doing part of what I envisaged it doing (webserver with far less limitations than an arduino with ethernet shield basically).  Too many fudges with all they had to do to make it as cheap as it is.  Its hopeless as a desktop replacement.  With my limited expectations of the platform, I'm battling with the poor USB / ethernet implementation (along with half those posting on the Pi forum it seems).   


Its one I came across on another of my haunts :   , I 'borrowed' it. I love it as well.
42  Community / Bar Sport / Re: Raspberry Pi launch farce on: July 26, 2012, 04:52:57 am
I'll just park a copy of this here for safekeeping :

by pluggy ยป Thu Jul 26, 2012 10:31 am
I complained about RS a while back and had the thread deleted for my trouble. They've had my money for a month with a delivery date in October. Ring up and they fob you off with "you have to email the Raspberry Pi team", needless to say I'm still waiting for a reply 3 weeks later. No doubt this thread will be going the way of the Dodo bird as well. Their justification being if you read the sticky at the top it says:

It is not the place to air general moans or complaints about RS or Farnell (or anyone else for that matter)

Since its pretty obvious RS don't give a ****, the foundations unholy alliance with said company is next in line. Already had one warning, no doubt I'll be down the road after this.

If they can't fulfil the order in a reasonable time frame, they have no justification whatever for taking your money when you place the order.

Dear Mod, I didn't start this thread, another disgruntled RS customer did, Since the foundation formed the alliance with them, the foundation have a responsibility. Of course, you can take a leaf out of RS's book and hide behind your terms and conditions..........

It is/was here :

All rumours to the effect that the Ras Pi mods are heavy handed is totally unfounded......    
43  Using Arduino / Project Guidance / Re: What were they thinking? on: July 22, 2012, 10:28:20 am
Yep, its an officially a 'brain fart' . If it worries you too much, theres nice Seeeduino boards that have the option of putting a second row of headers in at standard spacing so your home brew stripboard shield fits without a lot of messing around. 
44  Using Arduino / Installation & Troubleshooting / Re: usb cord for uno on: July 22, 2012, 10:03:11 am
In the old days, these cables used to be used for USB printers, but I think the printer industry has moved on to newer cables.  You might check if you have older printers, and such whether you already have the cable or not.

This industry moves on far too quickly without you wishing it away as well. The USB A-B lead is still almost universal for printers. New fangled ones are often wireless as well but often need the USB for setting up the wireless in the first place (or squinting at a tiny display and working through endless menus) . Some low end Multifunction wireless devices are only wireless as printers and need a USB cable to use the scanner part.   Network printers often have ethernet as well as USB, but the USB A-B is still the cable of choice for printers. More often than not, NOT included with the printer so the store can charge you some exorbitant fee on top of the printer.  Available for very little on Ebay.  

Many other devices have moved on to Mini and Micro USB but as a printer can't really shrink very much, there's little point in shrinking the USB connection.

Its only fairly recently the industry has abandoned the old Centronics parallel connector altogether.  The computer manufacturers kept it on so if you still had a really old printer.....
45  Community / Bar Sport / Re: Raspberry Pi launch farce on: July 21, 2012, 02:00:04 pm
Here you go GM, a Pi with real interrupts :

Whadaya mean, sticking an Atmega 328 on top is cheating ?  smiley-wink

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