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1  Using Arduino / General Electronics / Re: Aproaching definitive PCB on: September 22, 2012, 06:05:18 pm
I would try without using the autorouter - it seems like it will be hard or it will take a long time, but its worth it.

I find that doing the power first helps, and if I have the top layer for mostly going horizontal and the bottom layer vertical things get a bit easier. You could of course swap those around.

This might help you condense your board into a smaller area so you can get it into one of seeed studio's 10cmx10cm board pricing ranges - which is a lot cheaper than their 15cmx15cm price!

One things am doing at the moment is splitting up component parts of a circuit over two boards to fit into the 100x80mm board size restriction in Eagle, then connecting the relevant parts and power with a double row pin header.

One last thing, and its not important but it bugs me, odd angle traces look ugly.
2  Using Arduino / LEDs and Multiplexing / Re: Need URGENT help with IC alternatives on: September 18, 2012, 01:44:20 pm
You might find this video by Jeri Ellsworth helpful.



Have you thought about using a voltage divider if you're going from 5v to 3v3 in one direction?
3  Community / Exhibition / Gallery / Re: Portable console on: August 19, 2012, 05:44:57 am
Both of those look really good. The Conway's GOL especially, the elements on the screen are complex and great to look at!
4  Using Arduino / Interfacing w/ Software on the Computer / Re: Interfacing to a Tablet or Pad on: August 15, 2012, 11:16:11 am
For android tablets, look into amarino

http://www.amarino-toolkit.net/

And the android accessory kit from google

http://arduino.cc/blog/2012/06/28/android-adk2012-is-here/

I would imagine that interfacing with the iPad would be more difficult because it is so locked down, but you can get an apple connector broken out so you can solder pins to it. There's also an app that works with the Ethernet shield I think, it shows the controls/display the arduino tells it to
5  Using Arduino / General Electronics / Re: min voltage a atmega 328 will operate at? on: July 29, 2012, 08:46:04 am
http://www.atmel.com/Images/8271s.pdf

At the bottom of the datasheet's front page, 1.8v.
Maximum reliable clock speed is 4MHz at that voltage.
6  Using Arduino / Motors, Mechanics, and Power / Re: Precise positioning of a servo on: June 25, 2012, 11:58:22 am
You might want to look into motorised potentiometers, they sound ideal for what you want.

Other than that, setting a specific post tion is pretty much what servos are for...
7  Using Arduino / Programming Questions / Re: how do I minimize ADC clock freq via a register? on: April 23, 2012, 02:24:39 pm
The ADPSn bits are part of the ADCSRA register. You can set them using code like the following -

Code:
// ADC clock prescaler 8
ADCSRA |= (1 << ADPS1) | (1 << ADPS0);

That's untested but it should work. The exact combination of bits that you turn on affects the pre scaler, but you know that already from reading the data sheet smiley

Look up bit wise operations/bitmath for more information about what is going on, or search for something like "AVR set bit"
8  Using Arduino / Programming Questions / Re: Invalid device signature for ATtiny84 SOIC package on: April 23, 2012, 12:05:35 pm
The app notes for the AVR chips recommend a series resistor on the SPI lines if there are other SPI devices present, to prevent conflicts of interest while you are trying to program. Perhaps there is something like this going on.

Chuck the schematic on here!
9  Using Arduino / Programming Questions / Re: How to create a 38 Khz pulse with arduino using timer or PWM? on: April 22, 2012, 03:07:17 pm
If this can't be done in software then only I wish to go to a 555 timer.

You have several software options open to you. Or a 555 timer.
10  Using Arduino / Programming Questions / Re: How to create a 38 Khz pulse with arduino using timer or PWM? on: April 22, 2012, 06:32:27 am
I don't have any experience with the Mega, but it looks like it has quite a few timers knocking about. It seems like it should be possible to take one of the unused timers and Have it toggle one of the OCxn pins.

Take a look at the timer section in the data sheet, and also have a look here http://maxembedded.wordpress.com/2011/07/14/avr-timers-ctc-mode/ for more information on having a timer toggle a pin in the background purely through hardware.

Just make sure you don't tread on anything else that is using a particular timer, or there might be issues.
11  Using Arduino / Project Guidance / Re: Need some professional advice on my project ~~ on: April 22, 2012, 06:19:02 am
Automated grapefruit slicer?
12  Community / Bar Sport / Re: Arduino Sets Sail on: April 21, 2012, 03:14:56 pm
Take some solar panels perhaps, and maybe some data logging components.
13  Topics / Robotics / Re: A Hovercraft on: April 19, 2012, 01:33:54 pm
Perhaps you should tell us what exactly is not working with it, rather than leaving us to guess?
14  Community / Exhibition / Gallery / Re: High speed photography with arduino nano on: April 18, 2012, 09:38:13 am
Here's that diagram. I apologise for the quality, it was scanned on the photocopier at work.

As a bonus, here's an article with a really good photo that demonstrates what I mean.
15  Community / Exhibition / Gallery / Re: High speed photography with arduino nano on: April 18, 2012, 09:26:28 am
what do you mean exactly with "in a dark field manner"?

It's a studio lighting method to highlight the edges of transparent objects relatively easily - As focalist says the terms light field and dark field are used in microscopy, with slightly different meaning (as far as I understand it). This is a photo I took a few years ago using the technique - I have a more recent one with the filament lit, but it's not on the Internet and I can't find it.

In essence, place your object and frame up your shot. Now, cut a piece of black card so that it only just fills the viewfinder and place it behind the object as the background. Finally, use a large sheet of tracing paper and attach this to the back of the black background card to use as a diffuser. You can also use a softbox or bounce the flash of a (photographically) neutral wall.

When you take the photo, it should light the edges. Tada!

I'll draw a diagram and upload it in a minute.
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