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24466  Forum 2005-2010 (read only) / Troubleshooting / Re: Program won't upload on second attempt on: June 17, 2010, 04:41:11 am
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I am using Version 12 of the Environment.

We are on version 18 now so an update is recommended. Especially as you are having trouble with new boards.
24467  Forum 2005-2010 (read only) / Troubleshooting / Re: analogWrite(3, 255) == digitalWrite(3, HIGH)?? on: June 18, 2010, 08:23:20 am
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I am also curious in what a mosfet is.

Basically it is a switch. When it is on it has a very low resistance. It uses voltages to switch as opposed to transistors that use current to switch.
see:-
http://en.wikipedia.org/wiki/MOSFET
24468  Forum 2005-2010 (read only) / Troubleshooting / Re: analogWrite(3, 255) == digitalWrite(3, HIGH)?? on: June 16, 2010, 02:30:01 am
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Could you either way elaborate on that calculation you're making

If the LED in the opto drops 1.25V then there must be 5 - 1.2 = 3.8V dropped across the resistor.
In order to have 30mA flowing through a resistor with 3.8V across it the resistor value must be 3.8 / 0.03 = 126.666666 ohms
Which is a value you can't buy so the closest would be 125R.

As to the original problem using analogue write automatically sets the pin to be an output where as the digital write requires it to be set separately. I know the code you posted does this but is there any chance this got missed originally?
24469  Forum 2005-2010 (read only) / Troubleshooting / Re: Trouble Reading Analogue Input on: June 15, 2010, 04:39:29 pm
That code looks OK but I would simply read the pin and print it out. Why make it complex when you have something fundimentally wrong to track down.

What you say you have done to wire it up also sounds right but as you are getting nothing out then either you have not implemented what you think you have or your arduino input pin is damaged. Try using the other analogue input pins just to make sure.
24470  Forum 2005-2010 (read only) / Troubleshooting / Re: Trouble Reading Analogue Input on: June 15, 2010, 07:02:09 am
Check the continuity on the ground.
Specifically when you measure the voltage going in to the arduino you put one probe on the arduino input, where do you put the other? Check that there is a path between the place of the other voltage probe and the arduino ground.

Then post the sketch because it might be that you are doing something wrong in software.
24471  Forum 2005-2010 (read only) / Troubleshooting / Re: Watchdog Timer burned! on: June 16, 2010, 04:39:08 am
See:-
http://arduino.cc/en/Hacking/Bootloader?from=Main.Bootloader
24472  Forum 2005-2010 (read only) / Troubleshooting / Re: Watchdog Timer burned! on: June 16, 2010, 02:33:09 am
Yes this is because the watchdog kicks in before there has been time to recognise the download.

The only way back is to re burn your bootloader (and fuses) with a programmer.
24473  Forum 2005-2010 (read only) / Troubleshooting / Re: DAC is eating my signal >:( on: June 16, 2010, 09:48:04 am
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At 100KHz and only two
devices on the bus the internal pullup should work.

But quite clearly it is not. Only one device works, either one separately is fine but two together is not. he is only using the internal pull ups. What other conclusion is there?

The signal looks appalling without external pull ups I am very surprised it works at all.
24474  Forum 2005-2010 (read only) / Troubleshooting / Re: DAC is eating my signal >:( on: June 16, 2010, 02:31:36 am
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Do I need stronger pullups than supplied internally through the Wire library?

Yes you need 4K7 pullups.
24475  Forum 2005-2010 (read only) / Troubleshooting / Re: Grounding issue with Analog ins?? on: June 15, 2010, 02:52:29 am
Yes the A/D specification on the chip says it is optimised for 10K so that is the one to go for if it suits the rest of the circuit.
24476  Forum 2005-2010 (read only) / Troubleshooting / Re: Grounding issue with Analog ins?? on: June 13, 2010, 12:51:05 pm
Make sure that the pull down resistor isn't too low otherwise it might load what ever you are trying to measure.
24477  Forum 2005-2010 (read only) / Troubleshooting / Re: Arduino Mega SPI Pin map on: June 09, 2010, 04:38:18 pm
See this thread:-
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1251780678
24478  Forum 2005-2010 (read only) / Troubleshooting / Re: dead mini... on: June 10, 2010, 10:00:40 am
Well compared with getting the old one off, putting a new one on is the easy part.  smiley-wink
24479  Forum 2005-2010 (read only) / Troubleshooting / Re: dead mini... on: June 10, 2010, 02:39:10 am
At 12V it is defiantly not going to be the regulator, that is well within it's voltage range.
The biggest problem you face is removing the IC. To do this you will need a hot air gun.
Failing that if you have a very fine pair of side cutters it is possible to remove the chip by snipping all the legs, although this sometimes damages the board.
Then clean up with solder bade and pop a new chip on, then burn the boot loader with a programmer.
24480  Forum 2005-2010 (read only) / Troubleshooting / Re: Strange voltage OUT of INPUT pin on: June 10, 2010, 09:23:48 am
So the switch is open, it is set to be an input in the software, you have a 10K pull up resistor and you measure 0.5V on that pin.

If all those are really true then it sounds like you have blown up the input pin on your arduino.

Alternatively you could have a voltmeter with a very low impedance, it's not set to current is it?
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