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4231  Using Arduino / Installation & Troubleshooting / Re: Arduino Ethernet on: November 18, 2011, 11:08:28 am
You cannot program the ATmega through the Ethernet interface.  The Ethernet chip is not active until the ATmega uses it.  You need to use a FTDI cable (or a ICSP) to program the ATmega before you can use the Enthernet chip.
4232  Using Arduino / Installation & Troubleshooting / Re: USB Port selection on: November 18, 2011, 11:04:04 am
You didn't answer my question:
quit the ide, disconnect the arduino.  when you reload the ide, does the same com port show up?

If COM3 shows up when the Arduino is disconnected, then COM3 isn't the Arduino.
4233  Using Arduino / Installation & Troubleshooting / Re: USB Port selection on: November 17, 2011, 11:28:00 pm
quit the ide, disconnect the arduino.  when you reload the ide, does the same com port show up?

did you reinstall the ftdi drivers?
4234  Using Arduino / Installation & Troubleshooting / Re: Problem with AVRDude on: November 17, 2011, 11:26:59 pm
how did you build your static library?
4235  Using Arduino / Installation & Troubleshooting / Re: Problem with AVRDude on: November 17, 2011, 08:22:36 pm
Where did you get " -DF_CPU=1843200UL"?

Shouldn't it be 1600000? (or are you running a 18.43MHz crystal.)
4236  Using Arduino / Installation & Troubleshooting / Re: [doubt] how do analog innput pins exactly work? on: November 17, 2011, 08:17:32 pm
so i must consider the AtMega as an ideal voltmeter with infinite resistance (with reason, of course, i'm not going to attack a car battery to it),

The only concern with a car battery is that it is 12V while the maximum input of Arduino IO pins is around 5V (depends on what voltage VCC is at). The current capacity of the source (in this case a car battery) is irrelevant. The Arduino is not an infinite resistance, it is a very high resistance.
4237  Using Arduino / Installation & Troubleshooting / Re: Arduino Mega on Mac OS on: November 17, 2011, 08:13:29 pm
First time I have heard of this on OSX.  Where did you buy your mega from?
4238  Using Arduino / General Electronics / Re: Increasing voltage output on: November 16, 2011, 09:32:33 pm
9v for an LED?  Something seems off here.
4239  Using Arduino / Programming Questions / Re: How to select the printf runtime library? on: November 16, 2011, 06:56:07 pm
Print to where?

Why not use the Arduino "Serial.print()" and "Serial.println()" instead?
4240  Using Arduino / Programming Questions / Re: Newbie - Java Question on: November 16, 2011, 06:52:49 pm
One of the examples on the Arduino app itself was the simple blinking LED on pin 13. So I thought that would be a good place to start trying to write in Java.

Write what?  The Arduino runs C++ code complied with avr-gcc.  That complied hex is loaded into the ATmega's program memory (aka flash) with a utility called avrdude over a virtual serial port.  The micro is reset and it starts running.

I'm confused how you writing something in java fits in there.
4241  Using Arduino / General Electronics / Re: How do laser rangefinders work? on: November 16, 2011, 06:14:34 pm
Remember that a timer is just a counter.  So it isn't (relatively) difficult to design and manufacturer a counter that runs at gigahertz speeds.

Also, they don't have to be digital.  You could charge a precision capacitor and measure the voltage, as another example.  (this is how high speed pulse triggers work in modern digital oscilloscopes.)

You could potentially interleave counters to get a higher effective resolution, again, a technique used by modern digital oscilloscopes.  (they have digitizers that run up to 100Gigasamples/s, which are many digitizers interleaved).

I would also imagine these devices are taking many, many readings and averaging to account for some drift in the components used.

Don't get wrapped up in the numbers. The techniques used are simple, just at a very fast speed...


If a timer is that fast then we could use a coil of fibre optic cables as a form of memory storage by measuring the cable and finding the smallest pulse size capable with the clock and then fill up fibre
You could, but that would be an expensive form of memory. If you think of dram, it works in a similar way.  Charge up a cap, measure the voltage.  Periodic refreshing is needed.  Same idea you have, but with light.
4242  Using Arduino / General Electronics / Re: NFC - what's needed? on: November 16, 2011, 03:57:47 pm
There is absolutely no need to cross-post in this (or any) forum:  http://arduino.cc/forum/index.php/topic,74087.msg597148.html#msg597148

Your questions can't be answered unless you explain what you are trying to do.  How you are going to use the devices matters in questions like these.
4243  Using Arduino / General Electronics / Re: How do laser rangefinders work? on: November 16, 2011, 03:53:09 pm
Can't do this with DSP with hardware that I know of, at least not with a naive implementation. Any idea how they pull it off?

Why not?  This isn't about DSP as much as it is about accurate timing.  Start a timer, send the light and then stop the timer when light comes back.  Subtract to determine the distance.  Your accuracy is limited by the speed of the timer you run.
4244  Using Arduino / Programming Questions / Re: Twitter Library on: November 16, 2011, 11:30:45 am
I had no problem downloading it either.

I did notice parts of the Arduino web site were broken last night.  Maybe it was a temporary issue?
4245  Using Arduino / Installation & Troubleshooting / Re: Upload issues - Mac OS X 10.4.11, Arduino IDE 0022 on: November 16, 2011, 09:53:20 am
 NOTE: had to delete Arduino 0022 and reinstal.  Appears that first use of Arduino IDE may install
    some libraries elsewhere - simply rebooting into 10.5.8 and running the same IDE as was used
    under 10.4.11 resulted in a missing lib error.
Conclusion: unknown OS X 10.4.11 specific issue

The IDE doesn't install any kind of libraries, system files, or extensions.  Searching the forum, you will find there are known issues with the Uno and 10.4.11.  Sometimes manually resetting works, sometimes it doesn't.
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