Data acquisition (0-2V) and transmission to a PC

hello,

I am a beginner in electronics and Arduino use. My project seems to me quite easy, but I have no idea about the feasibility and the need or not of some electronics components like resistance, amplificator...

About the materials ...
A machine have a BNC output 0..2V (checked with a voltmeter) resolved in time
I have an arduino uno
I have a computer

What I want to do ?

  • I wants to follow on the computer screen the voltage output on a plot like this across the time

    with choosen timescale (ms or sec)
  • And save the data in a two column file (time, value)

My questions :

  • If i just plug the machine like this :
    http://arduino.cc/en/Tutorial/AnalogInput
    Is it ok or should I say goodbye to my arduino ?

  • How can I nicely print the input on my computer screen ? Should I code or can I use software that accept COM as input, and do you know one of them ?

Thanks a lot for help !! :slight_smile: :slight_smile:

If the maximum voltage is kept below 5v then the Analog inputs will be able to read it.

You say the voltage is 2v and if so the range of the ADC would be 0 to 409 (1023/5*2). If you divide the voltage down to a max of 1v and uses the 1.1v internal reference voltage you will get better resolution.

How often do you need to take measurements? The Arduino ADC is not very fast - about 10k samples per second. It is possible to get a higher rate at the expense of lower resolution.

...R

analogRead() on the arduino will get you around 8K reads per second. However There is no way that Serial can keep up with this. You can read in bursts. However N*(2 bytes for the reading)*(4 the size of the mills/micros result) limits the number of readings at high speed.

Mark

You might want to take a look at a nice little freeware program called SimPlot. You can find it at http://www.negtronics.com/, about halfway down the page. It will let you easily plot up to four plots. It might not be what you want after you get it all going, but it is an easy way to test.

Hey,

Robin2:
You say the voltage is 2v and if so the range of the ADC would be 0 to 409 (1023/5*2). If you divide the voltage down to a max of 1v and uses the 1.1v internal reference voltage you will get better resolution.

Actually, I can play with gain of the machine and never go more than 1V to use the internal 1.1V reference.

Robin2:
How often do you need to take measurements? The Arduino ADC is not very fast - about 10k samples per second. It is possible to get a higher rate at the expense of lower resolution.

4k is OK, but 8k would be perfect. More often will not be usefull.

lar3ry:
You might want to take a look at a nice little freeware program called SimPlot. You can find it at http://www.negtronics.com/, about halfway down the page. It will let you easily plot up to four plots. It might not be what you want after you get it all going, but it is an easy way to test.

This software seems to perfectly match for testing, thank you ! At the end I think I will have to adapt or to code a specific software that match with my precise needs.

Thanks a lot for the answers. I will play with my Arduino this week and I keep you informed.