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I haven't started playing with SD card logging yet - however, a project I'm working on has a requirement for datalogging. I would like to be able to download the logged data (preferably as a .csv file) to a PC via USB - is this possible?

...and as I plan to download this data via USB, and not actually remove the SD card - is SD even the way to go about it - what other storage medium could I use?

Just trying to feel the water here - so to speak.
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I would like to be able to download the logged data (preferably as a .csv file) to a PC via USB - is this possible?
Yes, and no. It is possible to download the contents of the file to the PC as a stream of chars/bytes. What the application listening on the PC end does with that file is beyond the Arduino's control.

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...and as I plan to download this data via USB, and not actually remove the SD card - is SD even the way to go about it - what other storage medium could I use?
How much data are you talking about?
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So in theory, I could simply send a 1 to the controller by serial, and it would return all of the stored values, one by one so to speak? ...and careful serial prints with the commas in the correct place, would in some way or another - create a serial stream I could paste into notepad to create a .csv file?

In terms of how much data, 5 or so channels logged at 1Hz, another 4 or 5 logged at about 15Hz, in periods of roughly 30 minutes.
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I would like to be able to download the logged data (preferably as a .csv file) to a PC via USB - is this possible?

...and as I plan to download this data via USB, and not actually remove the SD card - is SD even the way to go about it - what other storage medium could I use?


I have exactly the same problem, so here is something that might help you get your feet wet.

When you trawl through all the blogsters and gurus, all they talk about is merely looking at information, just like in 1969, not actually doing something with it - i.e. all rumination and no practice.  The articles often start with promise but never deliver. It appears that it simply isn't practical to do it by wires with Arduino, although some secret hocus pocus may enable you to work it from the PC end. Just don't ask exactly what that involves. As I understand it, this is entirely because, while both a PC and an Arduino can use an SD card, they use differing methodology to do this.

The only person in the universe who understands this, and can actually explain it in a sensible manner, is a guy called Grumpy Mike, probably the gurus' guru, here:

http://arduino.cc/forum/index.php?topic=50181.0

So, what to do in order to save me a 12hour round trip to winkle out and read the SD?

I am now pretty sure that the easiest solution is to use cosm, which brings other assets to the table as well. In its normal use cosm is merely visual, just like the serial monitor but a hell of a lot prettier, and available to the world.

My cosm display is here    https://cosm.pachube.com/feeds/83153

The important thing is that cosm stores the information it uses for the display, and you can download that to your PC.  At the moment this is a little tedious, but I'm sure it can be streamlined.

http://community.cosm.com/node/1558

The irony here is that you don't need the SD card to do this! And, guess what? you don't need a clock either! Cosm does it all for you.
Having said that, I wouldn't dispense with either.......

Now, I have not explored all the details of this. There are matters of automation, housekeeping etc. etc. but what I have succeeded in doing is a fairly painless transfer of my datalogging information to Excel, just like a proper scientist......

There may be better ways, but I hope that helps!





« Last Edit: November 06, 2012, 01:03:59 am by NickPyner » Logged

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