nuElectronics datalogger shield

My datalogger shield arrived today, and I’m excited! I didn’t quite “get” what the device was before I had it in front of me, but for £11 I was willing to spend the money to know more. This post is an attempt to alert you to something I think you too might enjoy “playing” with. I am not connected with nuElectroics, and things in the following could be wrong.

http://www.nuelectronics.com/estore/index.php?main_page=product_info&cPath=7&products_id=20

This is what you get… as I understand it so far!

A decently made shield to plug into an Arduino.

On it:

  1. A Dallas 1302 RTC (time of day chip), hardwired to the Arduino’s digital pins 3, 4 and 5. The (short!) demo program which is available for download from the nuelectonics site shows two simple calls to functions inside what I would guess is the standard Arduino DS1302 library… the first call sets the clock… you’d need to do this once. After that, an on-board battery will keep the RTC running even when the Arduino has not power. And the other simple call fetches the the current date and time from the RTC for you.

  2. A selection of physical connections (sockets) you can plug external devices into. Most have +5, gnd, and one of the Arduino’s analog lines. N. B.: There is a reason that the nuelctronics documents say “one wire”, not 1-Wire. The latter is a complex protocol patented by Dallas. On the nuelectonics board, the “one wire” “interfaces” are really just physical connection points giving you access to Arduino analog input lines, 0-5. Remember: You CAN use an Arduino “analog” input for digital input OR OUTPUT if you wish to. (D14-19, 18 and 19 also being the SDA/SCL lines.) Furthermore, there are ways to use most (any?) of these “one wire” connections to talk to devices from the Dallas “1-Wire” ™ family. nuelectronics have already done the code for reading a DS18B20, for instance.

While most are “one wire”, two others bring 5v, gnd, and TWO analog lines to a socket for your use. (ADC2&3 / ADC4&5. Beware… all four are ALSO available via “one wire” connectors.)

  1. The physical device, and some electronics, to allow you to write to an SD card. Now… as I understand things, and only “reporting” things clearly in the demo software… the writing to the SD card is pretty BASIC. But this is GOOD! (Takes less memory; less to go wrong) And MAYBE the shield has enough for FANCIER “disk” i/o to the SD card… but, for now, for £11, don’t expect to be able to do more than…

OUTSIDE of the Arduino: Format the card, create a file on it that consists simply of lots and lots of space characters
With sketch not yet running, insert SD card in datalogging shield attached to Arduino.
Start sketch.
Early in sketch call routine to mount the SD card
Then use “seek” and “write” commands to write bytes into places in the file that used to be a bunch of spaces.

LATER, again outside of the Arduino, you read back what you have written, and pass it on to a bigger computer for whatever you wanted the data for.

So… no threat to Windows yet… but perfectly adequate. I hope that explanation helps you see what the system will… and won’t… do. For more on that aspect, see…

http://elm-chan.org/fsw/ff/00index_p.html

(It is the PETIT FatFs that I “know” works… not the FULL FatFs… but I bet the full version is a possibility, with the same hardware, if you want the software overheads.)

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I see no reason why you can’t work with the demo program and take it to bits, to make sure you inderstand each element…

Try the RTC functions… in isolation
Try very simple “write to SD” programs
Try using the shield to conveniently connect sundry sensors… I infer from the
range on offer at nuelectronics’s site that sensors of those sorts can be
connected, at least.

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This isn’t the “full datalogger” I, for no good reason, envisioned. It IS a nice shield to help you connect up the elements for many, many datalogging applications YOU might care to implement.

I like the simplicity of the board. While it targets datalogging applications, it has been left “general” enough that you can do many, many other things with it. Any “things” that need an SD card and/or a RTC will get a big head start by using this shield.

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“What’s it good for?” Anything YOU want to program it to do… with the resources outlined above. You can’t just “plug it in, turn it on”… but with a LITTLE programming skill, you can create Good Things!

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So! I’m all enthusiastic… but haven’t ACTUALLY plugged the thing in yet. :-[

Anyone out there already using one?? How’s it doing?