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Topic: Open Source Data Logger Project Using the Arduino? (Read 37 times) previous topic - next topic

florinc


bsautner

Hey Guys

i've been working on an online data logging system built on google's app engine and i've pretty much decided to go open source with it. I'd really appriciate some feedback from Arduino users and perhaps even some help.

I've worked with data historians for 12 years and i wanted to write my own.

The system i built allows you do log time series data over a rest web service and your data is stored on google's infrastrucutre. I wrote a .net sdk and an way to view/record data on an android phone.  

i'm release the code soon under the MIT licence.  

I posted some code in my blog on how to wire devices into the web service - it works great, you can see values change in spread sheets and diagrams.

Anyway - i would really appriciate any feedback - you can contact me at bsautner@ (google's free email server)

thanks!

Ben

bsautner

Sorry, the web site for my data logging system is  http://www.nimbits.com

The source code will be posted on Google Code:

http://code.google.com/p/nimbits/

I spent 6 years working on this thing, so i hope it can be a good starting point for a cloud based data logger.

tspringer

Getting back to issues involved in developing an open source data logger based on the arduino:

It seems to me that the development of a shield to handle analog signal conditioning is a key step in making the data logger a broadly appicablel tool.  The ten bit resolution of the Arduino A/D converter (ADC) is not an issue as long the signal from sensors is relatively linear and varies so that the voltage change covers a large fraction of the 0 to 5 volt scale.  However, in many cases, the range of sensor outputs will vary over a much narrower range, and programmable gain amplifiers will be needed to adjust the dynamic range of voltages that are presented to the ADC. (e.g. resolution of the ADC will not be adequate if sensor output voltages range from 0 to 0.5 V).  Also, as many sensor's output varies logarithmically or exponentially with respect to the  stimulus, an exponential or logarithmic conversion will be needed to prevent loss of resolution at the low end of sensor input.   Based on my limited knowledge of OP amps, it seems that a shield to handle this kind of basic signal conditioning might not be too expensive to make. Of course this leaves out some more specialized signal conditioning needs (e.g. cold junction compensation for thermocouples), but if the shield could handle simple variable gain amplification and logarithmic transformation, it would allow the Arduino's 10 bit ADC to serve adequately for many, many data collection situations.

T

paolometeo

Hi, I am new in this forum. I am very interested to invest my time and some money in a data-logger development based on Arduino. I think that the problem must be divided into some steps:  how to interface sensors to arduino input, that can be solved with easy electronic circuits;
how to get arduino writing data on a SD card or USB pen drive;
how to get enough power autonomy for long data logging (months).

In fact I think to use this sort of device to monitor slow environmental phenomena (i.e. wine cellar temperature  :)).


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