Step by step manual for getting started with Shiftr.io (Software), Shiftr.io Pocket and Processing
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Also you need to make sure that you're running the latest version of Processing. If you have an old version or haven’t Processing installed at all, get it from their website.
Afterwards, download the processing-mqtt library from the GitHub repository. When the download has finished, move the library to your sketch folders libraries directory. More information about installing a library can be found here.
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Step XX – Store data (draft)
See the script from Joël
Remember: The script overwrites the current .csv file.