Data Logging with SD Cards - Exploring Arduino: Tools and Techniques for Engineering Wizardry - page 305

time variables. These variables are printed to the serial console and to the SD
card log file.
After running this sketch on your Arduino for a little while, use your computer
to read the SD card and to open the log file; it should be populated with the date
and time and look something like Figure 13-21. Your spreadsheet software may
automatically change the dates into your local formatting.
Figure 13-21: Spreadsheet output from RTC SD card test
BuildinganEntranceLogger
Now that you have all the basic skills down, you can put them to use to build an
entrance logger for your room. You use the distance sensor from some of your
previous projects to create a basic motion sensor that can keep track of when
people enter or exit through a doorway. The logger will keep track of the times
of these events on the SD card for you to review later.