Data Logging with SD Cards - Exploring Arduino: Tools and Techniques for Engineering Wizardry - page 278

There are countless examples of Arduinos being used to log weather conditions,
atmospheric conditions from weather balloons, building entry data, electrical
loads in buildings, and much more. Given their small size, minimal power
consumption, and ease of interfacing with a vast array of sensors, Arduinos are
an obvious choice for building data loggers, which are devices that record and
store information over a period of time. Data loggers are often deployed into
all kinds of environments to collect environmental or user data and to store it
into some kind of nonvolatile memory, such as an SD card. In this chapter, you
learn everything you could want to know about interfacing with an SD card
from an Arduino. You learn how to both write data to a file and how to read
existing information off an SD card. You use a real-time clock to add accurate
timestamps to your data. You also learn briefly about how to display the data
on your computer after you have retrieved it.
NOTE Tofollowavideotutorialaboutdatalogging,checkout www.jeremyblum
.com/2011/04/05/tutorial-11-for-arduino-sd-cards-and-datalogging/ .
YoucanalsofindthisvideoontheWileywebsiteshownatthebeginningofthischapter.
NOTE TofollowamoreadvancedtutorialaboutlogginglocationfromaGPS
receiver,checkout www.jeremyblum.com/2012/07/16/tutorial-15-for-
arduino-gps-tracking/ .YoucanalsofindthisvideoontheWileywebsite
shownatthebeginningofthischapter.
GettingReadyforDataLogging
Data logging systems are very simple. They generally consist of some kind of acqui-
sition system, such as analog sensors, to obtain data. They also contain some kind
of memory for storing sizeable quantities of that data over a long period of time.
This chapter highlights a few common ways that you can use an SD card
with your Arduino to record useful data. However, there are many uses for data
logging. Here is a brief list of projects in which you could use it:
■ A weather station for tracking light, temperature, and humidity over time
■ A GPS tracker and logger that keeps a record of where you've been over
the course of a day
■ A temperature monitor for your desktop computer to report data about
what components are getting the hottest
■ A light logger that keeps track of when, and for how long, the lights are
left on in your home or office
Later in this chapter, you create a data logging system that uses an infrared
(IR) distance sensor to create a log of when people enter and exit a room.