User Manual

2. Library Installation

If you are using version 1.6.2 or later of the Arduino software [https://www.arduino.cc/en/Main/Software],

you can use the Library Manager to install this library:

In the Arduino IDE, open the “Sketch” menu, select “Include Library”, then “Manage Libraries…”.

1. Search for “QTRSensors”.

2. Click the QTRSensors entry in the list.

3. Click “Install”.

If this does not work, you can manually install the library:

1. Download the latest release archive from GitHub [https://github.com/pololu/qtr-sensors-arduino/

releases] and decompress it.

2. Rename the folder “qtr-sensors-arduino-xxxx” to “QTRSensors”.

3. Drag the “QTRSensors” folder into the “libraries” directory inside your Arduino sketchbook

directory. You can view your sketchbook location by opening the “File” menu and selecting

“Preferences” in the Arduino IDE. If there is not already a “libraries” folder in that location,

you should make the folder yourself.

4. After installing the library, restart the Arduino IDE.

You should now be able to use these libraries in your sketches by selecting Sketch > Import Library

> QTRSensors from your Arduino IDE (or simply type #include <QTRSensors.h> at the top of your

sketch). Note that you might need to restart your Arduino IDE before it sees the new libraries.

Once this is done, you can create a QTRSensorsAnalog object for your QTR-xA sensors and a

QTRSensorsRC object for your QTR-xRC sensors:

This library takes care of the differences between the QTR-xA and QTR-xRC sensors internally,

providing you with a common interface to both sensors. The only external difference is in the

constructors, as you can see in the code sample above. The first argument to the QTRSensorsAnalog

constructor is an array of analog input pins (0 – 7) while the first argument to the QTRSensorsRC

constructor is an array of digital pins (0 – 19). Note that analog inputs 0 – 5 can be used as digital pins

14 – 19. For more details, see Section 3.

// create an object for three QTR-xA sensors on analog inputs 0, 2, and 6

QTRSensorsAnalog qtra((unsigned char[]) {0, 2, 6}, 3);

// create an object for four QTR-xRC sensors on digital pins 0 and 9, and on analog

// inputs 1 and 3 (which are being used as digital inputs 15 and 17 in this case)

QTRSensorsRC qtrrc((unsigned char[]) {0, 9, 15, 17}, 4);

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