How to use QTR single sensors with Arduino?

I am using single sensors QTR-1A with Arduino. I need to obtain sensor values as single readings - not in an array as all examples do. Do I need to use QTR library and what function is for reading single analog sensor?
Also how emitter works with QTR-1A’s? Are these on all the time or these need to switch on with code?


You do not need to use the Arduino library to read individual sensors. You can use the Arduino analogRead() command to read the sensor attached to an analog pin. If you connect the VIN pin to 5V, the sensor’s IR LED will be on all the time. Generally, this is not a problem since the current draw is only 17mA. If you do not want the IR LED on all the time, you should be able to connect VIN to one of the Arduino pins and drive that pin high to turn the QTR-1A on, and drive the same pin low to turn the QTR-1A off.