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This is a guide for how to interface the Parallax QTI light sensor with the Arduino.


The QTI sensor needs to be connected like this: the B label goes to ground, the W label goes to power, and the R label is the signal. I am using an Arduino Mega with the Sensor Shield so I just cut a servo cable and soldered it back together in the correct order. and

The QTI sensor returns low values for high reflectivity and high values for low reflectivity.