User Manual

1. Introduction

QTR sensor size comparison. Top row: QTRX-HD-07, QTR-HD-07;

middle row: QTR-3, QTR-1, QTR-L-1; bottom row: QTR-8.

The Pololu QTR reflectance sensors carry infrared LED and phototransistor pairs that can provide

analog measurements of IR reflectance, which makes them great for close-proximity edge detection

and line-following applications. The modules come as compact, single-sensor units (QTR-1A

[https://www.pololu.com/product/2458] and QTR-1RC [https://www.pololu.com/product/2459]; QTR-L-1A

[https://www.pololu.com/product/2454] and QTR-L-1RC [https://www.pololu.com/product/2455]), 3-sensor

arrays (QTR-3A [https://www.pololu.com/product/2456] and QTR-3RC [https://www.pololu.com/product/2457]),

or as 8-sensor arrays (QTR-8A [https://www.pololu.com/product/960] and QTR-8RC [https://www.pololu.com/

product/961]) that can be optionally split into a 2-sensor array and a 6-sensor array.

The modules are available in two different output formats: the QTR-xA outputs an analog voltage

between 0 and Vcc that can be measured by an analog-to-digital converter (ADC), and the QTR-xRC

outputs require a digital I/O line capable of driving the output line high and then measuring the time for

the output voltage to decay (which provides an analog measurement of reflectance).

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