Please see the product pages for more information on how these sensors work. QTR-1RC and QTR-L-1RC reflectance sensor schematic diagram. QTR-1A reflectance sensor schematic diagram. QTR-L-1A reflectance sensor schematic diagram.
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). The modules come as compact, single-sensor units ( QTR-1A and QTR-1RC QTR-L-1A and QTR-L-1RC), 3-sensor arrays ( QTR-3A and QTR-3RC), or as 8-sensor arrays ( QTR-8A and QTR-8RC) that can be optionally split into a 2-sensor array and a 6-sensor array. 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. Top row: QTRX-HD-07, QTR-HD-07 middle row: QTR-3, QTR-1, QTR-L-1 bottom row: QTR-8. The current version of the library can be found on GitHub, and its documentation is here. This guide is for an older version of the QTRSensors Arduino library (3.1.0).
