QTR-1RC 2500 values only

using Arduino Mega

Only getting values of 2500 using QTRRCRawValuesExample

Only change is

#define NUM_SENSORS 1 // number of sensors used
#define TIMEOUT 2500 // waits for 2500 microseconds for sensor outputs to go low
#define EMITTER_PIN QTR_NO_EMITTER_PIN // emitter is controlled by digital pin 2

QTR-1C Pins

Grd is Grnd
Middle pin is 5 v
Out is Digital pin 3

I put Black electrical tape on piece of paper and out in front of sensor and nothing changes

Thank You

I am sorry you are having problems with your QTR-1RC Reflectance Sensor. A value of 2500 is what you should expect when your sensor is over the black line or it is not seeing enough reflection of the emitted IR. How far away are you holding the sensor from the paper? Please note that the maximum recommended sensing distance is about 9.5mm, with an optimal distance of around 3mm.

If you try sensing the paper at those distances and are still getting a returned value of 2500, could you try checking to see if the LED is emitting IR light by looking directly at it through a digital or cell phone camera while it is powered? Please note that some cameras have an IR filter strong enough to block this light (such as the rear-facing camera in newer iPhones) or make it very dim, but most should work fine.


I did not solder the headers, just stuck the header on the breadboard Once soldered it worked fine

I am glad you were able to find the problem and get it working; thank you for letting us know.

Good luck with your project!