QTR-1RC reading problem

I have QTR-1RC sensor and I want to sense the black and white surfaces with it. The problem is when the machine starts, sensor first sense the ambient reflections and then sense the black and white surfaces. I just want to introduce the ambient reflections as white surface, how can i initialize it using software commands in Arduino. Thank you for your help.


Can you explain the situation in a bit more detail? One solution is just to use the raw (uncalibrated) sensor readings and do your own calibration on the Arduino.

- Ben

Hello again,

I’m using a wihte plastic material which have black marks on it (visualized in below figure). The main function of the machine is to drive the plastic material through one black mark to another. But when the machine is on idle state, there are no white or black surface behind the sensor. In this situation, machine should drive the material until sensor reads a white surface. I just want to introduce the sensor readings when the machine is in idle mode, as white.

Also, I think I’m using uncalibrated sensor readings with the “qtr.read(sensorValues)” command, but how I’m gonna make my own calibration on arduino and identify the idle sensor readings as white.

Thanks in advance.

I’m not sure what you’re looking to do is possible. The sensor has no way of knowing that there is no surface behind the sensor. It simply is reporting how much IR it is detecting. If that amount could be any value when nothing is behind the sensor, I don’t see how you can tell what is going on with any degree of confidence. Can you take steps to have better control over what’s going on with your system? If not, you might need to employ more than just one qtr sensor to know what’s going on.

- Ben