I am currently in a project using the QTR-8RC sensor with a black line on white paper. I used the example code almost copy/paste and am getting these outputs. All but two of the sensors appear to be reading the line accurately but I am also not sure what is going on in the calibration.


You can find a description of what our library’s calibrate() function does in the library documentation. During the calibration phase you should move your array so that each individual sensor is exposed to both the black line and the white paper.

Can you post some pictures of your QTR senor array that show all of the physical connections, including close ups of both sides of the board? The easiest way to confirm whether each of the sensors is working is to upload the appropriate raw values example program from our QTR sensors Arduino library with minimal modification, point the sensors away from any surfaces, and closely cover each sensor one at a time to see if each returned value changes independently. Can you try that?

- Patrick