OK, so I think your next step should be to look through the Arduino program to see whether -1 is an expected value and what it means.
If you wave your hand in front of the sensor, does the -1 change to anything different?
OK, so I think your next step should be to look through the Arduino program to see whether -1 is an expected value and what it means.
If you wave your hand in front of the sensor, does the -1 change to anything different?