Infrared Sensors
Melexis thermometers and thermal arrays over I2C.
Detect
Scan the I2C bus and name what answers
MLX90632
Single-zone thermometer
MLX90640
32 × 24 thermal array, 768 pixels
MLX90641
16 × 12 thermal array, 192 pixels
MLX90642
32 × 24 array, temperatures computed on-chip
Every sensor here is read over I2C through the Melexis IO board, so connect that first.
When a reading comes out lower than expected, suspect the view before the maths. The object must fill the spot the sensor sees at that distance, and the field of view quoted in a datasheet is the angle at which the signal drops to half, so the real cone is wider than the figure suggests. Accuracy also assumes the sensor sits in thermal equilibrium: warm electronics beside it, a hand on the housing or a draught across it will pull the number off.