I think my MLX90640 thermal camera is bad, can anyone confirm?

Question

I recently took delivery of a pimoroni mlx90640 thermal camera.

I followed the tutorial

https://everythingsmarthome.co.uk/howto/building-a-raspberry-pi-thermal-imaging-camera-mlx90640-guide/

And it all went well, except..

The output I get always looks the same no matter what or where I point it.

So no matter what I point it at the image looks more or less like that. mostly red area flickers white some and always that blue dot in the top left corner.

It looks like others have had sucess with that tutorial and I had no prob getting it to run.

ps: I did not use a portable screen/battery like in the tutorial. just my desktop rpi4 8gb.

Answer 1

I had the same problem - it was caused by a dead pixel which always returned a value of -273 degrees C. The software calculates the minimum and maximum temperatures returned from the array and plots the data based on these two values, but a Min value of -273 makes all the other pixels appear as the same colour. You can test whether this is the issue by finding the point in the code where the Min and Max are established and replacing the Min value with something more reasonable before plotting (e.g. 0 degrees?). I also found a bit of code to print all the pixel values - useful when I requested a replacement.