Dear Mike, dear other MLX90621 users,
I ordered an Open Source Thermal Imager via Sandboxelectronics last month. It arrived right after Christmas.
It runs fine using a MLX90614 sensor, but when I try to use it with a MLX90621 (BAD) sensor array, the sensor is detected as MLX90621 and for a very short time (less than one second), I can see a temperature pattern on the TFT screen, which then turns into blue uniform color. The ambient temperature is always shown as 27.3x °C.
I think this behaviour is rather a sensor / library problem than an issue of your Thermal Imager. I also use the MLX90621 in a multicopter for surface temperature detection. The first array I bought, runs smoothly on an Arduino Mega using Max Ritter's library and robinvanemden's "readTemperatures.ino".
But three other arrays I bought, show the same issue, using them on an Arduino. The serial output is always:
readIR
readIR
readIR
readIR
cpix -3873
nan nan nan nan nan nan nan nan nan nan nan nan nan nan nan nan 0
nan nan nan nan nan nan nan nan nan nan nan nan nan nan nan nan 1
nan nan nan nan nan nan nan nan nan nan nan nan nan nan nan nan 2
nan nan nan nan nan nan nan nan nan nan nan nan nan nan nan nan 3
ambient 27.37
config 18236
ptat 61617
The strange thing is: using the Melexis evaluation board for the 90621 the arrays work fine.
I doublechecked all possibilities (pull up resistors, decoupling capacitors, stable voltage supply 2.6 / 2.7) I could think of, but I always end up with the "nan" readings.
I am an agricultural engineer with very limited skills in programming.
Could you give me a hint what might cause the issue with the MLX90621 using it with your Thermal Imager and the Arduino?
Best regards and a Happy New Year!
Jans