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1  Community / Exhibition / Gallery / Re: Arduino and MLX90620 16X4 pixel IR thermal array on: February 09, 2013, 02:10:25 pm
small patch to calculate alpha_ij on the Arduino instead of a spreadsheet smiley

Code:
  float da0_scale = pow(2, -EEPROM_DATA[0xe3]);
  float alpha_const = (float)(((unsigned int)EEPROM_DATA[0xe1] << 8) + (unsigned int)EEPROM_DATA[0xe0]) * pow(2, -EEPROM_DATA[0xe2]);
  for(int i=0; i<=63; i++) {
    float alpha_var = (float)EEPROM_DATA[0x80 + i] * da0_scale;
    alpha_ij[i] = (alpha_const + alpha_var);
  }

Add it before the end of "void varInitialization(byte EEPROM_DATA[])".
2  Community / Exhibition / Gallery / Re: Arduino and MLX90620 16X4 pixel IR thermal array on: February 09, 2013, 01:56:35 pm
Below are the temperature values I get. The sensor is pointing towards a wall, so the temperatures should be almost the same.
Code:
-43.29 -25.06 -20.19 -14.03 -17.91 -9.14  -28.29 -14.59 -13.57 0.49   -4.85  -14.13 -10.58 -0.23  -2.00  -4.07  
-16.22 6.06   3.53   -4.15  2.72   8.47   2.10   -3.24  1.14   7.40   9.65   1.90   -7.16  7.83   6.58   3.11  
3.07   6.51   8.03   1.24   3.46   0.64   8.97   0.92   1.76   7.03   4.71   3.91   7.54   12.93  7.92   7.25  
-7.14  5.69   8.91   4.91   4.54   5.32   8.59   1.41   5.62   8.11   10.34  2.61   6.35   -8.17  0.14   1.68

This is the calibration information from my sensor:
Code:
a_ij:
-87 -82 -86 -84 -78 -76 -70 -74 -74 -71 -71 -69 -72 -66 -66 -70
-66 -65 -65 -68 -70 -64 -62 -64 -63 -59 -62 -64 -58 -59 -58 -62
-60 -59 -56 -57 -57 -51 -55 -52 -53 -50 -53 -54 -54 -50 -49 -51
-45 -45 -48 -47 -47 -43 -44 -48 -48 -43 -45 -42 -45 -39 -44 -44

b_ij:
-60 -60 -60 -68 -51 -55 -51 -60 -51 -51 -51 -68 -60 -43 -43 -51
-47 -51 -47 -43 -34 -51 -43 -51 -47 -43 -43 -47 -43 -43 -43 -43
-43 -43 -43 -77 -34 -38 -43 -51 -38 -43 -43 -38 -43 -34 -34 -34
-38 -34 -43 -34 -34 -34 -34 -34 -30 -30 -34 -30 -34 -38 -43 -30

alpha_ij:
1.01E-8 1.29E-8 1.37E-8 1.36E-8 1.16E-8 1.48E-8 1.35E-8 1.48E-8 1.26E-8 1.57E-8 1.54E-8 1.50E-8 1.37E-8 1.53E-8 1.60E-8 1.61E-8
1.41E-8 1.69E-8 1.71E-8 1.65E-8 1.61E-8 1.78E-8 1.79E-8 1.69E-8 1.56E-8 1.75E-8 1.84E-8 1.82E-8 1.55E-8 1.84E-8 1.89E-8 1.82E-8
1.68E-8 1.94E-8 1.91E-8 1.90E-8 1.66E-8 1.79E-8 1.89E-8 1.76E-8 1.64E-8 1.77E-8 1.84E-8 1.73E-8 1.65E-8 1.66E-8 1.68E-8 1.68E-8
1.36E-8 1.57E-8 1.65E-8 1.51E-8 1.49E-8 1.49E-8 1.57E-8 1.54E-8 1.46E-8 1.41E-8 1.47E-8 1.29E-8 1.30E-8 1.26E-8 1.39E-8 1.29E-8

If you compare the calibration information (espc. a_ij and b_ij) with the temperature you will notice a correlation. Is my sensor miscalibrated?
If you have such an sensor, please print the calibration data and post it here. I'd like to know if other sensors have the same huge variance between each pixel.

EDIT: This was caused by useing 3.3V instead of the recommended 2.6V supply, despite that fact the specification says "3.6V max" smiley-sad
3  Community / Exhibition / Gallery / Re: Arduino and MLX90620 16X4 pixel IR thermal array on: February 09, 2013, 10:04:13 am
i am also really interested in building my own cheap camera, but i cannot get any sensor here in Germany.
Is there any chance to get some? Any tips?

Sourcing the part seems to be a problem.
I ordered one here from as-electronic (Germany): http://as-electronic.net/shop/article_MLX90620ESF-BAD/MLX90620ESF-BAD-16x4-IR-Matrix-Temperatursensor.html?sessid=00GGQRHtRxMwPyV6emEwYDQGYumL5IhN16aK7VHOgiTEIWxkFn615nzhkErgWGDs&shop_param=cid%3D18%26aid%3DMLX90620ESF-BAD%26

Shipped within two days.
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