Different Measuring with different AS7265X

Sensors Imaging
1

I am using three AS7265x breakout board for spectral identification.

I’ve three boards.

The board is behind a glass.

The main point its how to calibrate.

I put a mirror to take a measure with the full light spectrum, but I’ve different, values with each board.

In the data sheet of AS7265x indicates that The components AS72651, AS72652

and AS72653 are pre-calibrated with a specific light source.

AMS Device Type: 0x40

AMS Hardware Version: 0x41

Major Firmware Version: 0xC

Patch Firmware Version: 0x0

Build Firmware Version: 0x0

AMS Device Type: 0x40

AMS Hardware Version: 0x41

Major Firmware Version: 0xC

Patch Firmware Version: 0x0

Build Firmware Version: 0x0

But when I take the measures using the mirror

Board_1

10479,1894,3835,1779,1767,4932,489,593,541,247,472,128,2037,614,454,709,559,547,␍␊

10482,1895,3836,1780,1767,4933,489,593,541,247,472,128,2037,615,454,709,559,548,␍␊

10482,1895,3835,1778,1766,4932,489,593,541,247,473,128,2038,586,454,709,559,548,␍␊

Board_2

8492,1427,4053,1232,2007,5290,543,697,566,244,635,119,1932,622,370,727,858,703,␍␊

8491,1427,4053,1232,2006,5289,543,696,567,244,635,119,1931,633,370,726,859,703,␍␊

8492,1427,4053,1233,2007,5290,543,696,566,244,635,119,1931,622,369,727,859,703,␍␊

There is any explanation ? Is necessary to calibrate ?

2

Hi Pac_zaragoza,

Have you tried removing the glass and re-testing? If not, give that a try and see if it helps. Also, are you using the onboard LEDs or have you added your own? Finally, which example(s) from the [Arduino Library have you tested with?](SparkFun_AS7265x_Arduino_Library/examples at main · sparkfun/SparkFun_AS7265x_Arduino_Library · GitHub)

3

Thanks for your answer.

Yes we’ve tried with out the glass, and we are using the leds onboard

This is the test with out the glass.

(1)11889.7 7887.28 9869.96 4598.11 4530.43 5125 898.93 949.52 606.4 204.51 770.8 318.63 7988.14 2231.39 706.77 475.38 1166.92 2838.65

(2)9435.03 7273.13 10752.7 4625.85 5140.31 5990.58 959.49 1020.24 699.81 221.45 909.99 344.62 8208.72 2166.57 676.35 472.3 1654.27 3012.95

Still been quite different for the same situation.

4

I’m still working to find , the difference.

The example I’m using is Example2_basicReadingsWithLeds, but I’ve tried with all the examples.

And each device give a different value

With and without glass

All the tests were made with the same elements.

Is there any way to calibrate ? a patron to compare ??

5

patron is in Spanish :slight_smile:

is there any pattern to compare the values?

6

Finally I solved the problem.

The issue was to try to calibrate with the mirror cause in the data sheet came all the data with diffused light

ams Datasheet

Page 15

[v1-04] 2018-Jul-09

Document Feedback

AS7265x −

Typical Operating Characteristics

Note(s):

  1. Calibration and measurements are made using diffused light.

  2. Each channel is tested with GAIN = 16x, Integration Time (INT_T) = 166ms and VDD = VDD1 = VDD2 = 3.3V, TAMB=25°C.

  3. The accuracy of the channel counts/μW/cm² is ±12%.

  4. The light source is an incandescent light with an irradiance of ~1500μW/cm² (300-1000nm).

And with this information, I have a pattern to compare

And with the data sheet which you gave me in the first mail I solved mathematically

float value=((spectroRaw / GAIN * INT_T)/AREA_SENSOR);
calibration=PATTERN/value;
And with this information finally both equipments gave me almost the same value.
SENSOR 1 831 258 503 201 435 721 79 106 95 42 341 69 870 291 120 84 657 657
SENSOR 1 755 244 489 196 426 705 79 106 95 42 338 69 863 291 118 83 667 667
SENSOR 2 706 220 482 203 423 722 89 128 114 46 463 85 879 282 107 81 658 658
SENSOR 2 666 213 479 200 419 716 90 129 115 47 461 86 884 285 107 81 667 667
:smiley:

7

Hi Pac_zaragoza,

Thank you for your post, I think it might be very helpful.

I am in a similar situation, I want to calibrate my sensor for the environment where I use it, but I’m not sure how to do it.

Your suggestion could be the solution, but I don’t understand if by “AREA_SENSOR” you mean A = 0.75mm that is the dimentions written at page 13 of the datasheet. Also, what do you mean by the “PATTERN” in the “calibration” variable equation? and what is your reference model? where can I find one for my environment? Thank you so much for your help.