GA1A12S202 - 3.3V => 10^5 lux ??? ( how )

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jb_swe
 
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GA1A12S202 - 3.3V => 10^5 lux ??? ( how )

Post by jb_swe »

The Arduino code - https://learn.adafruit.com/adafruit-ga1 ... sor/use-it
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float rawRange = 1024; // 3.3v
float logRange = 5.0; // 3.3v = 10^5 lux

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I don't get it ....

According to page 8, GA1A1S202WP_Spec.pdf

IF we make the assumption the sensor will deliver data linear up to 1E5 lux
The current at 1E5 lux would be 50uA, with a 68kOhm resistor that equals 3.4V output.

As I see it with ...

With a Vref (Aref) = 3.3 the logRange= 3.3/0.68=>4.85 ( Not 5 as above )
The highest reliable sensor value is log(55000)*0.68=>3.22V

Please explain... I don't get it

/JB

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Re: GA1A12S202 - 3.3V => 10^5 lux ??? ( how )

Post by adafruit_support_bill »

The graph is labeled as a "typical" response curve. As with all sensors, critical results require calibration against a standard under controlled conditions. Illuminance measurements in particular are especially sensitive to details like angle of incidence and the design of the integrator (if any).

With the example code, the bare sensor I tested tracks very close to my Gossen (dome integrator) in diffuse lighting conditions. As you might expect, it is much more sensitive to the angle of incidence and deviates significantly when used in direct light.

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