Flora Color sensor

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adafruit_support_bill
 
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Re: Flora Color sensor

Post by adafruit_support_bill »

If the shroud is only open to the target and the sensor, light from the LED will not be able to reach the target.

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noanalyst
 
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Re: Flora Color sensor

Post by noanalyst »

Ok. That makes sense.

So if I am to understand correctly, the sensor only responds to the reflected light off the object from LED. Correct?

And since the LED light is dispersed in all directions (I assume), it would mean that even without a shroud, some of the light from LED will simply disperse into the environment and have no bearing on the sensor readings. Correct?

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Re: Flora Color sensor

Post by adafruit_support_bill »

The sensor responds to light from any source - direct or indirect. The purpose of the shroud is to block out any light other than what is reflected by the target from the led.

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Re: Flora Color sensor

Post by noanalyst »

If the sensor reacts to all light direct or indirect, under a normal setup (no shroud), how is it able to differentiate between the light reflected from an object right in front of it versus one light coming from an object 4x the distance away?

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Re: Flora Color sensor

Post by adafruit_support_bill »

It can't. That is what the shroud is for.

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noanalyst
 
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Re: Flora Color sensor

Post by noanalyst »

Ok. It is all coming together.

But this part on the website description of the product still confuses me:
"The sensor also has an incredible 3,800,000:1 dynamic range with adjustable integration time and gain so it is suited for use behind darkened glass or fabric."

If it is being used behind a piece of fabric for instance, and the LED is also covered by the fabric, will it work? It just seems to me that the fabric will significantly reduce the amount of light output from the LED such that the reflected light from the object which must also pass through the fabric will be significantly diminished.

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Re: Flora Color sensor

Post by adafruit_support_bill »

You did not mention anything about fabric between the sensor and your target. If that is true, then the situation is entirely different.

The fabric will filter the light from the LED twice: Once from the LED to that target and once again for the reflected light back to the sensor. And unless it is totally non-reflective black fabric, the fabric itself will reflect light back to the sensor and affect the readings.

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Re: Flora Color sensor

Post by noanalyst »

Ok. Is that a scenario where I should try to increase to adjust the gain to compensate for the fabric?

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Re: Flora Color sensor

Post by adafruit_support_bill »

As mentioned above, light attenuation is only one issue related to having a fabric layer between the sensor and the target. Please post a diagram and an explanation of exactly what you are trying to do.

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Re: Flora Color sensor

Post by noanalyst »

I don't have it set up yet but I am just trying to understand how it works so I don't over commit time to a project that may never be possible.

Basically I am trying to make a shirt that rings a buzzer when the correct color is put in front of it. But I want it to look like an ordinary shirt on the exterior so I do not want a bright LED light showing through it. If I sufficiently dimmed the LED by blocking it, from what you have told me the amount of light to the sensor will decrease. In order to ensure it is as accurate as possible, what are my options?

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Re: Flora Color sensor

Post by adafruit_support_bill »

If you are reading colors through fabric, you should probably not use the LED at all. You will get more light reflected back from the fabric than you will from the target. I don't see any practical way to restrict the field of view in that application.

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Re: Flora Color sensor

Post by noanalyst »

Sorry I did not understand. Can it work without the LED on?

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Re: Flora Color sensor

Post by adafruit_support_bill »

It can read colors with ambient light also. It is just not as precise and repeatable as with the led. You will also have a layer of cloth in front of the sensor. That will affect your readings too.

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Re: Flora Color sensor

Post by noanalyst »

Is there a way of turning off the LED or should I just block it with a black material?

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Re: Flora Color sensor

Post by adafruit_support_bill »

See "Interrupts and LED Control" here: https://learn.adafruit.com/adafruit-col ... ed-control

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