Author Topic: IR sensor operation  (Read 37 times)

jluc

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IR sensor operation
« on: June 17, 2020, 07:59:57 PM »
hello mario

I noticed that the ir sensors responded to the impulses of an IR remote but not to an IR LED lit continuously. how is that explained?
can i hope to achieve a simple interface with an IR led in order to randomly vary a parameter associated with an IR sensor?
thank you !
jluc

mario

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Re: IR sensor operation
« Reply #1 on: June 19, 2020, 06:15:36 PM »
Hi Jean-Luc,

That's a very interesting question. The sensors have their own IR LEDs and are measuring a difference between amount of light coming back when that LED is on vs. when it's off. That happens a few dozen times a second, and the purpose is to mitigate effect of ambient light. If you just shine a constant light on the sensor it won't do anything as there is no physical object to reflect the emitted light back. But the remote controller is sending alternating signal - what probably happens is that it goes on and off in a frequency close to what sensor is using, then it appears as if certain varying amount of light was reflected back (although it actually comes from the external source). I guess the result must be rather a chaotic excitation of the sensor?

It would be a simple software modification to allow all sensors to just react to incoming light, and turn their own IR LEDs off. I thought of doing it that way in v1 model as it also has CV pads that could override what sensor does, by directly applied 0-3V voltage. Maybe it's a good idea to add it into settings here in v2 model, to allow for such experiments.

There is also a 2-line CV input which is currently not used for anything, within the same menu it should also be possible to assign it to a combination of sensors - so when I get to modify this part of the code, I'd probably implement both functions at the same time.

Cheers,
Mario