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Topic: [solved] Using a IR receiver to wake up microcontroller (Read 68 times) previous topic - next topic

arusr

Hello,
I have an Arduino that is set to wake up when pin 2 (interrupt pin) is grounded.  The rest of the application constrains the wake up state to waking up on ground, and the pin has internal pull up set.

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pinMode(2, INPUT_PULLUP);
I want to use a IR receiver like this to wake up the Arduino.

The IR receiver has power on 3.3V, GND on GND pin, and the output pin is on pin 2.  When I point a remote control at it, the IR receiver should wake up the microcontroller.  Some days this works, some days it doesn't.  I'm probably not understanding ho wthe IR receiver works.  When it receives a 38kHz 915MHz IR pulse, does it pull the output pin to GND or 3.3V?  Do I need a resistor in there somewhere like in a transistor circuit?  Or maybe I need to add another component?

At the end of the day, I need pin 2 to to go GND when the IR receiver sees IR light.  Not sure how to accomplish this.

Edit:  ah, I needed to add a resistor and capacitor in parallel to 5V and signal.

Grumpy_Mike

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When it receives a 38kHz 915MHz IR pulse,
WHAT?

Where doe the 915MHz come from? Is it a typo?

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does it pull the output pin to GND or 3.3V?
Yes. It gives a pulse signal that goes from ground to Vcc repeatedly. It sits at Vcc normally but any activation produces pulses that give you both logic levels so it will not matter.

However why do you say Vcc is 3.3V, this is a 5V device are you running it at 3v3?

arusr

lol.  915nm IR light.  Got my wavelengths and frequencies mixed.

I'm running at 3.3V (Arduino clone).


I'm not sure why it keeps grounding out...or something.    The arduino is waking up when there's no IR signal, so something flaky is going on.  I thought maybe I"m doing something wrong.

Grumpy_Mike

As I said that sensor is designed for 5V, it will not work reliably at 3v3.

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grounding out
No idea what that means.

Modulated IR, output is high / low pulsing. No modulated IR output is high.

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