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Topic: [SOLVED]IR emitter / detector pair for digital high low? (Read 1 time) previous topic - next topic


Dec 03, 2012, 05:00 am Last Edit: Dec 03, 2012, 10:05 pm by Riccarr Reason: 1

I'm trying to create a circuit for a IR emitter/detector pair so that when the beam is broken it will read as a HIGH on the arduino digital pin. I'm very noob to electronics, I'm a programmer and am more into the program development on the arduino and have no electronics background.

I have fashioned my circuit after this example of a tach/rpm counter.


I have that circuit working using the LED so that if I break the beam then the LED will light. But instead of lighting the LED,  I want to run that signal to one of the digital inputs to the arduino.

I want to use digital pin high/low, as oppose to analog pins, because I'm actually wanting to use multiple sets of IR emitter/detector pairs and run them into a parallel/serial shift register (74HC156) so that I can feed many sensor signals into the arduino. My understanding is that the shift register will want high/low signals and won't work with analog levels???

I have my programming working with the 74HC165 and tested with multiple push buttons and received the signals; now I want to replace those buttons with the IR emitter/detectors. I'm getting fluctuating and constants signals, I believe, because the IR is always sending some level of voltage on the signal pin which I presume causes continuous high signals?

So, can the IR emitter/detector pair be used as I am wanting, in the scenario I've described? And if so, how would the circuit be set up?

Thanks for tips/comments.



Actually ... I have it working now. While I was testing with the IR pair as one of my input signals, I also had several buttons connected as other input signals. It seems one of the buttons is faulty and sending continuous high value and leading me to a wrong conclusion. So, I have 4 buttons and one IR pair (as a testing scenario) and inputs give accurate high/low states. This is terrific, although I am surprised that IR is working this way; I would have expected the constant power from the IR pair to throw off the high/low state for that input pin.

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