IR Beacon Tranciever Pair

Link to product:

Modulation frequency is 56Hz, so can I recieve the IR signal transmitted from the beacon with just a TSOP34156 (hooked straight to the microcontroller)?

I tried but the logic would not go low, maybe just a little drop in voltage.

What did I do wrong, or what can I do to “recieve” IR signal from the beacon?


I am sorry you are having problems reading your IR receiver. You should be able to connect the IR detector module’s output signal directly to a microcontroller. Could you tell me more about your setup? How do you have the sensor connected? What microcontroller are you using? Could you post pictures of your setup?

- Jeremy

Well actually the beacon pair work well together (both of them programmed by pololu to do recieve and transmit), but i’m trying to do a “separate” reciever with TSOPs.

This is what I did:

Before hooking onto the microcontroller I used a DMM to measure the voltage but did not get a near 0 voltage for the low state (when the 56kHz signal is detected).

I am expecting a constant 0 logic from the TSOP (I might be wrong)

I am using a raspberry pi with the GPIOs and with voltage of 3.3V (instead of the ‘5V’ in the diagram), but it should not make a difference i hope, since the TSOP can take in a voltage of 3.3V

The connections in the diagram look correct. According to the datasheet, the maximum voltage for output low is 250 mV. Is this what you see? Do you get any difference in the output voltage when the IR beacon is and isn’t visible to the sensor? Could you post photos of your setup including all your connections?

- Jeremy

No, i dont get anything close to 0v

Lets say i got initial high of 3.3V, maybe dropped to around 2.7V when the beacon is active…ill post up more pictures with my DMM once i get access to my system again tomorrow…

One weird thing is the beacon need not be in the line of sight, powering it up anywhere around the TSOP will cause it to trigger (will come to this issue later)

One question, should I get a constant low? Or is it somewhat “coded” with binary such that I get a series of 0s and 1s that i have to use an oscilloscope to see it?

Just powered up the TSOP with a power supply and testing with the beacon, beacon isn’t powered up on the left picture. Using a voltage of 5V.

The IR LEDs on the beacon are pulsed at about a thousand times a second and they do not output a steady 56kHz modulated signal. This means the individual sensor will only output a low signal for short period of time, and your voltmeter will not be able to display that information (instead you get an averaged value that is only slightly lower than your source voltage). If you have access to an oscilloscope, you might try reading the output of that sensor to see that the signal does indeed go low for those short periods. If you plan on using the sensor to sense the IR beacon with a microcontroller, you should have the microcontroller sample the signal to see if it goes low.

As for the sensor detecting the IR beacon when it is not in the line of sight, it is possible that signal is getting bounced around and picked up by the sensor.

- Jeremy

Thanks for the info! I’ll see what can be done about it.

Is there any way to make the TSOP “see” in one direction? Meaning it will not pick up signals that is not in its the line of sight?

Put the package in an IR-black tube to narrow the field of view.