3 pins infrared receiver problem..help..

[tomaserif]

i have an ir receiver with 3 pins.. 1 supply, 1 ground, and 1 output.. when i tested it with an ir emitter there was nothing happened.. inside the datasheet, it said something about frequency.. do i have to flash the emitter with that frequency.. and how do i do that. i wnt to use it with a PIC16f877A

[Steve Joblin]

I'm not quite sure exactly what part number your IR Receiver is, but yes, the Receiver is looking for infrared light at a specific frequency (usually 38kHz i think).  You can use a 555 timer to generate the frequency.  Some microcontroller programming languages (like PBASIC for the Parallax Stamp II) provide special commands that will generate the frequency you need for your emitter.

The reason for the special frequency is to prevent false triggering (the IR light from a fluorecent bulb, sun light, etc all emit IR light so the receiver is designed to just detect IR light at a specific frequency).

[HDL_CinC_Dragon]

I have worked with the Basic Stamps and its a great learning tool. The command to output a frequency (be it sound or light) is "freqout pinNumber, Frequency" where pinNumber is the slot on the breadboard that it is attached to and the frequency is... well... the frequency. then on whatever pinNumber you entered, either connect that to a little speaker or to an IR LED and your good to go.... basically...

[tomaserif]

the part number is IRM-8601S.. now i know that i have to use the 555 timer.. but what kind of output does the receiver give? digital, analogue or pulse..? btw, thanks a lot guys!!

[Admin]

What kind of data are you trying to transmit? Text? or just measuring with an ADC?

If you are using a microcontroller, you can use the UART.

Also, the range on these things are pathetic (1-2 inches) if you dont modulate them to remove background noise.

[tomaserif]

I want to use it as an object detector on my sumobot..

[Admin]

Ok you will need to use an ADC port on your microcontroller.

Out of curiousity, run this experiment:
Attach power and ground to the reciever and transmitter.
Put a voltage meter on the output of the reciever and ground.
See if pointing the transmitter at the reciever changes the voltage on the reciever.

Also try it at different distances away from each other.

You can also try modulation. Go to page 5 and wire up the circuit as in the schematic. Apply an output pulse on the emitting diode (transmitter) as mentioned in earlier posts. Then just measure the voltage on the output of the reciever.

[tomaserif]

OK.. thanks a lot.. i really appreciate that.. i will definately try that circuit..

[HDL_CinC_Dragon]

Also, the range on these things are pathetic (1-2 inches)

Are you talking about the IR LEDS? I just recently took apart some old wireless headphone set thingy that you can plug into any standard audio jack and beam both audio channels to the headset receiver (another IR LED in the head phones). The range was decent too....

Ill post a picture of the xmitter (uses 4 IR LEDs) when I clear off some of my deskspace to take a pic of it with my webcam :-p

[Soeren]

Hi,

OK.. thanks a lot.. i really appreciate that.. i will definately try that circuit..

Most of the integrated IR receivers will need you to send short bursts of pulses, some will even require you to vary the pattern of the pulses.
The reason for this (on those that do) is, that the AGC subcircuit in the receiver will classify a continous burst (or continous burst pattern) as an error signal and as designed for, will ignore it.

[Soeren]

Btw. no A/D-C is needed, as the output from such integrated IR detectors are digital - most has an open collector output and as such need a pull up resistor on the input it's connected to.

[tomaserif]

guys... still have problems with the receiver.. i got the transmitter working at 38khz, but the receiver gave me nothing... now i'm confuse.. what is the output form.. is it because the receiver has already burned..

[Steve Joblin]

Confirm that you have it hooked up as per the spec sheet (the spec sheet describes the useage of two resistors and a cap.).

The output should be digital... that is, when it detects IR light, the output pin (the middle one) should go high.  Your PIC should simply test if the the pin that it is connected to is "high" or "low"... if it is "high", then there is IR light!

I am not completely familiar with that specific IR Detector, but the way I described it is the way it works for the PNA4601M IR Detector (although I don't use any external components like resistors or capacitors with it).

[tomaserif]

 .. i managed to make the receiver worked.. it is digital bul it is just like the type of receiver which Soeren said.. when i turn on the emitter the led in the receiver only blinked once and then acted like ussual.. the receiver needs some kind of ir pulse.. which is very confusing to me.. i think i will switch to the two pin receiver.. thanks again you guys for helping me out..   

[Soeren]

Hi,

The output should be digital... that is, when it detects IR light, the output pin (the middle one) should go high.  Your PIC should simply test if the the pin that it is connected to is "high" or "low"... if it is "high", then there is IR light!

Please don't give wrong advice, somebody might take it for the truth and ruin their components.

When holding the receiver pins down and looking at the window (the blob), the leftmost pin (pin 1) is the output, the middle pin (pin 2) is ground and the rightmost (pin 3) is Vcc, which should be +5V (+/- 10%).

The output of the IRM8601 has a built in pull-up resistor (22 kOhm) on what would otherwise be a normal open collector stage.

Feeding it correctly, it should give a LOW when it senses 38kHz pulses from an IR source (preferably with a 940 nm wavelength, but at close range, like a foot or two that doesn't matter).

But, as I mentioned earlier, a continuous wave will not work and should only give off a single short pulse. The datasheet suggests testing with 600 ?s bursts of 38kHz (that's around 23 cycles of the 38kHz carrier wave) with 600 ?s pauses in between (i.e. a 50% M/S ratio).

If the receiver has been connected the wrong way 'round, I wouldn't be too sure if it still works, but hey, it's still worth a try, as they're usually very easy to work with.