how to interface ir receiver output to microcontroller

[mightythrillers]

hii,
me and my team mates are doing a project on automobile theft prevention..
in that we are using ir transmitter and receiver..
is it possible to connect the output of the receiver directly to the microcontroller or any buffer is needed....
reply pl...

 

[cdh7]

Hi,

It depends. What kind of receiver are you using? If it's an IR module that does all the demodulation for you, then yes, you can connect it directly to the microcontroller. Just made sure the voltage levels are compatible (i.e. 3.3 vs 5 volts).

If you're working directly with a phototransistor or photodiode, then you'll need to design some kind of interface circuit.

Regards,
Chris

 

[mightythrillers]

sir...
we are just using TSOP 1738..
we faced the problem tat the output is always maintaining at high(5v) whether it is sensing or not....wat may be the problem sir....

 

[cdh7]

Hi,

Oh yes, I know that chip. It's basically an open collector output with a built-in pullup resistor. The output will normally be high and go low when a bit is detected.

Have you tried measuring the output before connecting it to your microcontroller? It may be that the microcontroller pin is configured as an output and holding the receiver pin high.

Also, are you sure that your transmitter is using the correct frequency? I think that the TSOP 1738 detects 38 kHz. The sensitivity drops sharply once you move a few kilohertz off center.

Regards,
Chris

 

[khansaab21]

The output of such modules will remain normally high. On detection of modulated wave it will go low. Please note that this module, just like many others of this type, gives inverted output. So, to get the original sent data, you have to invert the received data in the microcontroller.

Secondly, this module could be directly connected to microcontroller.

Thirdly, the input to this module must be modulated. For examples, you can visit rentron.com

The site has got alot of examples.

 

[welove8051]

hi, i think, you are using IR modules to detect vehicle movement. on my circuit, the output at collector transistor will be zero if light falling on the photo diode is interrupted.



regards
kj

 

[mightythrillers]

to welove8051,
sir we thought of visiting welove8051.com but in our college it is blocked because of the word"love"..
so pl can u explain working principle of the circuit u sent to me....

 

[welove8051]

to mightythrillers


check your pm