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I have IR receiver module based on AVR + TSOP, it gets IR signal from remote and passes it to RF tranceiver.

Now I want to make some improvements and try to connect output (IR Led pins) of IR remote directly to AVR bypassing TSOP to pass it's signal to RF.

Is it identical to use remote IR output as TSOP out to decode signal without "airing" it?

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  • \$\begingroup\$ @Wouter van Ooijen: Thanks for answer, how do you think, is there "good" way to decode such signal without many modifications? Maybe filter out carrier and invert signal? \$\endgroup\$ – Anton Mar 25 '13 at 15:08
  • \$\begingroup\$ I can't think of a better and cheaper way than to use a TSOP or similar. If the signal is too string you can exepriment with a piece of white paper between the LED and the receiver. \$\endgroup\$ – Wouter van Ooijen Mar 25 '13 at 15:47
  • \$\begingroup\$ Well, I agree, that is easiest way. But I just wanted to make it with less components. Anyway thanks. I will try to make some experiments :) \$\endgroup\$ – Anton Mar 25 '13 at 15:51
  • \$\begingroup\$ If you have a decent power that TSOP is one component. Very hard to beat that figure! If you power supply is dirty add one resistor and one capacitor... \$\endgroup\$ – Wouter van Ooijen Mar 25 '13 at 15:59
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No, it is not. The signal to the IR LED (and hence the IR signal itself) is modulated at a carrier of typically 36 or 38 kHz. The pictures below are from a TSOP datasheet. The top is the IR signal, the bottom the TSOP output. Note that the TSOP output is active low (low == IR sgnal is present).

enter image description here

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  • \$\begingroup\$ You might be able to take the signal right before the 38Khz oscillator and feed that directly to the AVR. Check and confirm if the signal is active high or active low. \$\endgroup\$ – Doc Mar 25 '13 at 15:19
  • \$\begingroup\$ The remotes I have seen (quite a few) contain a single chip (presumably a microcontroller), so the signal you refer to is some software concept inside this microcontroller. \$\endgroup\$ – Wouter van Ooijen Mar 25 '13 at 15:21
  • \$\begingroup\$ Well, for example this one: HITACHI CLE-876D Maybe there will be kind of "clean" signal right on PIN21? Ofcourse, it seems to be very remote dependent \$\endgroup\$ – Anton Mar 25 '13 at 15:28
  • \$\begingroup\$ PIN21 is one of the pins that scan the key matrix. Why would there be an unmodulated 'IR' signal on that pin?? \$\endgroup\$ – Wouter van Ooijen Mar 25 '13 at 16:01
  • \$\begingroup\$ Oops, I mean PIN31, obviously :) \$\endgroup\$ – Anton Mar 25 '13 at 20:31

protected by W5VO Mar 26 '13 at 0:25

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