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I have a Linux computer (Ubuntu 20.04.5) and a Harman Kardon AVR51 A/V receiver which has a 3.5mm input jack for IR remote control.

My question is, if it is possible to send some kind of command from a USB port on that computer so the receiver for example turn on/off.

I've tried to Google it but from my searching no one tried this before. My idea is to use a USB to serial port adapter and send the data this way.

So in a short way, my goal is to control the AVR51 receiver from computer through cable.

Giacomo1968
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tapinko
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  • What does a 3.5 mm jack have to do with this? And why do you think it would work with a “hex” code? You are in way over your head here and nobody here can provide an easy solution for a question like this. – Giacomo1968 Jan 03 '23 at 20:38
  • "*My idea is to use a USB to Serial port adapter and send the data this way.*" -- If your AV receiver has an IR port, then what you really need is an IR transmitter (controlled by your "*Linux computer*") and a matching IR receiver. Typically an IR port will not accept a direct signal from a "*USB to Serial port adapter*", otherwise it would be called a serial port instead of an IR port. – sawdust Jan 03 '23 at 23:05
  • Now that I understand how the 3.5mm jack works, I think this is not a 100% bad or off-topic question, but the only solutions for stuff like this seems to be sending IR commands from a PC (with an IR transmitter on the PC) to the IR receiver on the A/V receiver itself. So I don’t think this would ever be some direct USB data connection to the 3.5mm jack protocol. But still an interesting question. – Giacomo1968 Jan 05 '23 at 19:16

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LIRC is software for sending and receiving IR commands on Linux. If you check the "Supported Hardware" section on the side bar of the site, there are a lot of options for transmitters from homebrew LED on serial ports to commercial products.

LIRC should also know what commands can be sent to your AV receiver.

Morphit
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  • This is interesting, but it seems like its would need a device to send the IR signals? It seems to me that the desire of the original poster is to bypass the whole IR receiver and just send commands directly to the 3.5mm jack itself. – Giacomo1968 Jan 05 '23 at 19:13
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    The device can be as simple as an LED, resistor and diode. If the electrical characteristics of the receiver are known, then a direct connection could be made, though I'd imagine some matching components would be needed. In any case the software would be the same. I think figuring that all out would be more trouble than just using an IR transmitter and the receiver's IR photodiode. Probably one for [electronics stackexchange](https://electronics.stackexchange.com/). – Morphit Jan 06 '23 at 12:50