Is it possible to connect an IR diode to the phone's audio output?

Question

Electronics

There is an idea that I would like to work out in theory:
1. Is it possible to send data (say 2 bytes) using a mobile phone to another mobile phone using the audio output of mobile phones. For example, using IR transceivers (software is not a problem to write)
2. What is the maximum distance that data can be transmitted in this way under normal conditions (open area, daylight, interference in the form of rain).

Answer 1

Theoretically, 2 bytes can be sent without additional diodes: by flashing the phone screen. On the receiving phone, respectively, use the camera.

Answer 2

Can.
On the ixbt forum, I read how to enter the service menu of TVs in a similar way. Only there was used not a telephone, but ordinary speakers. (following the link of paragraph 2.1 of paragraph 3, under the spoiler)
The second example: a miniterminal from a private bank

Answer 3

Here is a diagram for connecting an IR receiver through the microphone input to a computer. Lirc works well with this scheme. Maybe it will work with a phone.

Answer 4

You can transfer data.
The "remotes for home appliances from smartphones" projects use 2 IR LEDs turned on in different polarities to provide the desired frequency:
http://rtfms.com/episode-4-turn-your-iphoneandroid-mac-pc-player-etc- into-a-universal-remote.htm
It is probably also possible to use the microphone input for reception, but I did not come across ready-made solutions.

Answer 5

There was also something similar on Habré, but only about sending data. I did not meet about the reception ...