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A hardware interface, maybe?

A project log for Reverse engineering a Fujitsu Air Conditioner Unit

I want to automate my air conditioning. Unfortunately, the Fujitsu remote controller we have doesn't have IR. It does have serial though...

Myles EftosMyles Eftos 08/12/2020 at 22:561 Comment

[Eddi] made a great find! This is a discussion on EEVBlog on decoding the interface on an LG system. While I think the comms protocol is different, there is a suggested schematic for a Dual Comparator Serial Bus transceiver that looks like it is exactly what we need. I have ordered some LM393s - I'll build the circuit one they arrive. https://www.eevblog.com/forum/projects/where-to-start-trying-to-decode-a-data-stream/25/

In the mean time, I'll pull the second unit I have out and see if I can get it running in slave mode. That was I can listen to it's TX pin, and see if I can work out what it says.

Discussions

jaroslawprzybylowicz wrote 09/08/2020 at 08:50 point

This looks exactly like serial protocol that I reverse engineered for Fuji Electric AC unit. I might have some answers for you. https://www.manualslib.com/manual/1239980/Fujitsu-Aoyg30lat4.html?page=36#manual is where I started. The diagram should reveal how 1-wire communication is converted into Tx and Rx of the MCU in the indoor unit.

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