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I have a Panasonic air conditioner which comes with a wired remote controller CZ - RD513C attched to the wall and has no infrared. I want to make a circuit connecting to STM32F746 to automate the temperature control from the STM display, e.g. set Monday morning 8 am 27°C.

There are two wires coming out of the cable remote controller, one is a ground and the other is a power + signal line. I'm thinking using a circuit like below to control. However, it seems there's a frequency difference problem, the carrier frequency of TDA5051A is 132.5 kHz, but the AC control signal frequency is 18.75kHz. Does anyone have any idea how this could work out?

Control CircuitTDA5051A parameters

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closed as off-topic by Chris Stratton, JRE, RoyC, Warren Hill, evildemonic May 14 at 14:48

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    \$\begingroup\$ Find out which line is which, sniff data, reverse engineer or make a map table, implement in your favorite MCU. Done. \$\endgroup\$ – winny Aug 23 '17 at 18:46
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    \$\begingroup\$ Stick an oscilloscope on the air conditioner's remote control power and report back with a plot. Do this if it's a "safe" voltage like 5V or 12V. You might have to put a series capacitor with a scope probe or set your scope input to AC coupled so that you can see the 18 kHz signal riding on top of the power better. ASK is pretty straightforward and I think folks here can help reverse engineer if you can get good scope plots. \$\endgroup\$ – Vince Patron Aug 23 '17 at 20:45
  • \$\begingroup\$ fCR = fOSC /64 but can fOSC go down to 18.75kHz x 64 ? Seems not from specs \$\endgroup\$ – Sunnyskyguy EE75 Aug 25 '17 at 19:44
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    \$\begingroup\$ I'm voting to close this question as off-topic because it is a usage question unsupported by any technical findings which could lead to a solution, which has been abandoned for the better part of two years \$\endgroup\$ – Chris Stratton May 10 at 23:50