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I actually think it's possible to detect the manual press of a heater push button. We can measure the voltage between output terminals of the optocoupler, which is connected in parallel to the external switch. When this voltage drops to 0 when there is no signal from Raspberry to do that, it means that external button was pressed. Two nuances here: a. polarity becomes important, we need to find which of the two wires is a (-) and connect it to Arduino's ground.b. If heater circuitry operates at much higher voltage than 5v it can fry Arduino when directly connected to its input data pin. Probably this can be resolved with a clamping diode or another optocoupler. I'll try to do something like this, but won't have time in the next few weeks :)
Thanks!Are you talking about the ability to detect an event when heater push button is manually pressed?
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