Air Conditioner Controlled via PC or Internet - Attempt 3
After the first two failures, I decided that I should try a more electrical approach. What if I trigger the power button on the air conditioner's infrared remote control?
The pad labeled
KEY1 is the power button. After probing and tracing, I found that the
KEY1 input of the microcontroller was 2.3VDC when not pushed. When pushed, I measured 1.2VDC. Many button detection schemes involve turning the switch lines on and off, so I thought this voltage may have been do to measuring an AC component with a DC voltmeter. I could probably short the switch contacts with a transistor. I wouldn't even need to change my code because the transistor would take the place of the solenoid.
To test this, I sanded the lacquer off the traces and shorted them with a paperclip. The air conditioner didn't respond. I tried pressing the pad with my finger with no response. Then, I used the button itself, and the air conditioner responded.
As it turns out, the pad that pushes against the switch contacts is conductive foam. The remote probably uses an circuit involving varying capacitance. I didn't look too much more into it. At this point I decided to cut my loses and just build a proper frame.