I'm wondering if anyone has attempted to do some wireless GPIO. I've done basic wired switches on GPIO ports that control lights and such. I'm trying to find information on how to just send high/low signals to the Pi, but wirelessly. I'd like to put some kind of RF transmitter in my doorbell on the ground floor to send a high signal when the button is pressed. I've taken the doorbell apart and have found voltage to power a transmitter, but I can only find serial modem type transmitters. I don't need anything as complicated as that, I just want it to act like if the button was physically connected to the Pi, so when the button is pressed, it connects the GPIO to voltage and triggers a high state on my Pi on my second floor, and when the button is let go, it would go back to a low state. Is there anyone out there who may have done this before?