I'm trying to build a device that alerts me when I leave home without locking the door. I have a little space inside the door (width 8mm x height 130mm x depth 8mm) where I plan to install the microcontroller, a small button that gets pressed when the piece of metal of the door slides in (door locked), a battery and a rf transmitter.
The questions are:
push buttons can detect the pushed/unpushed state of the button, or they simply give me a single "one-time" signal when the button is pressed ?
do you think the space available is enough for this project ?