[UPDATE] I can do this with the binary_sensor. So no real need to do this. The following code works for me:
- alias: Doorbell pressed
trigger:
- platform: state
entity_id: binary_sensor.doorbell
from: "on"
to: "off"
action: ....
[/update]
A push-button sensor is related to a binary sensor however the push-button sensor uses interrupts (callbacks) to trigger an event, instead of polling. Once the push button has been pressed the state changes to pressed. The state resets to not pressed after HA has successfully send an event.
Why is a push-button sensor is needed? The binary sensors can miss an event as if the button is pressed during a very short time, there is no guarantee that the sensor has been polled during that time.
Parameters to the sensor: GPIO-pin, rising/failing edge. optional: bounce time, pull_up_down
Intended use of the sensor: connect an old fashioned electric doorbell. (a debounce circuit is needed!)
Initial platform: Raspberry PI using rpi_gpio