Garage door stops when a car blocks it

A car parked too close to the garage can end badly for both the car and the door. I wanted the door to simply refuse to move in that situation.

The setup uses an ultrasonic sensor, which measures distance with sound pulses the way a parking aid does. It runs on a small chip programmed with ESPHome, a tool that makes such sensors talk to Home Assistant without much code.

The sensor sits in a printed holder outside, and Home Assistant blocks the door as long as something is standing in front of it. The holder and the code are published for anyone who wants to copy it.