Door Open Sensor & Monitor

Here's the problem:

• In general, I try to keep the garage door closed except when it needs to be open.
• If I happen to be constantly going in and out (say I'm working in the yard), I leave it open.
• Occasionally, I will wake up in the morning and realize that I left the door open all night.
• Apparently, I need a reminder at the end of the day (before going to bed) to close the garage door if it is open.

Here's the solution: Using micropython programs on Raspberry Pi Pico-W microcontrollers

• A distance sensor detects the presence of the garage door in the open position
  • The sensor publishes the distance on a webserver
• A remotely located monitor periodically requests the distance value from the sensor
  • The monitor (located where I will notice it before going to bed) flashes its onboard LED at a rate which is tri-modal:
    • 5 flashes per second if the door is open (distance is below a threshold value)
    • 1 flash per second if the door is closed (distance exceeds the threshold value)
    • 1 flash every 5 seconds if the distance value was not received

Unanticipated problems (RF Interference with garage door opener)

Welcome to real life!

• As anyone who has ever impemented a simple solution to a simple problem realizes, Murphy's Law is there to remind us that we have overlooked something.
• My first solution used a VL53LOX VCSEL sensor to measure the distance to the garage door.
  • Problem was that when the VCSEL was running, my garage door receiver was not responsive to button presses from the remote radio transmitter.
  • Apparently, the VCSEL circuitry generates RFI at a frequency that interferes with the operation of the opener's radio signal.
• My next solution was to try a TF-Mini optical Lidar module that I happened to have laying around.
  • Same problem
• Eventually, I used the HC-SR04 ultrasonic distance sensor.
  • It did the job and didn't generate RFI that interfered with the operation of the garage door opener radio signals.