This project uses BigClown's PIR module to control the power of a cat water fountain.

Parts:

1. BigClown
   1. Motion Detector Kit (https://shop.bigclown.com/motion-detector-kit/)
   2. Radio Dongle (https://shop.bigclown.com/radio-dongle/)
2. Smart Plug tp-link HS110 (https://www.tp-link.com/en/home-networking/smart-plug/hs110/)
3. Raspberry Pi 1 Model B Rev 2

Tools:

1. Home Assistant
2. MQTT Broker (in my case Mosquitto

When PIR sensor detects movement it sends message to Radio Dongle plugged to the Raspberry Pi which sends the message to the MQTT server. On the other side MQTT message is processed by the Home Assistant which then using the automation triggers smart plug and starts configured countdown.

In my deployment, I wanted to reuse old Raspberry Pi 1 Model B Rev 2 for the BigClown Radio Dongle, which was quite challenging as the standard installation was not supported on this particular old version of Pi. So plan B was needed, install it manually

# Install Python
apt install python3 python3-pip python3-setuptools
pip3 install --upgrade pip
 
# Install BigClown tooling
pip3 install --upgrade bcf bcg bch

When we have needed tools ready, let's create udev rule for the dongle:

echo 'SUBSYSTEMS=="usb", ACTION=="add", KERNEL=="ttyUSB*", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6015", ATTRS{serial}=="bc-usb-dongle*", SYMLINK+="bcUD%n", TAG+="systemd", ENV{SYSTEMD_ALIAS}="/dev/bcUD%n"'  | sudo tee --append /etc/udev/rules.d/58-bigclown-usb-dongle.rules

After the RPi restart Radio Dongle should be properly detected now:

# ls /dev/bc*
/dev/bcUD0

Now we can start gateway and start submitting the MQTT messages to the broker:

/usr/local/bin/bcg --device /dev/bcUD0 --mqtt-host 10.10.10.10

My Motion Detector kit came with the default firmware already loaded inside and by default, the module sends updates every time the motion is detected, but no more often than 1 minute. This is fine for my intended use, but if you would like to adjust the threshold, default firmware is available on Github at repository https://github.com/bigclownlabs/bcf-radio-motion-detector and in file app/application.c value of PIR_PUB_MIN_INTEVAL needs to be adjusted accordingly. Firmware flashing process if thoroughly described in the documentation.

I've chosen the tp-link HS110 as it can be remotely controlled via Home Assistant without any cloud account needed but anything can be used to control the power. Other option would be to use BigClown's Relay Module (https://shop.bigclown.com/relay-module/) and directly control the power of the water fountain, but I prefer the separate power control so I can move PIR sensor in the room freely, typically in the corridor, so the water would start flowing before the cat gets near the fountain

This is the excerpt of the configuration to support this scenario:

<file ~/.homeassistant/configuration.yaml> mqtt:

broker: 10.10.10.10
port: 1883

switch:

1. platform: tplink

host: 10.10.10.11

  name: "Water Fountain"

sensor:

1. platform: mqtt

state_topic: 'node/kit-motion-detector:0/pir/-/event-count'

  name: 'Counter'
  icon: mdi:smoke-detector
- platform: mqtt
  state_topic: 'node/kit-motion-detector:0/battery/-/voltage'
  name: 'Voltage'
  unit_of_measurement: 'V'

input_number:

slider_water_fountain:
  name: Timeout after PIR
  initial: 15
  min: 1
  max: 60
  step: 5
  unit_of_measurement: min

automation:

1. alias: Start Water Fountain by PIR

trigger:

    platform: state
    entity_id: sensor.counter
  action:
    service: switch.turn_on
    entity_id: switch.water_fountain
- alias: Vypnutí fontány po pohybu
  trigger:
    platform: state
    entity_id: sensor.counter
  condition:
    condition: and
    conditions:
      - condition: state
        entity_id: switch.water_fountain
        state: 'off'
  action:
    service: homeassistant.turn_on
    entity_id: script.timed_water_fountain

script:

timed_water_fountain:
  alias: "Set water fountain timer"
  sequence:
    # Cancel ev. old timers
    - service: script.turn_off
      data:
         entity_id: script.timer_off_water_fountain
    # Set new timer
    - service: script.turn_on
      data:
        entity_id: script.timer_off_water_fountain
timer_off_water_fountain:
  alias: "Turn off water fountain"
  sequence:
    - delay: '00:{{ states.input_number.slider_water_fountain.state | int }}:00'
    - service: homeassistant.turn_off
      entity_id: switch.water_fountain

group:

bcpir:
  name: 'PIR Sensor'
  icon: mdi:smoke-detector
  entities:
    - sensor.voltage
    - sensor.counter

fountain:
  name: 'Water fountain'
  entities:
    - switch.water_fountain
    - input_number.slider_water_fountain
    - automation.start_water_fountain_by_pir

</code>