Package Delivery and Pickup Alert with a Smart Weight Mat

Cameras see a lot, but weight is simpler: a box makes the reading jump and pickup makes it fall. ESPHome reads an HX711 load-cell amplifier, and Home Assistant decides whether to notify you.

Mission steps

1. Build the platform

   Place the four load cells at the corners between two rigid boards (or 3D-printed cell mounts) so all the weight passes through them.

2. Wire the HX711

   Connect the four half-bridge cells to the HX711 in the standard bridge pattern, then DT to GPIO4, SCK to GPIO5, VCC to 3V3 and GND.

3. Flash and calibrate

   Flash the config, note the raw value empty and with a known weight, and put both into calibrate_linear.

4. Create the alerts

   In Home Assistant: weight rises over 0.3 kg → 'Package delivered'; weight drops back to zero while nobody is home → 'Package picked up'.

5. Weatherproof it

   Put the ESP32 and HX711 in a sealed box under the mat and run a USB cable to a covered outdoor-rated outlet or indoors.

Code

esphome:
  name: porch-mat

esp32:
  board: esp32-s3-devkitc-1

logger:
api:
wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password

sensor:
  - platform: hx711
    name: "Porch mat weight"
    dout_pin: GPIO4
    clk_pin: GPIO5
    gain: 128
    update_interval: 2s
    unit_of_measurement: kg
    accuracy_decimals: 2
    filters:
      - median:
          window_size: 5
          send_every: 1
      - calibrate_linear:          # replace with your own readings
          - 120000 -> 0
          - 520000 -> 2.0

Tip: test every script on the bench before installing it in a moving machine.

Questions