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Building a Smart Salt Level Monitor with ESPHome and the Wemos D1 Mini

Monitoring the salt level in water softeners or storage barrels is a practical use of IoT devices. This guide demonstrates how to configure an ESPHome-based salt level monitor using a Wemos D1 Mini and a VL53L0X distance sensor.

Project Overview

The ESPHome configuration provided is designed to:

  1. Monitor salt levels using the VL53L0X sensor.
  2. Provide real-time measurements via Wi-Fi.
  3. Offer an RGB status LED for visual feedback.
  4. Include a manual measurement trigger using a GPIO-connected button.
  5. Securely communicate with a smart home system through API encryption and OTA updates.

To see the full configuration, hop on my GitHub repository.

Hardware Requirements

  • Wemos D1 Mini (ESP8266 board)
  • VL53L0X Time-of-Flight Distance Sensor
  • RGB LED (common cathode)
  • Push button
  • Resistors (for pull-up configuration)
  • Breadboard and jumper wires
  • Power source (e.g., USB cable or 5V power supply)

Configuration Details

Substitutions

substitutions:
  name: salt-level
  friendly_name: "Salt Level"
  board: d1_mini

These placeholders make the configuration reusable and easy to adapt for different projects.

ESPHome Setup

esphome:
  name: ${name}
  friendly_name: ${friendly_name}

esp8266:
  board: ${board}

The ESPHome and board configuration initializes the Wemos D1 Mini with the project name and friendly name.

Wi-Fi Configuration

wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password
  ap:
    ssid: ${friendly_name} Fallback AP
    password: !secret salt_level_ap_password

The fallback AP ensures connectivity even if your main Wi-Fi credentials are unavailable.

Sensors and Updates

Distance Sensor (VL53L0X)

sensor:
  - platform: vl53l0x
    id: vl53l0x_sensor
    name: Reading
    update_interval: never
    unit_of_measurement: "%"
    accuracy_decimals: 0
    filters:
      - lambda: |-
          ESP_LOGD("custom", "Value measured. x= %f", x);
          const int BARREL_HEIGHT = 100;
          const int GAP = 15;          
          if(isnan(x) || x > BARREL_HEIGHT + GAP) { return 0; }
          else {
          return ((BARREL_HEIGHT - x *100)/(BARREL_HEIGHT - GAP))*100;
          }

This sensor calculates the percentage of salt remaining, factoring in barrel dimensions and measurement gaps.

Manual Trigger Button

binary_sensor:
  - platform: gpio
    pin:
      number: D3
      mode: INPUT_PULLUP
      inverted: true
    id: manual_measure_button
    internal: true
    on_press:
      then:
        - component.update: vl53l0x_sensor
        - logger.log: Button pressed

A physical button allows users to manually trigger measurements, which can be handy for quick checks.

RGB LED Status

light:
  - platform: rgb
    id: status_led
    red: led_red
    green: led_green
    blue: led_blue

The LED changes color to indicate various statuses:

  • Green: Measurement successful.
  • Red: Waiting for the next measurement.

Button and Restart Options

button:
  - platform: template
    name: Trigger Salt Measurement
    on_press:
      then:
        - component.update: vl53l0x_sensor

  - platform: restart
    name: Restart ${friendly_name}

The template button triggers a new salt level measurement, while the restart button reboots the device.

Putting It All Together

Wiring Diagram

  • VL53L0X:
  • SDA to D2
  • SCL to D1
  • VCC to 3.3V
  • GND to GND
  • Button:
  • One terminal to D3 (with a pull-up resistor)
  • Other terminal to GND
  • RGB LED:
  • Red to D5
  • Green to D6
  • Blue to D7

Uploading the Code

  1. Install the ESPHome dashboard.
  2. Create a new device using the provided YAML configuration.
  3. Compile and upload the firmware to the Wemos D1 Mini via USB.

Benefits of This Configuration

  1. Customization: Flexible settings for various barrel sizes.
  2. Security: Encrypted API communication and OTA updates.
  3. Ease of Use: Manual trigger and RGB feedback.
  4. Expandability: Add more sensors or features as needed.

With this setup, you’ll always know your salt level at a glance, whether through the RGB indicator or integration with your smart home system. Happy building!

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