ESP32 WiFi Scale with HX711 (and Optional OLED Display)

This project provides ESPHome configurations for building a WiFi-connected digital scale using an ESP32 and an HX711 load cell amplifier. An optional configuration adds an SSD1306 OLED display for local readout.

Features

• WiFi-enabled: Integrates with Home Assistant.
• Weight measurement: Uses HX711 and 4x half bridge load cells.
• Optional OLED display: Shows weight, date and time.
• Calibration: Instructions included in the YAML files.
• Restart switch: Remotely reboot the device from Home Assistant.

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Hardware Required

• ESP32 development board
• HX711 load cell amplifier
• 4x Half bridge load cells
• (Optional) SSD1306 OLED display (I2C, 128x64 recommended)
• Jumper wires, breadboard or PCB
• (Optional) 3D-printed or custom scale enclosure

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Wiring Diagram

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Configuration Files

1. scale.yaml (Basic WiFi Scale)

• For a simple WiFi-connected scale.
• No display; all readings are sent to Home Assistant.
• Sensors:
  • Weight (HX711, GPIO18/19)
  • ESP32 chip model (text sensor)
• Includes a restart switch.
• Calibration instructions in comments.

2. scale-with-oled.yaml (WiFi Scale with OLED Display)

• All features of scale.yaml.
• Adds SSD1306 OLED display (I2C: SDA=GPIO21, SCL=GPIO22).
• Displays:
  • Current weight (in grams or kg depening on yaml setting)
  • Current date and time
• Custom fonts for improved readability.
  • Add fonts to /esphome/fonts folder in Home Assistant

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Setup Instructions

1. Clone this repository and open in your favorite editor.

2. Fonts (for OLED version):
   Ensure the fonts/arial.ttf file is present in the fonts/ directory.

3. Secrets:
   Create a secrets.yaml file with your WiFi credentials:

   iot_wifi_ssid: "YOUR_WIFI_SSID"
   iot_wifi_password: "YOUR_WIFI_PASSWORD"

4. Flashing:

   • Install ESPHome.
   • Flash the desired YAML to your ESP32:

5. Calibration:

   • Place a known weight on the scale and follow the calibration comments in the YAML file.
   • Adjust the calibrate_linear filter as needed for accurate readings.

6. Home Assistant Integration:

   • The device will auto-discover in Home Assistant if on the same network.

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Usage

• View weight and device status in Home Assistant.
• (OLED version) See real-time weight, WiFi signal, and time on the display.
• Use the "Restart device" switch in Home Assistant to reboot the ESP32 remotely.

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Troubleshooting

• No readings? Double-check wiring, especially HX711 and I2C connections.
• Display issues? Confirm the OLED address (default is 0x3C) and wiring.
• Calibration off? Repeat the calibration steps with a known weight.