HX711 Wiring

The HX711 is the amplifier used by current Bee Thing configurations to read a load cell.

This page describes the shared points. Exact board pins are repeated in each hardware configuration.

Principle

The load cell connects to the HX711 module. The HX711 module then connects to the ESP32 with two digital signals:

• DT or DOUT for data;
• SCK or CLK for clock.

The firmware reads a raw value, applies configured calibration, then produces a normalized measurement in kilograms.

Image source: ShillehTek. The image illustrates the module principle; always use the Bee Thing table below for your configuration pins.

Load Cell to HX711

Exact names vary across modules and load cells. Follow the markings on your load cell and HX711 module.

Common terminals are:

• E+ and E- for load-cell excitation;
• A+ and A- for the main measurement signal;
• sometimes B+ and B- for a second channel not used by current Bee Thing configurations.

HX711 to ESP32

Configuration	DT / DOUT	SCK / CLK
Generic ESP32	GPIO4 by default	GPIO5 by default
ESP32-S3 Mini + WiFi + HX711	GPIO4	GPIO5
Waveshare + WiFi + HX711	GPIO39	GPIO40
Waveshare + 4G + HX711	GPIO39	GPIO40

If you change these pins, compile-time configuration must be changed with BEE_HX711_DATA_PIN and BEE_HX711_CLOCK_PIN.

Module Power

Use a supply compatible with your HX711 module and ESP32 board. Pay special attention to module output logic level: ESP32 GPIOs are not designed to receive 5 V.

After Wiring

Once the HX711 is wired:

1. flash the firmware for your configuration;
2. enter configuration mode;
3. configure calibration factor and tare;
4. test with a known weight.

See: Calibration and Diagnostics.