What Is the HX711? Load Cell ADC: Wiring, Calibration and Uses
The HX711 is a dedicated 24-bit ADC for load cells. It amplifies the very small voltage from a scale's Wheatstone bridge and converts it to digital; it is the standard part of digital scale projects. It takes the load cell's 4 wires and connects to the MCU with 2 wires (DT/SCK). The raw value is unitless; a calibration factor and taring are needed for real weight.
The HX711 is a dedicated 24-bit ADC for load cells. It amplifies the very small voltage difference from a scale's Wheatstone bridge and converts it to digital; it is the standard part of digital scale projects. For the concept, see what is a sensor.
What is the HX711 used for?
Digital scales, force measurement and strain-gauge projects. It takes the load cell's 4 wires (E+, E−, A+, A−) and connects to the MCU with 2 wires (DT/data and SCK/clock). With its built-in low-noise amplifier it reads sub-mV signals.
Connection
| Side | Pins |
|---|---|
| Load cell | E+ , E− (excitation), A+ , A− (measurement) |
| MCU | VCC, GND, DT (data), SCK (clock) |
Specifications
| Parameter | Value |
|---|---|
| Resolution | 24-bit |
| Gain | 128 / 64 / 32 (selectable) |
| Interface | 2-wire serial (DT + SCK) |
| Speed | 10 or 80 samples/s |
Watch out: calibration
The raw value is unitless; to convert it to real weight you must find a calibration factor (with a known weight). Zeroing is done by taring. Wiring and mechanical mounting directly affect noise and stability.
Equivalents
- HX710: a close relative.
- NAU7802: an I2C 24-bit bridge ADC.
- ADS1115: a general-purpose precise ADC (not load-cell specific).
Find it in our catalog
Use the HX711 search.