IntermediateTest and Measurement
HX711 Tabletop Scale
Read a load cell with the HX711, tare the platform, and calibrate against a known mass.
Parts from the database
- HX711 × 1Load-cell ADC module
- ATmega328P-PU × 1Use on a compatible Arduino board
Other supplies
- HX711 breakoutCommon build supply
- four-wire load cell and rigid platformCommon build supply
- Arduino-compatible boardCommon build supply
- known calibration massCommon build supply
- USB cableCommon build supply
- jumper wiresCommon build supply
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Connections
- Connect load-cell E+/E− and A+/A− to the matching HX711 terminals using the load cell's datasheet; wire colors vary.
- Connect HX711 VCC/GND to the breakout's allowed logic supply, DT to D3 and SCK to D2.
- Mount the load cell exactly as its mechanical diagram specifies; the platform must not rub against the frame.
Build steps
- Install a maintained HX711 library and run its raw-reading example.
- With the platform empty, tare the reading and confirm it is stable.
- Place a known mass centered on the platform; calculate the scale factor from raw counts per unit mass.
- Repeat with a second mass and adjust the mounting if the readings differ substantially.
Software and firmware setup
Firmware is required, but a complete calibrated scale sketch is not included yet. First read raw counts from the HX711, then tare the empty platform and calibrate with a known mass. Verify with a second mass; load-cell wire colors are not standardized.
Test your build
After calibration, the known mass should read consistently near its marked value. This hobby scale is not a legal-for-trade instrument.
Troubleshooting
- Large drift often comes from a flexing mount, side loading, or poor wiring.
- If readings move when wires are touched, secure the cable and check load-cell connections.
- If data never updates, check DT/SCK mapping and the library example's pin constructor.
Safety and limitations
Use a low-voltage supply and do not overload the load cell. Keep the scale away from liquids and do not use it for medical or trade measurements.
Manufacturer and platform documentation
Community Notes for This Project
These are unverified visitor contributions, separate from the build guide and manufacturer specifications. Verify technical advice against the linked datasheets before relying on it.
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