Digital Weighing Scale
About this project
WeighCore connects a 1kg TAL221 load cell to the HX711 24-bit ADC module and builds a precision digital scale with sub-gram resolution. The HX711 reads the Wheatstone bridge differential voltage from the load cell — a tiny signal in the millivolt range — amplifies it 128 times, and converts it to a 24-bit two's complement result over a custom serial protocol (neither SPI, I2C, nor UART). The Arduino averages 10 consecutive readings, applies a calibration factor, and displays weight in grams on a 16×2 LCD. A hardware tare button (D2) zeroes the scale in one press. A serial command interface accepts TARE, CAL, INFO, and UNIT commands from the Serial Monitor. An overload LED (D3) warns when weight exceeds 90% of the rated capacity. The calibration procedure — placing a known weight and typing CAL 200 — teaches the universal concept of ADC scale factors: every voltmeter, thermometer, pressure gauge, and load cell in the world uses this same calibrate-with-known-reference approach. The project covers five precision measurement concepts: Wheatstone bridge differential voltage measurement, the HX711 custom serial protocol (25 clock pulses for data + gain selection), 24-bit Σ-Δ ADC architecture, calibration factor derivation and application, and running average noise reduction. Build time: 3 hours.
What you get
- Complete, commented source code
- Full components list with quantities
- Pin-by-pin wiring guide and connection table
- Step-by-step upload and testing guide
- Project report (.docx, IEEE style)
- Presentation slides (.pptx)
