ESP32 with HX711 DIY Scale

Built a kitchen scale using a cheap load cell from a postal scale, an HX711 ADC, and an ESP32. Total cost: $8.

The HX711 is a 24-bit differential ADC specifically designed for Wheatstone bridge load cells. It communicates via a simple clock/data protocol (not I2C or SPI but easy to bit-bang). The conversion rate is either 10 or 80 samples per second, selected by a pin.

Calibration procedure: with the scale empty, read 10 averaged readings as the zero offset. Place a known weight (I use two 100g calibration weights), read another 10 averaged readings, and compute the scale factor. Store both in NVS (non-volatile storage). Long-term stability is limited by the load cell's temperature coefficient and creep — for kitchen use (±1g accuracy) it's excellent. For precision laboratory work, proper temperature compensation is required.