Scale Wireless Upgrade with ESP32

Inexpensive kitchen scales can be useful for a wide variety of purposes. As fairly simple devices, they don’t typically include features like wireless connectivity, but Liore Shai decided to change that by Wi-Fi-izing an Amazon Basics scale with an ESP32 board.

Conceptually, the hack is fairly straightforward: use the existing mechanical bits and load cell, and pipe data to an ESP32 for wireless dissemination. The trick here is that a load cell puts out a tiny voltage signal – in the microvolts range – largely useless to typical microcontrollers.

Shai therefore added an HX711 load cell amplifier for proper voltage measurement, which passes data along to the ESP32 via a protocol similar to I2C. The ESP32 then generates a local web server with this information. A 128x32 pixel OLED screen is employed for local user feedback, and a pair of buttons are used for setup.

Arduino-style code is available on GitHub, and a video of the scale in action weighing items can be found on this Reddit post. As for how this could come in handy, Shai suggests applications ranging from measuring 3D printer filament levels to pairing with Home Assistant to know when you need to stock up on coffee, sugar, salt, and more. Of course, this Wi-Fi add-on concept could be implemented with a variety of hardware, so the posted code and configuration might be just a starting point!