SparkFun OpenScale

Building a custom weighing system doesn't have to be a frustrating electronics puzzle. The SparkFun OpenScale is a straightforward, open-source solution that removes the complexity of measuring weight (even when temperature is taken into account). By combining a microcontroller, a precision ADC, and USB-to-serial conversion on a single board, the OpenScale lets you turn any standard four- or five-wire load cell (or four load sensors in a Wheatstone bridge) into a fully functional DIY scale.

Plug-and-Play Precision

Getting accurate mass readings is as easy as plugging in a cable. Powered by an onboard ATmega328P microcontroller, the OpenScale is ready to work right out of the box.

• Instant Data: Simply attach your load cell, plug the board into your computer's USB port (you'll need a USB cable terminated with a Mini-B connector), and open a terminal window at 9,600bps. You will immediately begin seeing live mass readings.
• Simple Configuration: An easy-to-navigate serial menu lets you quickly adjust your calibration values, sample rates, timestamps, and precision units without reflash.
• High-Resolution ADC: The onboard HX711 acts as a 24-bit Analogue-to-Digital Converter, ensuring your weight readings are incredibly precise.

Designed for Long-Term Use

The OpenScale was purpose-built for continuous, long-term applications that require constant readings without user intervention. An equipped OpenScale can remain in place for months at a time, reliably transferring data directly to your serial terminal or to an attached data logger, such as the SparkFun OpenLog.

Because physical load cells can drift slightly with changes in weather, we included an onboard TMP102 sensor to log ambient temperature alongside your weight data.

• Schematic
• Eagle Files
• Hookup Guide
• Datasheets
  • HX711
  • TMP102
• Arduino Library
• Particle Sketch
• GitHub