Product Overview
Building a custom, high-accuracy scale shouldn't require writing complex code from scratch. The SparkFun OpenScale IoT takes the hassle out of measuring weight and temperature with an easy-to-use, wireless solution built around the powerful ESP32-PICO-MINI. This updated version of the original SparkFun OpenScale supports multiple load cell types and lets users access the device via multiple interfaces of their choosing. That means, regardless of whether you are monitoring the static load of a beehive over several months or need to precisely weigh the right amount of beans for the perfect cup of coffee, this board turns any standard load cell into a fully functional, wirelessly connected weighing system.
Flexible Connectivity & Setup
Getting your OpenScale up and running is incredibly simple. Just attach any four or five-wire load cell, and you'll be able to configure your calibration, sample rates, and precision through a straightforward terminal menu. This enables you to turn a load cell or four load sensors, arranged in a Wheatstone bridge configuration, into a DIY weigh scale for whatever the application.
- Bluetooth & Wired Config: Connect via Bluetooth/BLE or a wired USB-C/serial connection to access the terminal menu at 115,200bps. (Note: Terminal configuration via Bluetooth is not supported on Apple devices.)
- WiFi Integration: Connect the board to your local 2.4GHz WiFi network to view your live data and perform Over-The-Air (OTA) firmware updates.
- Qwiic Expansion: Easily add additional I2C sensors and displays to your project using the integrated Qwiic connector. No soldering required!
Connecting the OpenScale IoT to a Bluetooth host device requires a terminal application installed on it; if you're connecting it to a phone or other mobile device, make sure to install a terminal application of your choice. However, if connecting to this OpenScale wirelessly isn't quite your style, you can still interface with it via a wired serial connection over USB-C or serial port.
Precision & Long-Term Use
To ensure you get the most accurate data possible, the OpenScale - IoT combines multiple sensing technologies into a single footprint. The onboard HX711 acts as a 24-bit ADC when, let’s say, you attach four individual strain gauges to read your Wheatstone bridge using a combinator with high precision.
The OpenScale design is intended for projects and applications where the load is static or where constant readings are needed without user intervention (for example, on a conveyor belt system). A load cell equipped with an OpenScale IoT can remain in place for months without user interaction! Because physical load cells can drift slightly with environmental changes, the board also features an integrated TMP102 sensor to log ambient temperature. We even added a 3-pin screw terminal to attach an external temperature probe using the one-wire interface directly at the measurement site!
Features & Specs
- ESP32-PICO-MINI Module
- 2.4GHz WiFi, Bluetooth®, and Bluetooth LE supported
- On-Chip PCB antenna
- Serial configuration menu supported over wired and Bluetooth connections
- Over-the-Air (OTA) firmware updates with WiFi connection
- Operating Voltage: 5V
- Operating Amperage: 80-100mA
- Power Cycling above 500ms
- Selectable 10SPS or 80SPS Output Data Rate
- On Board & External Temperature Sensors
- Fixed & Adjustable Gain
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Documentation
- Schematic
- KiCad Files
- Board Dimensions
- Hookup Guide
- Datasheets:
- OpenScale - IoT Firmware Binaries
- GitHub Repository
