SparkFun Qwiic Scale - NAU7802

The SparkFun Qwiic Scale is a compact breakout board for the NAU7802 that enables easy reading of load cells to accurately measure the weight of objects. This board connects to your microcontroller, allowing you to read changes in the resistance of a load cell and, with some calibration, get very accurate weight measurements. This makes it ideal for creating your own industrial scale, process control or simple presence detection. It uses the Qwiic system, eliminating the need for soldering when connecting it to your system. However, 2.54mm-spaced pins are also available for those who prefer using a breadboard.

Once a load cell is connected to the Qwiic Scale, sensor data can be translated into something your microcontroller can read. The NAU7802 is an ADC (Analog to Digital Converter) with built-in gain and I²C output to amplify and convert the readings from a standard load cell. Load cells are devices that translate pressure or force into electrical signals. These signals are typically very small and need to be amplified. The NAU7802 goes a step further by converting everything to a true I²C output, which is attached to a Qwiic connector.

The board provides a four spring terminal to connect your load cell without any need for soldering. Besides the I²C pins, the board also breaks out an interrupt pin and AVDD to the edge of the board. The differential input signals, along with a second set of input signals, are broken out to the middle of the board.

Note: The I²C address of the NAU7802 is 0x2A and is hardware defined. A multiplexer/Mux is required to communicate to multiple NAU7802 sensors on a single bus.

The SparkFun Qwiic connect system is an ecosystem of I²C sensors, actuators, shields and cables that make prototyping faster and less prone to error. All Qwiic-enabled boards use a common 1mm pitch, 4-pin JST connector. This reduces the amount of required PCB space, and polarized connections mean you can’t hook it up wrong.

The NAU7802 Qwiic Scale can also be automatically detected, scanned, configured, and logged using the OpenLog Artemis datalogger system. No programming, soldering, or setup required!

Features:

• Operating Voltage: 3.3V (NAU7802: 2.7V-5.5V)
• 24-bit Dual-Channel Analog to Digital Converter
• Programmable Gain Amplifier
• On-chip temperature sensor
• Simultaneous 50Hz and 60Hz rejection
• Programmable PGA gains from 1 to 128
• Programmable aDC data output rates
• External differential reference voltage range from 0.1V to 5V
• Low Power Consumption and Programmable Power Management Options
  • <1uA standby current
• 2x Qwiic Connectors

Documents:

• Schematic
• EagleFiles
• Hookup Guide
• Datasheet (NAU7802)
• Getting Started with Load Cells
• SparkFun Qwiic Scale NAU7802 Arduino Library
• Hardware Repo