The SparkFun Qwiic Scale is a small breakout board for the NAU7802 that allows you to easily read load cells to accurately measure the weight of an object. By connecting the board to your microcontroller you will be able to read the changes in the resistance of a load cell and, with some calibration, you'll be able to get very accurate weight measurements. This can be handy for creating your own industrial scale, process control or simple presence detection. Utilizing our handy Qwiic system, no soldering is required to connect it to the rest of your system. However, we still have broken out 0.1"-spaced pins in case you prefer to use a breadboard.
By connecting a load cell to the Qwiic Scale you will be able to translate sensor data into something your microcontroller can read. The NAU7802 is an ADC with built in gain and I2C output to amplify and convert the readings from a standard load cell. A load cell is basically a device that translates pressure or force into electrical signals. In most cases this signal is very small and needs to be amplified. There are many popular chips that read the change and amplify it, but the NAU7802 goes one step further and converts everything to a true I2C output (attached to a Qwiic connector).
The board provides a four spring terminal to connect your load cell with no soldering required. In addition to the I2C pins, the board also breaks out an interrupt pin and AVDD to the edge of the board. The differential input signals (plus a second set of input signals) are broken out to the middle of the board, as well.
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. If you need to use more than one NAU7802 sensor consider using the Qwiic Mux Breakout.
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!
If a board needs code or communicates somehow, you're going to need to know how to program or interface with it. The programming skill is all about communication and code.
Skill Level: Competent - The toolchain for programming is a bit more complex and will examples may not be explicitly provided for you. You will be required to have a fundamental knowledge of programming and be required to provide your own code. You may need to modify existing libraries or code to work with your specific hardware. Sensor and hardware interfaces will be SPI or I2C.
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If it requires power, you need to know how much, what all the pins do, and how to hook it up. You may need to reference datasheets, schematics, and know the ins and outs of electronics.
Skill Level: Rookie - You may be required to know a bit more about the component, such as orientation, or how to hook it up, in addition to power requirements. You will need to understand polarized components.
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Based on 5 ratings:
My only regret was I didn't use a teensy 4.0 to take full advantage of the speed.
I'm using this with an ESP32-S2 via the Qwiic connector, running in C++/Arduino. The library is easy to use, although I've only gotten to sampling the sensor (not zeroed or tared). It's really fast, too.
My only dislike is the large spring terminal block. Since I'm retrofitting a scale for wireless use, it takes up A LOT of space for the minor benefit of plugging wires in (which ideally you won't be doing very often). I soldered a 7 pin screw terminal block to the bottom and clipped off the end of the board past it. Much nicer and tucks into my scale.
This device works as advertised, but it did take more time to configure than I expected. This was due to the lack of documentation about the labeled thru-holes on the left side of the PC board. These holes are strangely not included on the printed schematic.
I think the designers are mostly targeting Arduino users, and for that case, the documentation seems fine. In my case, I was using a Zilog chip with my own code / libraries for I2C. In any case, I strongly recommend this product. It is well designed and an excellent value!
I was using an HX711 Load Cell Amplifier in a project but was getting inconsistent values and it was subject to interference. Finally got one of these and used their suggested libraries and the project started working as designed. Highly recommended.
The project also used a Zio Qwiic OLED Display so connecting the two was very easy and I believe the Qwiic cabling eliminated the source of the interference.