Our RedBoards are great. But don't they sometimes seem a little BIG?!
Enter smôl, a new range of boards which are both small in size and small on current draw. It's a smôl world!
The smôl Scale is a smôl-format 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, presence detection or bee hive weight monitoring and logging system!
By connecting a load cell to the smôl 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 NAU78023's INTerrupt pin can be connected to the smôl bus via configurable jumpers.
The smôl scale includes both breakout pads and a 4-pin JST connector for the load cell connections. The 4-pin connector is the same size as our standard Qwiic connectors, meaning that you can use one of our standard Qwiic cables to help with the connections. See the hook-up accessories listed below for the product IDs. Here are the standard cable colors:
| Signal | Qwiic Cable Color | Load Cell Color |
|---|---|---|
| E- (GND) | Black | Black |
| E+ (3.3V) | Red | Red |
| A+ | Blue | Green or Blue |
| A- | Yellow | White |
smôl is an ecosystem of miniature processor boards, peripheral boards, power boards and accessories. Designed to be both physically small and to have the smallest possible current draw, smôl is the perfect choice for applications like wildlife tracking or discrete long-term monitoring. smôl boards are designed to stack one on top of the other, using 16-way 0.5mm-pitch Flexible Printed Circuits (FPCs) to provide the interconnect from one board to the next. Looking for a really compact solution for your next project? This is it!
We will be adding new smôl boards over the coming months. Don't see the board you need for your application? Reach out to us via the SparkX Forum and tell us which board(s) we should add next!
Features:
NAU7802 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
smôl Specifics:
- Interface: I2C
- I2C Address: 0x2A (unshifted)
- Configurable INT jumpers
- INT can be connected to smôl GPIO if required (disabled by default)
Properties:
- Length: 1.60" (40.6mm)
- Width: 0.42" (10.7mm)
- Height: 0.19" (4.7mm) max.
- Weight: 1.2g (0.04oz)
- PCB thickness: 0.8mm
Documents:
smôl Dynamic NFC/RFID Tag Documentation:
- Schematic
- Eagle Files
- Datasheet (NAU7802)
- Getting Started with Load Cells
- GitHub Hardware Repo
- SparkFun Qwiic Scale NAU7802 Arduino Library
smôl Documentation:
Standard cable colors:
| Signal | Qwiic Cable Color | Load Cell Color |
|---|---|---|
| E- (GND) | Black | Black |
| E+ (3.3V) | Red | Red |
| A+ | Blue | Green or Blue |
| A- | Yellow | White |
