SparkFun
SparkFun Load Cell Amplifier - HX711
The SparkFun Load Cell Amplifier is a small breakout board for the HX711 IC that allows you to easily read load cells to measure weight. By connecting the am...
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The SparkFun Load Cell Amplifier is a small breakout board for the HX711 IC that allows you to easily read load cells to measure weight. By connecting the amplifier to your microcontroller you will be able to read the changes in the resistance of the 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.
This version of the SparkFun Load Cell Amplifier features a few changes that you specifically asked for! We have separated the analog and digital supply, as well as added a 3.3uH inductor and a 0.1uF filter capacitor for digital supply.
The HX711 uses a two-wire interface (Clock and Data) for communication. Any microcontroller’s GPIO pins should work, and numerous libraries have been written, making it easy to read data from the HX711. Check the hookup guide below for more information.
Load cells use a four-wire Wheatstone bridge configuration to connect to the HX711. These are commonly colored RED, BLK, WHT, GRN and YLW. Each color corresponds to the conventional color coding of load cells:
- Red (Excitation+ or VCC)
- Black (Excitation- or GND)
- White (Amplifier+, Signal+ or Output+)
- Green (A-, S- or O-)
- Yellow (Shield)
The YLW pin acts as an optional input that is not hooked up to the strain gauge but is utilized to ground and shield against outside EMI (electromagnetic interference). Please keep in mind that some load cells might have slight variations in color coding.
Note: Special thanks to Bodge for supplying the Library for the HX711!
Jargon buster
Plain-language definitions for the technical terms used above.
- breakout
- A breakout board carries a small or fine-pitched component and brings its connections out to standard, breadboard- and header-friendly pins. Describing a part as a breakout means it can be wired into a project without soldering directly to the component's tiny contacts.
- electromagnetic interference
- Electromagnetic interference (EMI) is unwanted electrical noise from nearby devices, cables, or radio signals that can disturb the signals carried in a wire or circuit. Shielding helps reduce this noise, which matters because cleaner signals make data and communication links less prone to errors and dropouts.
- GND
- GND is the ground or reference connection (0 V) for a circuit. When connecting two devices together, their grounds must be joined so both agree on what counts as a low or high signal.
- GPIO
- General-purpose input/output pins are microcontroller pins you can set in software to read signals, switch devices on and off, or connect to peripherals. The number of GPIO pins matters because it limits how many buttons, LEDs, sensors, and other parts you can wire directly to the board.
- microcontroller
- A microcontroller is a small computer on a single chip that runs a stored program and controls connected inputs and outputs such as buttons, sensors, displays and communication interfaces. In a device built around one, it is the part that executes the code and coordinates the device's behaviour.
- Shield
- An add-on board that plugs into a main controller board to give it extra features such as sensing, motor control or communication. Knowing a product supports shields helps you judge whether it can connect neatly into an existing maker-board setup.
- Strain gauge
- A strain gauge is a sensor element whose electrical resistance changes when it is stretched or compressed. It is commonly used to measure force, weight, pressure or bending, and because its resistance change is small it usually needs precise differential measurement electronics such as a high-resolution ADC.
- VCC
- VCC is the positive power-supply connection on a chip or module. Connecting it to the correct supply voltage is needed for the part to power on and helps avoid damaging the electronics.
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Sensors & Input
SparkFun HX711 Load Cell Amplifier Schematic
Schematic · 58.6 KB · Click any page to view full size
HX711 Datasheet
Datasheet · 263.2 KB · Click any page to view full size
Supplier page — sparkfun.com
Supplier Description · 1.2 MB · Click any page to view full size
Resources & Downloads
Guides, code examples, and more
Source Code
Open-source libraries, firmware & example projects for this product
A breakout board for the HX711 load cell weight measuring amplifier
38228f8
about 7 years ago
· 27 commits
- datasheets Updated Schematic and Datasheet about 7 years ago
- firmware Fix examples to match rev on HX711 library about 7 years ago
- hardware Updated Schematic and Datasheet about 7 years ago
- Production created panel v11 about 10 years ago
- .gitattributes :space_invader: Added .gitattributes & .gitignore files over 11 years ago
- .gitignore Hardware is ready for protos. over 11 years ago
- readme.md Update readme.md over 7 years ago
An Arduino library to interface the Avia Semiconductor HX711 24-Bit Analog-to-Digital Converter (ADC) for Weight Scales.
be5e3d2
over 4 years ago
· 105 commits
- doc Add faq.md over 5 years ago
- examples Simplify pinout definitions by not trying over 7 years ago
- src Fixed gpio not configured as pullup for non espressif boards. over 4 years ago
- .gitignore Add "plaformio.ini" and build environment tooling for compiling the "HX711_basic_example" against platforms atmelavr, espressif8266, over 7 years ago
- .travis.yml Add "plaformio.ini" and build environment tooling for compiling the "HX711_basic_example" against platforms atmelavr, espressif8266, over 7 years ago
- CMakeLists.txt Add CMakeLists.txt for Arduino as a ESP-IDF component. over 4 years ago
- CONTRIBUTORS.md Extend hardware support notes in README over 7 years ago
- keywords.txt added keywords.txt almost 8 years ago
- library.json Update version number to 0.7.5 over 4 years ago
- library.properties Update version number to 0.7.5 over 4 years ago
- LICENSE Update LICENSE over 7 years ago
- Makefile Update Makefile to use Python 3 over 5 years ago
- platformio.ini Update version number to 0.7.5 over 4 years ago
- README.md Link the FAQ file into README.md over 5 years ago
Related Tutorials
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