Load Cell Amplifier - HX711 (SEN-13879)

Load Cell Amplifier - HX711

Sparkfun SEN-13879

This 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 board is perfect if you want to create your own industrial scale, process control, or simple presence detection.

The analog and digital supplies are routed separately and there is a 3.3uH inductor and a 0.1uF filter capacitor added to the digital supply for filtering.

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 Wheat-stone bridge configuration to connect to the HX711. These are commonly coloured Red, Black, White, Green, and Yellow. Each colour 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 Yellow pin acts as an optional input that is not hooked up to the strain gauge but is utilized to ground and shield against outside electromagnetic interference (EMI). Please keep in mind that some load cells might have slight variations in colour coding.

Load Cell Amplifier Features:

• Operation Voltage: 2.7 ~ 5V
• Operation Current: < 1.5mA
• Selectable 10SPS or 80SPS output data rate
• Simultaneous 50 and 60Hz supply rejection

Load Cell Amplifier Schematic:

Don't forget the!:

The HX711 load cell amplifier is used to get measurable data out from a load cell and strain gauge.
To use this board, you'll need to get hold of a Strain Gauge based Load Cell or alternatively using 4 x Load Sensors and a Combinator Board. This combinator board makes it easy to turn your four load sensors into a wheat-stone bridge type load cell.