HX711 WEIGHT / LOAD CELL 2 CHANNEL PRESSURE SENSOR AMPLIFIER MODULE
The Envistia Mall HX-711 Load Cell Amplifier is a low-cost A/D converter module incorporating a very high precision 24 bit ADC and differential high gain inputs that allow you to easily read load cells, bridge sensors, pressure, strain, and weight sensors 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 used to create your own weight scale, process control, or simple presence detection.
Based on Avia Semiconductor’s patented technology, HX711 is a precision 24-bit analog-to-digital converter (ADC) designed for weigh scales and industrial control applications to interface directly with a bridge sensor. The input multiplexer selects either Channel A or B differential input to the low-noise programmable gain amplifier (PGA). Channel A can be programmed with a gain of 128 or 64, corresponding to a full-scale differential input voltage of ±20mV or ±40mV respectively, when a 5V supply is connected to VCC analog power supply pin. Channel B has a fixed gain of 32. An on-chip power supply regulator eliminates the need for an external supply regulator to provide analog power for the ADC and the sensor. There is no programming needed for the internal registers. All controls to the HX711 are through the pins.
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.
Load cells use a four-wire Wheatstone bridge 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+)
- Green (Amplifier -)
- Yellow (Shield)
HX711 Features & Specifications:
- Two selectable differential input channels
- On-chip active low noise PGA with selectable gain of 32, 64 and 128
- On-chip power supply regulator for load-cell and ADC analog power supply
- On-chip oscillator requiring no external component with optional external crystal
- On-chip power-on reset
- Simple digital control and serial interface: pin-driven controls, no programming needed
- Simultaneous 50 and 60Hz supply rejection
- Current consumption including on-chip analog power supply regulator: normal operation < 1.5mA, power down < 1uA
- Operation supply voltage range: 2.6V ~ 5.5V
- Operation temperature range: -40 ~ +85oC
- Dimensions: 34mm x 21mm x 3mm (1.34in x 0.8in x 0.12in) L x W x H
HX711 Simplified Schematic:
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