A load cell or a Strain Gauge is essentially a transducer that produces an electrical signal whose magnitude is proportional to the force applied. We can use the load cells or Strain gauges in different automation projects. We can use the load cells for the precise weight measurement if properly get calibrated. Commonly used in industrial processes where the weight of certain products is measured. We can also use the load cells in infinitely different ways, for example, for automatic bag-filling machines.
An Overview of the HX711 Sensor
HX711 Weighing Sensor Module has an HX711 chip, which is a high precision Analog to digital converter. It has two analog input channels and we can get higher gain by programming these channels. In short, the HX711 module strengthens the low electric output of Load cells, and then this amplified output & digitally converted signal are given into the microcontroller to drive the weight.
Features and Specifications of HX711
Features
- With metal shielding and strong anti-interference, and obligate MCU (STC15F104) position, can upgrade secondary development.
- Two ways can choose differential input
- The chip low noise programmable amplifier, optional gain to 32, 64 and 128
- The chip voltage stabilizing circuit can be directed to the external sensors and chips inside the A/D converter to provide a power supply
- Automatic reset circuit
- Simple digital control and serial interface communication are all controlled by input pin, and chip register without programming
- Can choose 10 Hz or the output data rate of 80 Hz
- Synchronization of 50 Hz or 60 Hz power supply interference suppression
Specifications
- Typical working current: < 1.7 mA, power current: < 1 mu A
- Working voltage range: 2.6 ~ 5.5 V
- Low operating temperature range: – 20 ~ + 85 ℃
- Module working voltage: 4.8V to 5.5V
- Size: 29*17*4mm
Pinouts
| Pin Name | Description |
| VIN | Module power supply – 3.3-5 V |
| GND | Ground |
| SCK | (Serial Clock) Module and microcontroller synchronization |
| OUT | Module digital output |
| E+ | Load cell power supply |
| E- | Load cell Ground |
| A+ | The first output of the first cell |
| A- | A second output of the first cell |
| B+ | The first output of the second cell |
| B- | A second output of the second cell |
Applications
Weighing Scale
One of the most common circuits with the HX711 and Load Cell is its absolute use to make a weighing scale interfaced with the microcontroller. Through this project, one can learn how to make a small weighing scale.
Punching Bag Project
Apart from measuring weights, this strain gauge or load cell can also be utilized as a force gauge to measure force in newtons. Through this project, one can learn how to measure first power using an HX711 with any microcontroller.
