Hx711 electronic scale sensor module

Types

The HX711 electronic scale sensor module is one of several types of weight sensor modules available on the market; it is actually highly specialized for digital measurements. Here is a classification of electronic weight sensor types based on the mechanism of weight measurement.

Strain Gauge-based Sensors

The operation of these sensors is based on the application of strain gauges. Strain gauges are fixed to a deformation body, which deforms slightly under load. They are the most popular sensors used in load cell scales because they can combine accuracy and practicality.

Load Cells

Load cells are transducers that convert a force into an electrical signal. OIML approved Load cells also employ strain gauge technology and are typically encapsulated inside metal frameworks for safety and stability in extreme conditions.

Capacitive Sensors

These sensors measure weight by assessing changes in capacitance caused by alterations in the distance between two conductive plates. People prefer them for lightweight applications and dynamic environments such as food packaging and textiles since they don't have moving parts and can give reliable results.

Piezoelectric Sensors

These sensors exploit the piezoelectric effect of certain materials to give electrical charges proportional to the applied mechanical force. They are often used for real-time weight measurements in industrial applications because they respond quickly to changes in loads.

Magnetic Sensors

These sensors measure weight by exploiting the force needed to levitate a magnet, also called magnetic suspension. This non-contact method is typically used for fragile items since it doesn't touch the load at any point.

While each type has a unique way of operating, in the case of practical use, strain gauge-based and capacitive sensors are the most common due to their versatility and efficiency.

Industry Applications

HX711 modules offer accurate digital weight measurements and are ideal for many professional uses in various industries. Below are specific uses of the module in different contexts.

Healthcare

In healthcare facilities, the module works with weight measuring scales and patient beds that give weight readings and monitor patient's health status with a high level of accuracy. The digital output of the HX711 is compatible with the requirement of data logging in healthcare for analysis and monitoring.

Agriculture

Common uses of the HX711 include animal feeding scales, grain weighing systems, and irrigation control in smart farming practices. The precision of the module helps farmers determine and adjust feed amounts, track crop yields, and optimize resource allocation.

Logistics and Freight

In the freight transportation business, the module is used in truck scales and pallet jacks to measure weight for cargo optimization and compliance with weight limits. The digital conversion of this module makes weight data manipulation easy, which helps reduce overloading and enhance safe transport.

Culinary and Food Industry

The food preparation industry relies on this electronic scale sensor module to offer precise measurements of ingredients, portion control scales, and nutritional analysis. Accurate weighing improves recipe consistency and reduces waste, a key benefit to restaurants and food manufacturers.

Manufacturing and Quality Control

For manufacturing, the module is incorporated into quality control scales, packaging systems, and inventory management. It helps in achievement of measurement precision during component weighing, which supports process efficiency while reducing defects.

Product Features

The HX711 is a breakout board that is just a chip and a two-terminal screw connector for strain gauges used to measure very small forces. It's a 24-bit analog-to-digital converter (ADC) designed specifically for weighing scales and similar applications. Let's have a detailed look at the various features of the H711 sensor module.

High Precision

The 24-bit resolution of the module enables it to give fine measurements of weight, even the smallest, which makes it quite suitable for uses in industries that need accuracy.

Dual-Channel Input

The availability of two signal input channels means that the module can process signals from any two strain gauges simultaneously. The scales can thus be balanced, improved accuracy and error correction achieved.

Works with Low volt Batteries

The module uses low power since it operates at 5V and gives high output even on low input voltage, making it ideal for battery-operated devices.

Internal Programmable Gain Amplifiers

The gain of the amplifiers can be set to 1, 2, 64, or 128. This enables flexibility to work in various load cell configurations so as to achieve optimal sensitivity depending on the specific sensor application.

Simplified Connections

With the integrated circuit and hardware, the sensor's connections are simplified in the HX711 design for easy and direct connections of load cells and the microcontrollers, usually resulting in faster and easier prototypes.

Product Specifications

Key Features

• Type: Load cell interface, 24-bit ADC
• Resolution: 24-bit
• Channels: 2
• Power Supply: 2.7V-5V
• Output: Digital (serial)
• Operating Temperature: -10°C to 50°C

How to Install

Following is a step-by-step guide for installing an HX711 electronic scale sensor module, whether for weight measurement or creating a digital scale.

• Gather the required tools: An Arduino or Raspberry Pi, a strain gauge or load cell, the HX711 module, connecting wires, and a breadboard or soldering materials if required.
• Make the connections: Connect the four wires of the load cell to the HX711 module. The red wire should connect to E+, the black wire to E-, the white wire to S+, and the green wire to S- grid. Then connect the HX711 to the Arduino/Pi by connecting VCC to 5V, GND to the ground, DT to digital pin 3, and SCK to digital pin 2.
• Upload the code: Find a library online, such as the "HX711" library for Arduino. After installing it, upload the example code to calibrate and test the scale to see if the setup is right.
• Calibration: follow the on-screen instructions to calibrate the scale by weighing known objects so that it can be set to give correct measurements in the case of weight.
• Putting it together: The load cell can be fixed to a platform for practical use, and the HX711 can be placed in a protective casing to avoid any damage to the module.

Maintenance

• Software maintenance: Periodically update the software that runs the module to correct bugs. Also, use updated libraries to improve functionality and support calibration for accuracy.
• Calibration checks: Routine calibration is necessary for weighing scales to maintain accuracy over time. Basic accuracy tests should be performed, and recalibration should be based on weight reference standards when inaccuracies are found.
• Hardware checks: Regularly inspect the wiring and connection of the HX711 and strain gauge for signs of wear, corrosion, or damage. Tighten loose connections and replace any worn-out parts.
• Environmental protection: If operating the module in harsh conditions, enclose it in a suitable protective casing. It is also recommended to use environmental seals for dust, moisture, or extreme temperature exposure.
• Power management: Check the power supply for ads, ensure consistent voltage delivery to the module for stable operation. Monitor the battery status if operating on battery power to avoid fluctuations due to low battery.

Quality & Safety

The HX711 module, just like any other electronic equipment for weight measuring devices, must comply with certain quality and safety rules to guarantee performance sufficiently, safety, and certification of the product. Below are the ways this concern can be addressed.

Quality Control

• Use of Authorized Manufacturers: This authorized IC card is produced only by a few manufacturers who have the resources to produce high-quality products and the know-how of the set specifications for the needed materials.
• Testing: The modules are tested at the time of production to fix defects before they are sold. They perform tests on the sensors to evaluate accuracy, sensitivity, and stability.
• Calibration: A strain gauge load cell is calibrated through series evaluation to measure any error and fix it before it goes out for use. It improves accuracy and ensures proper functioning.

Safety Standards

• Electrical Safety: The electrical components of the module have to be designed in such a way as to avoid short-circuiting, excessive leakage, or any other electrical hazard. That means there is over current protection and proper insulation.
• Operational Safety: Any operational hazard that might arise when using the module, such as incorrect readings leading to unsafe loads, has to be eliminated through proper training and understanding of the module's operation.
• Chemical Safety: If the module is treated with chemicals, appropriate casings should be used for the protection of the internal components from harm. Apply proper disposal techniques to prevent chemical exposure.

Regulatory Compliance

• Certification Standards: Certification standards like OIML rules are set for legal measuring instruments of which load cells are part. The certification of the modules means they comply with international precision and performance requirements.
• Compliance Testing: Modules are evaluated for electrical emission and safety evaluations and environmental worries like RoHS or WEEE to confirm they meet legal requirements.

Q&A

Q1: What is the function of the HX711?

A1: The module gives digital values that are proportional to weight by converting small voltages from load cells into digital values, which can be read easily by a microcontroller.

Q2: What is the weight/load that an HX711 can handle?

A2: The module itself does not have a load-handing capacity, but the capacity depends on the load cell or strain gauge used in combination with the module.

Q3: Is there any difference between ADC and the example of a digital scale?

A3: Although both involve reading of values, an ADC is concerned with continuous analog signals, and a digital scale is about measurement through digital conversion of analog signals by the help of ADC.

Q4: Is the HX711 water resistant?

A4: The module is not water-resistant on its own, but after proper encapsulation of the circuitry protective housing against moisture and water, it becomes water-resistant.

Q5: What do I need to do to get accurate readings from the HX711?

A5: To obtain the correct readings, there should be proper calibration of the module and elimination of environmental noise, the application of a stable power source, and the assurance that the load cell and strain gauge are properly balanced and working.