HX711 Load Cell Amplifier Board ADC Converter Weight Module

Specifications

• ADC Resolution: 24-Bit High-Precision
• Operating Voltage: 2.6V to 5.5V DC
• Operating Current: < 1.5mA (Normal), < 1uA (Power Down/Sleep)
• Input Channels: Two selectable differential input channels (Channel A and Channel B)
• Programmable Gain Amplifier (PGA): Active low noise PGA with selectable gain of 32, 64, and 128
• Data Rate: Selectable 10 SPS (Samples Per Second) or 80 SPS
• Excitation Voltage: On-chip power supply regulator for load-cell and ADC analog power supply
• Interface: Simple 2-wire serial interface (Clock and Data)
• Oscillator: On-chip oscillator requiring no external component (optional external crystal supported)
• Dimensions: ~ 24mm x 16mm

Applications

• Smart Retail: Building custom Point-of-Sale (POS) weighing scales or inventory management bins.
• Industrial Automation: Force measurement testing, material sorting, and automated batching systems.
• IoT Health Devices: Smart beds that track weight/movement, or WiFi-enabled body weight scales.
• Agriculture: Silo weight tracking, beehive monitoring for honey production.
• Popular Projects: Smart coffee tampers, thrust-measurement stands for model rockets, and automated pet feeders.

Unlock New Capabilities

• Past Projects: If you've been using simple Force Sensitive Resistors (FSRs) to detect basic "touch" or "squeeze" pressure...
• The Upgrade: This HX711 module unlocks true, calibrated high-precision weight tracking. You can move from simply knowing if something is pressing down, to knowing exactly how many grams it weighs.
• Effort Level: Intermediate. Requires basic soldering for the header pins and an understanding of calibrating sensors via code.
• Hardware Required: An Arduino/ESP32, a Beam or Button Load Cell, and standard jumper wires.

Virtual Technician & Wiring Guide

• ⚠️ Voltage Warning: The HX711 is highly versatile and works safely with both 3.3V and 5V microcontrollers. Ensure you supply the VCC that matches your microcontroller's logic level (e.g., 3.3V for ESP32/Raspberry Pi, 5V for Arduino Uno) for optimal logic communication.

Connecting to Microcontroller (Right Side Pins):

• VCC: Connect to 5V or 3.3V (Matches Microcontroller Logic)
• GND: Connect to System Ground
• DT (Data): Connect to Digital Pin (e.g., D2 on Arduino)
• SCK (Clock): Connect to Digital Pin (e.g., D3 on Arduino)

Connecting to a Standard 4-Wire Load Cell (Left Side Pins):

• E+ (Excitation Plus): RED Wire
• E- (Excitation Minus): BLACK Wire
• A- (Signal Minus): WHITE Wire
• A+ (Signal Plus): GREEN Wire (Note: Wiring colors can occasionally vary by load cell manufacturer. Always check your load cell's datasheet if readings are inverted).

Package Includes: 

• 1 x  HX711 Load Cell Amplifier Board ADC Converter Weight Module

Frequently Asked Questions (FAQ)

• What is the HX711 module used for?
  It is a 24-bit analog-to-digital converter designed to amplify the tiny electrical signals from a load cell (weight sensor) so a microcontroller can read them as accurate weight measurements.
• How do I connect a 4-wire load cell to the HX711?
  Connect Red to E+, Black to E-, White to A-, and Green to A+. If your load cell pushes negative values when weight is added, swap the White and Green wires.
• What do the wire colors on a standard load cell mean?
  Red and Black provide the excitation voltage (powering the strain gauge). White and Green are the signal wires that return the tiny voltage changes back to the amplifier.
• Can I use the HX711 with a 3.3V microcontroller like the ESP32?
  Yes. The HX711 supports a working voltage of 2.6V to 5.5V. Power the VCC pin with 3.3V to ensure the data logic signals match your ESP32 safely.
• What is the difference between Channel A and Channel B on the HX711?
  Channel A can be programmed with a gain of 128 or 64, providing the highest precision for standard load cells. Channel B has a fixed gain of 32 and is typically used for system parameter monitoring or a secondary, less precise sensor.
• Why are my HX711 weight readings fluctuating randomly?
  Fluctuations are usually caused by a noisy power supply, loose breadboard connections, or lack of shielding. Ensure you are using a clean power source and keep the load cell wires as short as possible.
• How do I calibrate the HX711 with an Arduino?
  Use a calibration sketch (found in the HX711 library examples). Place a known weight on your scale, run the code, and adjust the calibration factor variable until the serial monitor outputs the exact known weight.
• What is the maximum weight the HX711 can measure?
  The HX711 itself does not have a weight limit; it only reads voltage. The maximum weight depends entirely on the physical load cell you connect to it (e.g., 1kg, 50kg, or 1000kg).
• Does the HX711 use I2C or SPI communication?
  No. It uses a custom two-wire serial protocol (Data and Clock pins). It does not use standard I2C or hardware SPI, which is why a specific HX711 software library is required.
• How can I connect multiple HX711 modules to one Arduino?
  You can connect multiple modules by assigning a unique DT (Data) pin for each HX711. They can all share a single SCK (Clock) pin, or use separate clock pins depending on your code setup.
• What is the difference between 10 SPS and 80 SPS on the HX711?
  SPS stands for Samples Per Second. 10 SPS is slower but provides highly stable, noise-free readings. 80 SPS is faster (useful for impact or dynamic weight testing) but may introduce more signal noise.
• How do I change the data rate to 80 SPS?
  The module is hardwired to 10 SPS by default. To switch to 80 SPS, you must cut the trace connecting the "RATE" pin to ground on the PCB and solder it to VCC (or bridge the designated RATE solder pads on the back, depending on the board revision).
• Why is my HX711 returning 0 or -1 consistently?
  This usually indicates a communication failure. Check that your DT and SCK pins are defined correctly in your code and that your jumper wires are not faulty.
• Can I use the HX711 with a Raspberry Pi?
  Yes, Python libraries are available for the HX711 on Raspberry Pi. Ensure you power the HX711 with 3.3V to protect the Pi's GPIO pins.
• Does the HX711 require an external amplifier?
  No. The HX711 chip has a built-in Programmable Gain Amplifier (PGA), making an external amplifier unnecessary.
• How do I put the HX711 into sleep mode to save power?
  In your code, pull the SCK (Clock) pin HIGH for more than 60 microseconds. The chip will enter power-down mode. Pull it LOW to wake it up.
• Can I use a 5-wire load cell with this module?
  Yes. A 5-wire load cell is the same as a 4-wire, but the extra wire (usually yellow or thick black) is a shield wire. Connect the shield wire to the ground (GND) to reduce electromagnetic interference.
• What is the purpose of the E+ and E- pins?
  E+ and E- supply a highly stable "Excitation" voltage directly from the HX711's internal regulator to power the load cell's internal wheatstone bridge circuit.