The HX711 is a precision 24-bit analog-to-digital converter (ADC) designed specifically for weigh scales and industrial control applications. It features a built-in low-noise amplifier and a programmable gain, making it ideal for interfacing with load cells and other sensors requiring high accuracy and stability. The HX711 simplifies the process of converting small analog signals into digital data, enabling precise measurements in a wide range of applications.
This circuit integrates multiple HX711 weighing sensor modules connected to load cells for weight measurement, an OV7725 camera module interfaced with a Raspberry Pi 4B for image capture, and a WeMOS ESP8266 for wireless communication. Additionally, it includes an Adafruit 24-Channel PWM LED driver for controlling LEDs and a buzzer module for audio alerts.
Open Project in Cirkit Designer
This circuit is a weighing system that uses two load cells connected to HX711 modules for weight measurement, interfaced with an Arduino Mega 2560. The system includes an LCD for displaying weight, a Bluetooth module for wireless communication, and LEDs for status indication, with a micro servo for additional mechanical control.
Open Project in Cirkit Designer
This circuit is a multi-sensor data acquisition system powered by a 18650 battery and managed by an ESP8266 microcontroller. It includes a load sensor interfaced with an HX711 module for weight measurement, an IR sensor, an ADXL345 accelerometer, a VL53L0X distance sensor, and a Neo 6M GPS module for location tracking. The system is designed for wireless data transmission and is supported by a TP4056 module for battery charging.
Open Project in Cirkit Designer
This circuit integrates a Raspberry Pi 5 with an OV2640 camera module, an ILI9488 TFT screen, an infrared proximity sensor, and a load cell with an HX711 sensor module. The system captures images and performs OCR to extract text from documents, displays the text and weight measurements on the TFT screen, and allows data export via WiFi.
Open Project in Cirkit DesignerThe HX711 is a highly integrated ADC with the following key specifications:
| Parameter | Value |
|---|---|
| Supply Voltage | 2.6V to 5.5V |
| Operating Current | ~1.5mA |
| Standby Current | <1µA |
| Resolution | 24-bit |
| Input Channels | 2 (differential inputs) |
| Programmable Gain | 32, 64, or 128 |
| Data Rate | 10 Hz or 80 Hz |
| Temperature Range | -40°C to +85°C |
The HX711 has 16 pins, but the most commonly used package is the SOP-16. Below is the pin configuration:
| Pin | Name | Description |
|---|---|---|
| 1 | VCC | Power supply input (2.6V to 5.5V). |
| 2 | VFB | Feedback voltage for internal regulator (not commonly used). |
| 3 | BASE | Base voltage for internal regulator (not commonly used). |
| 4 | AVDD | Analog power supply (connect to VCC). |
| 5 | AGND | Analog ground. |
| 6 | BGND | Bridge ground (connect to AGND). |
| 7 | B- | Negative input for the bridge sensor (e.g., load cell). |
| 8 | B+ | Positive input for the bridge sensor (e.g., load cell). |
| 9 | VBG | Bridge voltage reference (not commonly used). |
| 10 | VOUT | Output voltage for internal regulator (not commonly used). |
| 11 | DGND | Digital ground. |
| 12 | PD_SCK | Power-down and serial clock input. |
| 13 | DOUT | Serial data output. |
| 14 | DVDD | Digital power supply (connect to VCC). |
| 15 | NC | No connection (leave unconnected). |
| 16 | NC | No connection (leave unconnected). |
PD_SCK pin to a digital output pin on your microcontroller.DOUT pin to a digital input pin on your microcontroller.PD_SCK pin after the DOUT pin goes low.
Below is an example of how to interface the HX711 with an Arduino UNO to read data from a load cell:
#include "HX711.h" // Include the HX711 library
// Define pins for HX711
#define DOUT 3 // Data output pin connected to Arduino pin 3
#define SCK 2 // Serial clock pin connected to Arduino pin 2
HX711 scale; // Create an instance of the HX711 class
void setup() {
Serial.begin(9600); // Initialize serial communication
scale.begin(DOUT, SCK); // Initialize the HX711 with the defined pins
scale.set_scale(); // Set the scale factor (calibration required)
scale.tare(); // Reset the scale to 0
Serial.println("HX711 initialized. Place weight on the scale.");
}
void loop() {
// Read the weight from the load cell
float weight = scale.get_units(10); // Average 10 readings for stability
Serial.print("Weight: ");
Serial.print(weight);
Serial.println(" kg"); // Display weight in kilograms
delay(500); // Wait for 500ms before the next reading
}
Note: The set_scale() function requires calibration. Replace the default value with the calibration factor specific to your load cell.
No Data Output:
DOUT and PD_SCK pins are correctly connected to the microcontroller.Unstable Readings:
Incorrect Weight Measurements:
HX711 Not Responding:
PD_SCK pin is toggling correctly and the clock pulses are within the specified range.DOUT signal.Q: Can the HX711 be used with sensors other than load cells?
A: Yes, the HX711 can be used with other sensors that output small differential signals, such as pressure sensors, provided the input voltage range and gain settings are compatible.
Q: How do I calibrate the HX711?
A: Use a known weight to determine the calibration factor. Adjust the set_scale() function in the code to match the known weight with the measured value.
Q: What is the maximum weight the HX711 can measure?
A: The maximum weight depends on the load cell's capacity and the calibration factor. The HX711 itself does not impose a weight limit.
Q: Can I use the HX711 with a 3.3V microcontroller?
A: Yes, the HX711 operates at 2.6V–5.5V, making it compatible with both 3.3V and 5V systems. Ensure the load cell's excitation voltage is also within this range.