Tutorial to Interface HX711 Balance Module With Load Cell

Description

This module uses 24 high-precision A / D converter. This chip is designed for high-precision electronic scale and design, has two analog input channels, programmable gain of 128 integrated amplifier. The input circuit can be configured to provide a bridge voltage electrical bridge (such as pressure, load) sensor model is an ideal high-precision, low-cost sampling front-end module.

Specification

Two selectable differential input channels
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
Data Accuracy: 24 bit (24 bit analog-to-digital converter chip)
Refresh Frequency: 10/80 Hz
Operation supply voltage range: 4.8 ~ 5.5V
Operation supply Current: 1.6mA
Operation temperature range: -20 ~ +85℃
Demension: Approx. 36mm x 21mm x 4mm / 1.42" x 0.83" x 0.16"

Step 1: Material Preparation

In this tutorial, you will need :

1. Arduino Uno Board and USB

2. HX711 Balance Sensor

3. Load Cell (can be any weight of load cell ie 20KG, 60KG or 100KG)

4. Male Female Jumpers

5. Crocodile Clip Wires

5. Arduino IDE

Step 2: HX711 Pin Description

Step 3: Load Cell Wire Connection

The four wires coming out from the wheatstone bridge on the load cell are usually :

Excitation+ (E+) or VCC is red
Excitation- (E-) or ground is black
Output+ (O+), Signal+ (S+)+ or Amplifier+ (A+) is white
Output- (O-), Signal- (S-)+ or Amplifier- (A-) is green

Step 4: Hardware Installation

HX711 to Arduino Uno :

VCC to 5V
GND TO GND
SCK to D5
DT TO D6

Load Cell to HX711

E+ : RED
E- : BLACK
A- : WHITE
A+ : GREEN

Then, connect your Arduino Uno Board to your Computer via USB.

Step 5: HX711 Library

Communicating with the Balance Module requires a driver for the HX711 sensor. The simplest way to install the driver is to download the HX711 library. Download the ZIP file below > Open Zip File > Extract to your Arduino Uno Library folder. Refer the image above for your references.

HX711.zip
Download

Step 6: Sample Source Code

Download the sample source code below, open and upload this sample source code into your Arduino IDE.

NOTE : You can change your calibration factor before uploading the code OR you can adjust it later in the serial monitor box since the code allow you to add and substract the value of calibration factor.

HX711.rar
Download

Step 7: Serial Monitor

When you has succesfully uploaded the sample source code into your Arduino Uno Board. Open Serial Monitor and it will show u as shown in the picture above.

Step 8: Result

when the serial monitor give u a value for reading, it means that u has succesfully interface your load cell. Now, you can set your own calibration factor by adjusting the value using the '+' or 'a' to increase the value OR '-' or 'z' to decrease the value. You have to calibrate only once for each load cell.

NOTE : This tutorial only show you on how to interface HX711 with load cell. We did not use the correct calibration factor. You have to set your own calibration factor for your load cell. Check on this video and tutorial to learn on how to set the calibration factor for load cells. Remember that each load cell with different weight ie. load cell 20KG, 60Kg and 100KG have different value of calibration factor. Thus, you will have to set calibration factor for each load cell with different weight.