I am using an Arduino Uno and HX711 amplifier to collect data from a load cell. I previously had the load cell calibrated and functioning, but now the load cell will not read any values; only 0's are outputted, even when I apply a small load to the sensor. I have re-soldered and replaced the connecting wires. Are there any suggesting for getting a readout from my sensor?

I have been testing with 2 different load cells: Sparkfun's TAL220 Straight Bar 10kg load cell and an LFS 210-300 from Cooper Instruments (the latter is the one I want to use long term). My load cell is connected like the HX711 Breakout Guide (with an Arduino Uno instead of a RedBoard and a USB connection):

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I have been using the HX711 Breakout Guide Calibration sketch to test my load cell:

#include <HX711.h>

#define DOUT 3
#define CLK 2

HX711 scale(DOUT, CLK);

float calibration_factor = 282650; //-7050 worked for my 440lb max scale setup

void setup() {
  Serial.println("HX711 calibration sketch");
  Serial.println("Remove all weight from scale");
  Serial.println("After readings begin, place known weight on scale");
  Serial.println("Press + or a to increase calibration factor");
  Serial.println("Press - or z to decrease calibration factor");

  scale.tare(); //Reset the scale to 0

  long zero_factor = scale.read_average(); //Get a baseline reading
  Serial.print("Zero factor: "); //This can be used to remove the need to tare the scale. Useful in permanent scale projects.

void loop() {

  scale.set_scale(calibration_factor); //Adjust to this calibration factor

  Serial.print("Reading: ");
  Serial.print(scale.get_units(), 1);
  Serial.print(" kgs"); //Change this to kg and re-adjust the calibration factor if you follow SI units like a sane person
  Serial.print(" calibration_factor: ");

    char temp = Serial.read();
    if(temp == '+' || temp == 'a')
      calibration_factor += 10;
    else if(temp == '-' || temp == 'z')
      calibration_factor -= 10;

I am still new to Arduino and data acquisition in general, so any suggestions would be appreciated!

1 Answer 1


This line is where you are reading the data and printing it:

Serial.print(scale.get_units(), 1);

The 1 on the end of the line defines how many digits you are displaying from your reading. I have a similar setup to yours and I have it set to 5 which shows up to +/-0.00001kg. (Obviously, the accuracy will be different depending on which load cell you have)

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