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Example using the SparkFun HX711 breakout board with a scale
By: Nathan Seidle
SparkFun Electronics
Date: November 19th, 2014
License: This code is public domain but you buy me a beer if you use this and we meet someday (Beerware license).
Most scales require that there be no weight on the scale during power on. This sketch shows how to pre-load tare values
so that you don't have to clear the scale between power cycles. This is good if you have something on the scale
all the time and need to reset the Arduino and not need to tare the scale.
This example code uses bogde's excellent library:
bogde's library is released under a GNU GENERAL PUBLIC LICENSE
The HX711 does one thing well: read load cells. The breakout board is compatible with any wheat-stone bridge
based load cell which should allow a user to measure everything from a few grams to tens of tons.
Arduino pin 2 -> HX711 CLK
3 -> DOUT
5V -> VCC
The HX711 board can be powered from 2.7V to 5V so the Arduino 5V power should be fine.
#include "HX711.h"
#define calibration_factor -7050.0 //This value is obtained using the SparkFun_HX711_Calibration sketch
#define zero_factor 8421804 //This large value is obtained using the SparkFun_HX711_Calibration sketch
#define DOUT 3
#define CLK 2
HX711 scale(DOUT, CLK);
void setup() {
Serial.println("Demo of zeroing out a scale from a known value");
scale.set_scale(calibration_factor); //This value is obtained by using the SparkFun_HX711_Calibration sketch
scale.set_offset(zero_factor); //Zero out the scale using a previously known zero_factor
void loop() {
Serial.print("Reading: ");
Serial.print(scale.get_units(), 1); //scale.get_units() returns a float
Serial.print(" lbs"); //You can change to kg but you'll need to change the calibration_factor