Rando HX711 Arduino Library

Copyright (c) 2015 Scott Russell (scott@queuetue.com), Copyright (c) 2024 David Johnston (dwjgame11@gmail.com), released under the MIT license. See the LICENSE file for licensing details.

This library is a fork of the Queuetue HX711 Library.

A simple Arduino driver for the HX711 ADC.

The HX711 is a low-cost strain gauge amplifier produced by Avia Semiconductor. Breakout boards are available for it by many producers, including the Sparkfun 13230.

The HX711 communicates with a non-i2c compliant two wire protocol and provides an all-in-one solution to load cell amplification with relatively low noise.

This library provides the code required to use an Arduino, the HX711 module and a strain gauge load cell to build a scale, force gauge or many other pressure or force sensitive projects.

The library has a single class, Q2HX711 with five functions.

Class

The Q2HX711 class requires two parameters on construction, the pin to use for data (output) and the pin to use to signal readiness (clock). An optional scale factor can also be given; this is the highest/lowest value that can be reached, and is useful for calculating absolute values like mV. For example, if you have an HX711 board that can measure voltages between -20 and 20 mV, set this to 20.

Functions

Function	Description
readRaw	Returns a long integer that is the current value of the HX711, unconverted and unaltered.
read	Returns a long integer that is the current value of the HX711. This is scaled to always be positive.
readSigned	Returns a long integer that is the current value of the HX711, sign extended to 32 bits.
readUnits	Returns a double of the current value from the HX711, scaled to fit in the range [-x,x), where x is the unit scale passed on initialization.
readyToSend	Returns a boolean indicating if the HX711 is prepared to send data.

Example

Here is a simple example of using the HX711 on pins A2 and A3 to read a strain gauge and print it's current value:

#include <Q2HX711.h>
Q2HX711 hx711(A2, A3);
void setup() {
  Serial.begin(9600);
}

void loop() {
  Serial.println(hx711.read());
  delay(500);
}

Here is a similar example that scales the HX711 output from +-8 million to +-20.0:

#include <Q2HX711.h>
Q2HX711 hx711(A2, A3, 20.0);
void setup() {
  Serial.begin(9600);
}

void loop() {
  Serial.println(hx711.readUnits());
  delay(500);
}

This latter example is useful for converting from the measured integer value to the raw mV differential voltage measured by the sensor.