Quickstart

Here you can find a short example how to use the library in your project.

You can also find an example in example folder.

Installation

ESP-IDF

The library contains a idf_compent.yml file. So you can install it with the esp-idf packagemanager to be aviable in your project.

To integerate it to your project create a file named idf_compent.yml and put following lines in it.

dependencies:
    idf: ">=4.4"

    hx711:
        git: https://github.com/avjui/hx711.git

The file was also aviable in the [example folder main dirctory](./example/main/).

After this installation is complete and you can build your project with th hx711 library.

Platformio

To use this library in platformio you can add lib_deps to your configuration file platformio.ini

lib_deps =
    git+https://github.com/avjui/hx711

Warning

Because platformio not regiester the Kconfig by him self you have to add Kconfig with editing CMakeLists.txt, or add the config variables to platfomrio.ini.

First option is to add following lines to CMakeLists.txt in the root directory.

get_filename_component(configName "${CMAKE_BINARY_DIR}" NAME)
list(APPEND kconfigs "${CMAKE_SOURCE_DIR}/.pio/libdeps/${configName}/hx711/Kconfig")

Second option is to add the config to platformio.ini.

[hx711]
; Build flags for hx711 library
build_flags=
    -D CONFIG_HX711_PIN_PDSCK=26 ; clock pin
    -D CONFIG_HX711_PIN_PDOUT=25 ; out pin
    -D CONFIG_HX711_SCALE=491    ; scale factor
    -D CONFIG_HX711_TARETIME=20  ; samples we use for tare
    -D CONFIG_HX711_SAMPLES=10   ; samples we use for avarge value
    -D CONFIG_HX711_WAIT_TIME=2  ; time to wait when toggle pins
    -D CONFIG_HX711_GAIN=1       ; Gain channel A 128=1, 32=3, channel B 64=2

[env:...]
....

build_flags =
    ${hx711.build_flags}

Initialization and setup

At first we must include the header files

#include <hx711.h>

Constructer with default config

After that we can create a Object with the standart config.

This means the configuration made by menuconfig well be used.

Note

There you can find a HX711 Configuration section.

/* Init with default config
*  or config make with 'menuconfig'
*/
HX711 load;

Constructer with custom config

If you want more control over the configuration you can use the overloaded constructer.

Ther you can use the hx711_conf_t struct.

/* Create custom config */
hx711_conf_t conf_hx711 = {
    .pin_pdsck = 26,
    .pin_dout = 27,
    .samples = 10,
    .gain = GAIN_128,
    .scale = SCALE,
};

/* Init with custom config */
HX711 load(&conf_hx711);

Tare the scale

We can tare automaticly to get the right offset

Note

You must be sure that you have nothing on the scale. Otherwise 0 gramm will be set within the weight staying on the scale when the tare function will be execute.

/* Tare the scale */
load.tare();

An other option is to set the offset manual. Maybe from stored value.

/* Set new offset */
float newoffset = 46709.0;
load.setOffset(newoffset);

Usage

Perform update of weight value

Here we have two options to update the cellload value.

One option can be to start the background task.

/* Start background task to periodicly read out value from hx711 modul */
load.startTask();

The other option is to poll it manuely. Be sure that you periodacly execute this function to get a new value.

/* Perform read out value from hx711 modul */
load.update();

Read load value

To read the load you can use the variable cellload. If you have started the background task you can read the value, without doing anything else.

/* Read value and print */
ESP_LOGI("MAIN", "Cell load: [ %.2f gram ] \n", load.cellload);

Note

Default we read the value for 10 times to get an average to have a more accurate result. When the hx711 modul is set to 10Mhz we get all second one result 10MHz/10. After some testing it resuslts that it looks like the modul i testet has about 5Mhz. So we get a result every 2 seconds. You can change this behavier by change the HX711_SAMPLES variable or by using the constructer with custom config.

If you have choose to poll it manuel you must call update before reading.

/* Update variable */
load.update();

/* Read value and print */
ESP_LOGI("MAIN", "Cell load: [ %.2f gram ] \n", load.cellload);