C Driver and Node Binding for HX711 Load Cell Amp

Prerequisities

• g++-4.8 node-gyp needs to compile with g++ v4.8 due to the version of v8 node uses since some versions. However raspian comes with v4.6 preinstalled. Install it via sudo apt-get install g++-4.8
• WiringPi for the native GPIO handling this libary uses WiringPi. Install it using the instructions on the Website.

API

This library exposes a class with Name HX711 that gives you access to all functions you need to interface.

Constructor(Number clockPin, Number dataPin)

const sensor = new HX711(clockPin, dataPin);

create a new Sensor instance. The pin Numbers should represent the WiringPi Pins the Sensor is connected to. You can have as many HX711 Chips connected as long as they all are connected to a different set of pins.

read()

sensor.read();

Read the raw value as returned from the Sensor. You normally don't call this Method directly, but you may find it useful so I exported it.

getUnits([Number times = 10])

let units = sensor.getUnits();

Read the sensor times times and calculate the average. This returns a scaled value with the offset removed.

tare([Number times = 10])

sensor.tare();

Read the sensor times times and save the average Offset via setOffset().

setOffset([Number offset = 0])

sensor.setOffset(-1000);

set or reset the offset for the sensor

getOffset()

let offset = sensor.getOffset();

get the current offset of the sensor

setScale([Number scale = 1.0])

sensor.setScale(3543.26);

set or reset the scale for the sensor

getScale()

let scale = sensor.getScale();

get the current scale of the sensor

Troubleshooting

It sometimes can happen that the HX711 chip gets in a state where it does not recover itself. This can result in an endless loop while the library waits for the chip to notify a new data set.

If you ever run in a problem where the library does not give you new values, just power cycle the sensor.