node package manager



Node.js versions NPM version

Welcome to si7021-sensor, a Node.js I2C module for the Silicon Labs Si7021 Temperature and Humidity Sensor. Adafruit sells a Si7021 breakout board and here is the datasheet.

This module uses i2c-bus which should provide access with Node.js on Linux boards like the Raspberry Pi Zero, 1, 2, or 3, BeagleBone, BeagleBone Black, or Intel Edison.

Since si7021-sensor needs to talk directly to the I2C bus and requires access to /dev/i2c, you will typically need run Node with elevated privileges or add your user account to the i2c group: $ sudo adduser $USER i2c

Example Code

const Si7021 = require('si7021-sensor');
// Si7021 constructor options object is optional, i2cBusNo defaults to 1
const si7021 = new Si7021({ i2cBusNo : 1 });
const readSensorData = () => {
    .then((data) => {
      console.log(`data = ${JSON.stringify(data, null, 2)}`);
      setTimeout(readSensorData, 2000);
    .catch((err) => {
      console.log(`Si7021 read error: ${err}`);
      setTimeout(readSensorData, 2000);
  .then((result) => readSensorData())
  .catch((err) => console.error(`Si7021 reset failed: ${err} `));

Example Output

> sudo node example.js          
data = {
  "humidity": 43.030303955078125,
  "temperature_C": 26.220090332031255

Example Wiring

For an example of I2C setup on a Raspberry Pi, take a look at my pi-weather-station project.