Hygrometer

The Hygrometer class constructs objects that represent a single Hygrometer sensor attached to the physical board. Hygrometers are used to measure absolute and relative humidity.

Supported Hygrometers:

• BME280
  • Adafruit
  • Sparkfun
• HTU21D
  • Adafruit
  • Sparkfun
• HIH6130
  • Sparkfun
• TH02
  • Grove
• SI7020
  • Tessel Climate
• SI7021
  • Sparkfun
• SHT31D
  • Adafruit
• DHT11 (Via I2C Backpack)
  • Google
• DHT21 (Via I2C Backpack)
  • Google
• DHT22 (Via I2C Backpack)
  • Google

This list will continue to be updated as more devices are confirmed.

Parameters

• General Options

  Property	Type	Value/Description	Default	Required
  controller	string	BME280, HTU21D, HIH6130, TH02, SI7020, SI7021, SHT31D. The Name of the controller to use.		no
  freq	Number	Milliseconds. The rate in milliseconds to emit the data event	25ms	no

Shape

Property Name	Description	Read Only
id	A user definable id value. Defaults to a generated uid	No
relativeHumidity	The relative humidity in percent.	Yes
RH	A convenience alias for relativeHumidity.	Yes

Component Initialization

HTU21D

new five.Hygrometer({
  controller: "HTU21D"
});

HIH6130

new five.Hygrometer({
  controller: "HIH6130"
});

SI7020

new five.Hygrometer({
  controller: "SI7020"
});

SI7021

new five.Hygrometer({
  controller: "SI7021"
});

TH02

new five.Hygrometer({
  controller: "TH02"
});

DHT11_I2C_NANO_BACKPACK

new five.Hygrometer({
  controller: "DHT11_I2C_NANO_BACKPACK"
});

DHT21_I2C_NANO_BACKPACK

new five.Hygrometer({
  controller: "DHT21_I2C_NANO_BACKPACK"
});

DHT22_I2C_NANO_BACKPACK

new five.Hygrometer({
  controller: "DHT22_I2C_NANO_BACKPACK"
});

Usage

var five = require("johnny-five");
var board = new five.Board();

board.on("ready", function() {

  var hygrometer = new five.Hygrometer({
    controller: "HTU21D"
  });

  hygrometer.on("change", function() {
    console.log(this.relativeHumidity + " %");
  });
});

API

There are no special API functions for this class.

Events

• change The "change" event is emitted whenever the value of the relative humidity changes.

• data The "data" event is fired as frequently as the user defined freq will allow in milliseconds. ("data" replaced the "read" event)