htu21d
v0.2.0
Published
node interface for the HTU21D temperature and humidity sensor
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htu21d
node interface for the HTU21D temperature and humidity sensor for Raspberry Pi
Install
$ npm install htu21d
Usage
var htu21d = require('htu21d');
var device = "/dev/i2c-1"
var address = 0x40;
var sensor = new htu21d.Htu21d(device, address);
var temp = sensor.temperature();
var humidity = sensor.humidity();
# turn on the internal heater
sensor.setHeater(true)
var check_temp = sensor.temperature();
var check_humidity = sensor.humidity();
# disable the internal heater
sensor.setHeater(false);
# set the measurement resolution, explained in the README
sensor.setMode(3);
var temp_lowres = sensor.temperature();
the htu21d object contains fields for sensor resolution, lowbattery status, and on-chip heater, as per the chip's capabilities, as well as devnode and chip address
> sensor
{ heater: false,
lowbattery: false,
resolution: { mode: 0, temperature: 14, humidity: 12 },
devnode: '/dev/i2c-1',
address: 64 }
The HTU21D has 4 modes for resolution, for which there is unfortunately no good way to express.
To change the resolution, consult the following table:
|mode | Temp | Humidity |
|-----|-------|----------|
| 0 |14 bit |12 bit |
| 1 |12 bit |8 bit |
| 2 |13 bit |10 bit |
| 3 |11 bit |11 bit |
Raspberry Pi Setup
$ sudo vi /etc/modules
Add these two lines
i2c-bcm2708
i2c-dev
$ sudo vi /etc/modprobe.d/raspi-blacklist.conf
Comment out blacklist i2c-bcm2708
#blacklist i2c-bcm2708
Load kernel module
$ sudo modprobe i2c-bcm2708
Questions?
http://www.twitter.com/johnnysunshine