Sensor BMP085 for node.js

A node.js module for working with the barometric pressure and temperature sensor BMP085 via i2c.

About the sensor

The BMP085 is a sensor who combines barometric pressure and temperature measurement on a single chip. A breakout with the sensor is available at adafruit or sainsmart. This driver/module based on the datasheet available via adafruit.

Install

$ npm install sensor_bmp085

Raspberry PI

Enable i2c on your Pi if you haven't done already. To avoid having to run the i2c tools as root add the ‘pi’ user to the i2c group:

sudo adduser pi i2c

Usage

The module is easy to use. You have different config-options

Simple Usage

var BMP085 = require('sensor_bmp085');

var sense = new BMP085();
sense.init(function(err, val) {
  if (!err) {
    sense.getTemperature(function(error, val) {
      if (!error) {
        console.log(val + ' °C');
        sense.getPressure(function(error, val) {
          if (!error) {
            console.log(val + ' °C');
          }
        });
      }
    });
  }    
});

Don't forget to call init()

ìnit() reads the calibration data from sensors EEPROM and sets the given options.

Options

The default options are:

{
  'debug': false,
  'address': 0x77,
  'device': '/dev/i2c-1',
  'sensorMode': 'ultraHighRes',
  'maxTempAge': 1,
}

Configure the sensor by supplying an options object to the constructor like:

var sense = new BMP085({
  'sensorMode': 'ultraLowPower',
  'maxTempAge': 5,
});

What does 'maxTempAge' mean

For the calculation of the air pressure, a temporary result of the temperature calculation is required. maxTempAge says how old (in seconds) may be the temperature measurement before a new temperature measurement is required. If the temperature measurement is too old a new one will be started automatically.

Getter & Setter for sensor settings

Getter supports only callbacks. Setter supports callbacks and event-emitters - sensorSettingChanged and sensorSettingFailed. Getter and setter are:

getSensorMode(cB) / setSensorMode(newMode, [cB]) / modes: 'ultraLowPower', 'standard', 'highRes', 'ultraHighRes'
getMaxTempAge(cB) / setMaxTempAge(newMode, [cB]) / modes: 1 ... 60 (in seconds)

Light-Measurements

Measurement-functions using a callback and some of them an event-emitter. All events including a timestamp and additional data like the address to determine the sensor, who emitted the event.

• getTemperature([cB]) - the calculated temperature value in °C - emits event newSensorValue on success or sensorValueError on error
• getPressure([cB]) - the calculated pressure value in hPa - emits event newSensorValue on success or sensorValueError on error
• getAllValues([cB]) - all values (raw and calculated) - emits event newSensorValues on success or sensorValuesError on error

Tests

Because it's not really a good idea to run test in an unknown environment all tests under test using a faked devices and not really your i2c bus. The faked device using a faked i2c-bus which is realised with the proxyquire module.

To run the complete test suite nodeunit is required. The best way is using grunt and the shipped gruntfile which comes with this module.

Examples

All examples are using a real device on address 0x77 on your i2c bus. Be carefully if you have more as one device on your i2c or/and if you don't use the default address for the sensor.

Licence

The licence is GPL v3 and the module is available at Bitbucket and GitHub.