+=item B<Timeout> I<Milliseconds>
+
+The B<Timeout> option sets the overall timeout for HTTP requests to B<URL>, in
+milliseconds. By default, the configured B<Interval> is used to set the
+timeout.
+
+=back
+
+=head2 Plugin C<barometer>
+
+This plugin reads absolute air pressure using digital barometer sensor on a I2C
+bus. Supported sensors are:
+
+=over 5
+
+=item I<MPL115A2> from Freescale,
+see L<http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MPL115A>.
+
+
+=item I<MPL3115> from Freescale
+see L<http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MPL3115A2>.
+
+
+=item I<BMP085> from Bosch Sensortec
+
+=back
+
+The sensor type - one of the above - is detected automatically by the plugin
+and indicated in the plugin_instance (you will see subdirectory
+"barometer-mpl115" or "barometer-mpl3115", or "barometer-bmp085"). The order of
+detection is BMP085 -> MPL3115 -> MPL115A2, the first one found will be used
+(only one sensor can be used by the plugin).
+
+The plugin provides absolute barometric pressure, air pressure reduced to sea
+level (several possible approximations) and as an auxiliary value also internal
+sensor temperature. It uses (expects/provides) typical metric units - pressure
+in [hPa], temperature in [C], altitude in [m].
+
+It was developed and tested under Linux only. The only platform dependency is
+the standard Linux i2c-dev interface (the particular bus driver has to
+support the SM Bus command subset).
+
+The reduction or normalization to mean sea level pressure requires (depending
+on selected method/approximation) also altitude and reference to temperature
+sensor(s). When multiple temperature sensors are configured the minumum of
+their values is always used (expecting that the warmer ones are affected by
+e.g. direct sun light at that moment).
+
+Synopsis:
+
+ <Plugin "barometer">
+ Device "/dev/i2c-0";
+ Oversampling 512
+ PressureOffset 0.0
+ TemperatureOffset 0.0
+ Normalization 2
+ Altitude 238.0
+ TemperatureSensor "myserver/onewire-F10FCA000800/temperature"
+ </Plugin>
+
+=over 4
+
+=item B<Device> I<device>
+
+The only mandatory configuration parameter.
+
+Device name of the I2C bus to which the sensor is connected. Note that
+typically you need to have loaded the i2c-dev module.
+Using i2c-tools you can check/list i2c buses available on your system by:
+
+ i2cdetect -l
+
+Then you can scan for devices on given bus. E.g. to scan the whole bus 0 use:
+
+ i2cdetect -y -a 0
+
+This way you should be able to verify that the pressure sensor (either type) is
+connected and detected on address 0x60.
+
+=item B<Oversampling> I<value>
+
+Optional parameter controlling the oversampling/accuracy. Default value
+is 1 providing fastest and least accurate reading.
+
+For I<MPL115> this is the size of the averaging window. To filter out sensor
+noise a simple averaging using floating window of this configurable size is
+used. The plugin will use average of the last C<value> measurements (value of 1
+means no averaging). Minimal size is 1, maximal 1024.
+
+For I<MPL3115> this is the oversampling value. The actual oversampling is
+performed by the sensor and the higher value the higher accuracy and longer
+conversion time (although nothing to worry about in the collectd context).
+Supported values are: 1, 2, 4, 8, 16, 32, 64 and 128. Any other value is
+adjusted by the plugin to the closest supported one.
+
+For I<BMP085> this is the oversampling value. The actual oversampling is
+performed by the sensor and the higher value the higher accuracy and longer
+conversion time (although nothing to worry about in the collectd context).
+Supported values are: 1, 2, 4, 8. Any other value is adjusted by the plugin to
+the closest supported one.
+
+=item B<PressureOffset> I<offset>
+
+Optional parameter for MPL3115 only.
+
+You can further calibrate the sensor by supplying pressure and/or temperature
+offsets. This is added to the measured/caclulated value (i.e. if the measured
+value is too high then use negative offset).
+In hPa, default is 0.0.
+
+=item B<TemperatureOffset> I<offset>
+
+Optional parameter for MPL3115 only.
+
+You can further calibrate the sensor by supplying pressure and/or temperature
+offsets. This is added to the measured/caclulated value (i.e. if the measured
+value is too high then use negative offset).
+In C, default is 0.0.
+
+=item B<Normalization> I<method>
+
+Optional parameter, default value is 0.
+
+Normalization method - what approximation/model is used to compute the mean sea
+level pressure from the air absolute pressure.
+
+Supported values of the C<method> (integer between from 0 to 2) are:
+
+=over 5
+
+=item B<0> - no conversion, absolute pressure is simply copied over. For this method you
+ do not need to configure C<Altitude> or C<TemperatureSensor>.
+
+=item B<1> - international formula for conversion ,
+See
+L<http://en.wikipedia.org/wiki/Atmospheric_pressure#Altitude_atmospheric_pressure_variation>.
+For this method you have to configure C<Altitude> but do not need
+C<TemperatureSensor> (uses fixed global temperature average instead).
+
+=item B<2> - formula as recommended by the Deutsche Wetterdienst (German
+Meteorological Service).
+See L<http://de.wikipedia.org/wiki/Barometrische_H%C3%B6henformel#Theorie>
+For this method you have to configure both C<Altitude> and
+C<TemperatureSensor>.
+
+=back
+
+
+=item B<Altitude> I<altitude>
+
+The altitude (in meters) of the location where you meassure the pressure.
+
+=item B<TemperatureSensor> I<reference>
+
+Temperature sensor(s) which should be used as a reference when normalizing the
+pressure using C<Normalization> method 2.
+When specified more sensors a minumum is found and used each time. The
+temperature reading directly from this pressure sensor/plugin is typically not
+suitable as the pressure sensor will be probably inside while we want outside
+temperature. The collectd reference name is something like
+<hostname>/<plugin_name>-<plugin_instance>/<type>-<type_instance>
+(<type_instance> is usually omitted when there is just single value type). Or
+you can figure it out from the path of the output data files.
+
+=back
+
+=head2 Plugin C<battery>
+
+The I<battery plugin> reports the remaining capacity, power and voltage of
+laptop batteries.
+
+=over 4
+
+=item B<ValuesPercentage> B<false>|B<true>
+
+When enabled, remaining capacity is reported as a percentage, e.g. "42%
+capacity remaining". Otherwise the capacity is stored as reported by the
+battery, most likely in "Wh". This option does not work with all input methods,
+in particular when only C</proc/pmu> is available on an old Linux system.
+Defaults to B<false>.
+
+=item B<ReportDegraded> B<false>|B<true>
+
+Typical laptop batteries degrade over time, meaning the capacity decreases with
+recharge cycles. The maximum charge of the previous charge cycle is tracked as
+"last full capacity" and used to determine that a battery is "fully charged".
+
+When this option is set to B<false>, the default, the I<battery plugin> will
+only report the remaining capacity. If the B<ValuesPercentage> option is
+enabled, the relative remaining capacity is calculated as the ratio of the
+"remaining capacity" and the "last full capacity". This is what most tools,
+such as the status bar of desktop environments, also do.
+
+When set to B<true>, the battery plugin will report three values: B<charged>
+(remaining capacity), B<discharged> (difference between "last full capacity"
+and "remaining capacity") and B<degraded> (difference between "design capacity"
+and "last full capacity").
+