1-wire weatherstation

Your computer then receives signals from the devices, allowing you to track rainfall, temperature, humidity, soil moisture levels, lightning, and a host of other information.

A 1-Wire network consists of a master controller which is connected to one or more slave devices.

The master controller is typically a computer or microcontroller with an external 1-Wire interface such as our Serial Adaptor or USB Adaptor.

All of the actual monitoring devices (temperature, humidity, solar radiation, barometer, etc.) are slave devices.

The master communicates with one or more slave device(s) using the serial 1-Wire protocol developed by Dallas Semiconductor, sending and receiving signals over a single data line plus ground reference.

The 1-Wire protocol synchronizes the slave devices to the master.

The master initiates and controls all activities on the 1-Wire network.

1.5 Sensors

1.5.1 Indoor Temperature.

The indoor temperature sensor is constructed from a 1-wire kit from Hobby-Boards; it uses the DS18S20 1-Wire Parasite-Power Digital Thermometer chip from Dallas Semiconductor.

This temperature-sensor shares circuit board with the indoor humidity-sensor.

Temperature range: -55^oC to 125^oC

Accuracy: ± 0.5^oC

Resolution: 0.5^oC

Device Address: 920008018A290C10

1.5.2 Indoor Humidity.

The indoor humidity sensor is constructed from a 1-wire kit from Hobby-Boards; it uses the DS2438Z 1-wire chip and a HIH-4000-001 humidity-sensor from Honeywell.

This humidity-sensor shares circuit board with the indoor temperature-sensor.

The range is 0-100% Relative Humidity.

The accuracy is ± 2%.

The resolution is ± 0.5%.

Device Address: 98000000C1B8C826

1.5.3 Barometer.

The barometer is situated indoor together with temperature- and humidity sensors.

The reason for this being that the atmospheric pressure indoor an outdoor is virtually the same.

And leaving the pressure sensor outside exposed to possible high humidity will considerably shorten its life.

1-wire barometer kit from Hobby-Boards consists of a DS2438Z 1-wire smart battery monitor chip and a MPXA4115A pressure-sensor from Motorola.

Pressure range: 948-1083 mb.

Resolution: 0.34 mb.

This barometer is to be calibrated for the altitude it’s used.

As this board is to be supplied with 14V, an external power-source is required.

Device Address:

1.5.4 Outdoor Temperature.

The outdoor temperature sensor is constructed from a 1-wire kit from Hobby-Boards; it uses the DS18S20 1-Wire Parasite-Power Digital Thermometer chip from Dallas Semiconductor.

This temperature-sensor shares circuit board with the outdoor humidity-sensor.

The board itself is mounted inside an air and watertight IPX class junction box.

The temperature-sensor is mounted inside a ventilated stainless steel tube.

Everything is then placed inside a Stevenson Screen.

Temperature range: -55^oC to 125^oC

Accuracy: ± 0.5^oC

Resolution: 0.5^oC

Device Address: 240008018A06A010

1.5.5 Outdoor Humidity.

The outdoor humidity sensor is a 1-wire kit from Hobby-Boards; it uses the 1-wire smart battery monitor chip and a HIH-4000-001 sensor from Honeywell

This humidity-sensor shares circuit board with the outdoor temperature-sensor.

The board itself is mounted inside an air and watertight IPX class junction box.

The temperature-sensor is mounted inside a ventilated stainless steel tube.

Everything is then placed inside a Stevenson Screen.

The range is 0-100% Relative Humidity

The accuracy is ± 2%.

The resolution is ± 0.5%.

Device Address: 72000000C1ABEA26

1.5.6 Rain Gauge.

The rain gauge is self designed and self-made.

The collector area is 314 cm² (200 mm diameter).

A self-emptying tipping bucket which holds 3.14 cm² activates a reed-switch (NO) every time it tips.

This in turn gives a 0.1 mm pr. tip.

The reed-switch is connected to a 1-wire dual counter.

A dual counter kit from Hobby-Boards is based on a DS2423 4kbit 1-Wire RAM with Counter.

This rain gauge also has heated base and collector funnel, for melting and counting snow, sleet and hail.

Heating is provided with industry grade, self regulating (10^oC ) electrical heat-tracing.

Device Address: FE0000000DF31E1D

1.5.7 Solar Radiation Detector.

Solar radiation detector kit from Hobby-Boards is used for measuring solar radiation.

The Solar Radiation detector measures sunlight. It detects light in the visible to infrared portion of the spectrum, with peak detection at 860nm and an acceptance angle of 140 degrees.

The sensor used for this application is: CLD140 Silicon Planar photodiode from Clairex

Board and sensor are mounted inside a white polycarbonate sphere with a 170 mm outside diameter.

Device Address: 04000000C1960B26

1.5.8 Anemometer.

Anemometer is an instrument for measuring wind speed and direction.

The anemometer used for my weather station is an ultrasonic type.

The anemometer measures the time taken for an ultrasonic pulse to travel from one transducer to the opposite transducer and then compares it with the time taken for another pulse to travel in the opposite direction.

Likewise, differences are measured between other pairs of transducers allowing calculations of both wind speed and direction.

The model used in my setup is a WindObserver II from Gill Instruments.

Range: 0 - 65 m/s (0 - 145mph)

Starting Threshold: 0.01 m/s

Accuracy: 2%

Offset: ± 0.01 m/s

Dead Band Direction: None

Accuracy: ± 2^o

Resolution: 1^o

1.5.9 Stevenson Screen.

A Stevenson Screen is used for protection of temperature- and humidity sensors from precipitation and direct heat radiation and at the same time provide air to circulate around the sensors.

The Stevenson Screen is a box shape, constructed of wood, in a double-louvered design.

The inside dimensions are: WxHxD 400x300x300mm.

The screen is coated with 3 coats of white paint (Jotun Oljedekkbeis)

The height above ground is aprox. 1.5 m when mounted on top of a stainless steel stand (in accordance with World Meteorological Organization agreed standard for the height of the thermometers is between 1.25 m (4 ft 1 in) and 2 m (6 ft 7 in) above the ground.)

2 Documentation.

2.1 General documentation

Wiring diagram