Weather Station

Sensor Specifications

Anemometer

Sensitivity: 2.4 km/h / turn
Wind Speed Range: 0 ~ 240 km/h
Height: 7.1 cm
Arm length: 8.9 cm
Connector: RJ11

The anemometer chosen for Waspmote consists of a Reed switch which is normally open and that closes for a short period of time when the arms of the anemometer complete a turn, so the output is a digital signal of which the frequency will be proportional to the wind speed in kilometers per hour (km/h).

Vane

Height: 8.9 cm
Length: 17.8 cm
Maximum accuracy: 22.5º
Resistance range: 688 Ω ~ 120 kΩ

The wind vane consists of a basement that turns freely on a platform endowed with a net of eight resistances connected to eight switches that are normally open and are closed (one or two) when a magnet in the basement acts on them. This permits us to distinguish up to 16 different positions (the equivalent to a resolution of 22.5º). The equivalent resistance of the wind vane, along with a 10 kΩ resistance, form a voltage divider, powered at 3.3 V, of which the output can be measured in an analog input of the microcontroller. The function of the library readValue also stores in variable vane direction an 8 bits value which corresponds with an identifier of the pointing direction. Below, a table with the different values that the equivalent resistance of the wind vane may take is shown, along with the direction corresponding to each value:



Besides, it is recommended to use the function getVaneFiltered in order to perform a mean filtered measurement during a specified period of time. Thus, mechanical fluctuations will be avoided and a more accurate measurement will be done.

Pluviometer


Height: 9.05 cm
Length: 23 cm
Bucket capacity: 0.28 mm of rain

The pluviometer consists of a small bucket that, once completely filled (0.28 mm of water approximately), closes a switch, emptying automatically afterwards.The result is a digital signal whose frequency is proportional to the intensity of rainfall in millimeters of rain per minute (mm/min).
The sensor is connected directly to a Waspmote digital input through a pull-up resistance and to the interruption pin TXD1, allowing the triggering of an interruption of the microprocessor when the start of the rain is detected.Tip: the user can apply a little of paraffin on the pluviometer’s upper surface in order to help the rain drops to flow down to the inside of the sensor.
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