- Order number: CH-9256-P
- Manufacturer product ID: 9256-P
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 normally open that closes for a short period of time when the arms of the anemometer complete a turn, so the output is a digital signal whose frequency will be proportional to the wind speed in kilometers per hour (km/h).
Sensor specifications (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, which 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, whose 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:
| Direction (Degrees) | Resistance (kΩ) | Voltage (V) | Identifier |
| 0 | 33 | 2.53 | SENS_AGR_VANE_N |
| 22.5 | 6.57 | 1.31 | SENS_AGR_VANE_NNE |
| 45 | 8.2 | 1.49 | SENS_AGR_VANE_NE |
| 67.5 | 0.891 | 0.27 | SENS_AGR_VANE_ENE |
| 90 | 1 | 0.3 | SENS_AGR_VANE_E |
| 112.5 | 0.688 | 0.21 | SENS_AGR_VANE_ESE |
| 135 | 2.2 | 0.59 | SENS_AGR_VANE_SE |
| 157.5 | 1.41 | 0.41 | SENS_AGR_VANE_SSE |
| 180 | 3.9 | 0.92 | SENS_AGR_VANE_S |
| 202.5 | 3.14 | 0.79 | SENS_AGR_VANE_SSW |
| 225 | 16 | 2.03 | SENS_AGR_VANE_SW |
| 247.5 | 14.12 | 1.93 | SENS_AGR_VANE_WSW |
| 270 | 120 | 3.05 | SENS_AGR_VANE_W |
| 292.5 | 42.12 | 2.67 | SENS_AGR_VANE_WNW |
| 315 | 64.9 | 2.86 | SENS_AGR_VANE_NW |
| 337.5 | 21.88 | 2.26 | SENS_AGR_VANE_NNW |
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.
Sensor specifications (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.
