Not all of us understand weather mechanisms, how storms develop or what a low pressure front means so having a weather station that measures these parameters and display them as numbers might not be that helpful. However a team from Cornell University designed and built a station that displays a graphic representation of the current weather condition. If its stormy outside you will see a cloud with some raindrops and a lightning, all this on a 8×8 RGB LED matrix.
There are two main modules making this station. The outdoor module who makes all the measurements and then sends the data wirelessly to the indoor module which will display the icon corresponding to the data received. The data transmission is done onÂ 433MhzÂ by two Linx Technologies modules models RXD-433-KH2 and TXD-433-KH2. These modules also take care of data encoding and decoding using an address code so that only your specified modules will receive the transmission.
The outside station has five sensors to measure weather parameters. A solar cell, which also provides power, measures the light intensity and so it can tell if it’s day or night, cloudy or sunny. A LM34 is used as the temperature sensor and outputs a 10mV with every degree F. Rain sensor is from a Hot Wheels Radar Gun, using a Doppler Radar operating at 10.525GHz is sensitive enough to measure velocity of rain drops. A Diy anemometer was the choice as wind speed measurement tool and a capacitor who changes capacitance based on humidity is used for the last measurement.
ATmega644 is the microcontroller gathering data from all the sensors. This is then transmitted as a 10 bits code, each sensor data havingÂ 2 bits in that message. Inside the indoor module we find another ATmega644 who controls the LED matrix. Using PWM to drive the LEDs a very high number of colors is achieved instead of the usual 8 colors.
This project offers a large amount of information and insight into weather monitoring systems. It will require some skills to built it, specially the anemometer, it not as easy as it looks but it’s worth it.