Tutorial: Part 11 -Building a Solar Powered Raspberry Pi Weather Station – GroveWeatherPi

The Raspberry Pi is a fabulous device to on which to build your projects.    The GroveWeatherPi project is designed to show the capabilities of this computer while remaining accessible to a diverse Maker community.

GroveWeatherPi is a Solar Powered Raspberry Pi WiFi connected weather station designed for Makers by SwitchDoc Labs ( www.switchdoc.com). This is a great system to build and tinker with. All of it is modifiable and all source code is included.

This tutorial for building your own Solar Powered Weather Station based on the Raspberry Pi consists of 14 parts.

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The Raspberry Pi Python Software

A big part of the GroveWeatherPi project is the software. All of the python software for this project is up on github at the switchdoclabs section ( github.com/switchdoclabs/SDL_Pi_GroveWeatherPi ). We also included all of the various libraries for the I2C devices we are using.

Non-Normal Requirements for your Pi

You will need to add the following software and libraries to your Raspberry Pi

MySQL

There are lots of tutorials on the net for installing MySQL. Here is the one we used (https://howtoraspberrypi.com/mariadb-raspbian-raspberry-pi/).

 

sudo apt-get install python-mysqldb

MatPlotLib

This is the graphing subsystem with a great interface to Python. It is a bit more complex to install, so we wrote a tutorial on how to install it on SwitchDoc.com ( https://www.switchdoc.com/2014/01/matplotlib-raspberry-pi-mysql-and-project-curacao/ ). Note that the installation takes a long time, about 8 hours on a Raspberry Pi B+ (mostly unattended).

 

The GroveWeatherPi Python Software 

The GroveWeatherPi software is pretty simple. The application was much less complex than the Project Curacao software( https://www.switchdoc.com/project-curacao-software-system-part-6/ ) so we decided not use the apscheduler package and decided just to use a simple loop with a “every 15 seconds” type of control.

Here is the main loop:

secondCount = 1
while True:

        # process Interrupts from Lightning

        if (as3935Interrupt == True):

                try:
                        process_as3935_interrupt()


                except:
                        print "exception - as3935 I2C did not work"


        if (config.TCA9545_I2CMux_Present):
                tca9545.write_control_register(TCA9545_CONFIG_BUS0)
        # process commands from RasPiConnect
        print "---------------------------------------- "

        processCommand()

        if ((secondCount % 10) == 0):
                # print every 10 seconds
                sampleAndDisplay()
                patTheDog()      # reset the WatchDog Timer
                blinkSunAirLED2X(2)




        # every 5 minutes, push data to mysql and check for shutdown


        if ((secondCount % (5*60)) == 0):
                # print every 300 seconds
                sampleWeather()
                sampleSunAirPlus()
                writeWeatherRecord()
                writePowerRecord()

                if (batteryVoltage < 3.5): print "--->>>>Time to Shutdown<<<<---"
                        shutdownPi("low voltage shutdown")


        # every 15 minutes, build new graphs

        if ((secondCount % (15*60)) == 0):
                # print every 900 seconds
                sampleWeather()
                sampleSunAirPlus()
                doAllGraphs.doAllGraphs()

        # every 30 minutes, check wifi connections

        if ((secondCount % (30*60)) == 0):
                # print every 900 seconds
                WLAN_check()

        #WLAN_check()


        # every 48 hours, reboot
        if ((secondCount % (60*60*48)) == 0):
                # reboot every 48() hours seconds
                rebootPi("48 hour reboot")


        secondCount = secondCount + 1
        # reset secondCount to prevent overflow forever

        if (secondCount == 1000001):
                secondCount = 1

        time.sleep(1.0)

Note that we reboot the Pi every two days. Why do we do that? We have noticed that after heavy usage of MatPlotLib and/or MySQL, that sometimes after a long time, you run out of resources, giving all sorts of odd behavior. Since the RaspberryPi A+ has a small amount of RAM, rebooting is the easiest way of fixing it.

Check out all the code up on github.com (  github.com/switchdoclabs/SDL_Pi_GroveWeatherPi ).