BUILD A GREENHOUSE MONITOR WITH A RASPBERRY PI
@PCPRO
The Raspberry Pi Sense Hat is a versatile addon, with sensors for temperature, humidity, pressure, orientation and direction, and there are numerous examples of how it can be used online. The European Space Agency has even sent two of them to the International Space Station for conducting experiments in weightless environments (pcpro.link/314astro).
Here at PC Pro, we’re a little more down to earth. To showcase the Sense Hat’s capabilities, we’ll focus on three of those sensors – temperature, humidity and pressure – to build a greenhouse-monitoring system. With winter on the way and gardeners moving vulnerable plants under cover, it makes sense to have a way of keeping an eye on conditions without having to go out and check a thermometer.
We’ll therefore take a reading every 15 minutes and upload the data to a web server so it can be checked from the comfort of a centrally heated home. We’ll also make use of the LED matrix mounted on the Sense Hat’s top surface to give visual feedback should temperatures stray outside of a defined range. That way, if you mount the Pi so it’s visible from the house, you can see at a glance if you need to go out and turn on a heater or open a window, even if you haven’t checked the server.
Naturally, you need a power source wherever you position your Pi plus Sense Hat. If you’re going to use it in an outbuilding, you should also make sure it isn’t going to get wet. You don’t need Wi-Fi if you only want to record your measurements onto the SD card, but you will if you want to upload them to the server, so make sure your network signal carries far enough, or use a booster. If you don’t have a greenhouse, you could use the same technique to monitor the temperature of, say, a nursery, a vivarium housing reptiles or even just your office.
