Meteo-Pi is a flexible, low-cost data-centre device for Davis weather stations. It’s a great new way of linking a Davis console to a powerful but green and inexpensive Raspberry Pi computer.
Meteo-Pi is a two-part cabled adapter linking a standard Davis weather station console (VP2, Envoy or Vue) to a Raspberry Pi computer. The two parts are: a console interface that fits into the console much like a traditional logger and a Raspberry Pi input adapter in the form of a microHAT (µHAT), which means that it plugs directly on to the interface pins of the Pi. The two parts are joined by a Davis-compatible cable with RJ11 connectors. Meteo-Pi appears to software running on the Pi computer as a simple serial device (ie connecting via a COM port) and so virtually any Pi-compatible software should be able to receive data from the console and in the same formats as any other Davis logger.
Meteo-Pi’s main advantage is that it allows any weather station programs able to run on the Raspberry Pi to receive serial weather data direct from the console. This provides two key benefits:
- It allows a choice of weather programs to run on the Pi . If you try one program but decide that it doesn’t meet your requirements then it’s simple to switch to an alternative Pi-compatible program. Or Meteo-Pi may be ideal for developing your own Pi-compatible software. Contrast this with a combined logger/SBC like the WiFi Logger or Meteobridge Nano, which are both great devices but limited to the built-in software;
- Much greater memory and computing power is available with a Pi (especially if the new high-performance Raspberyy Pi 4 is used) than an integrated logger/SBC ;
The simplicity of the Meteo-Pi design allows it to be sold at relatively low cost. Of course you still need to buy a Pi and a few associated accessories (power supply, SD card etc) but it should still be possible to build a complete and reasonably powerful data-handling solution, including the Meteo-Pi unit itself, for around $/€/£120 (and remember that Meteo-Pi does not need a separate logger – other than the Pi, it is fully self-contained).
Meteo-Pi also offers some other important features:
- LED indicators on the µHAT board provide a constant visual indication of communication between the console and Pi;
- All Raspberry Pi computers are green in the sense that they have very low power consumption. A Pi can be left running 24/7 and feeding your weather data up to the Internet while consuming no more electrical power than a small mains LED light;
- RTC: Meteo-Pi has a battery-backed real-time clock so that accurate time can be maintained on the Pi even after a mains outage;
- There is full electrical isolation between console and Pi so issues like ground loops leading to spurious readings cannot occur. This makes Meteo-Pi especially suitable for cabled VP2 installations. (Of course, Meteo-Pi works perfectly well with wireless stations too.)
- Zero configuration required during set-up;
- Option to power a Vue/VP2 console from the Meteo-Pi so only a single mains adapter is required;
- No USB connection is involved, so potential issues like USB dropout, USB drivers, a separate USB hub etc are not relevant;
Remember also that most recent Pi versions are available with WiFi onboard and so it’s perfectly possible to locate a miniature Pi computer close to your Davis console and have it talking to other computers on your network and to the Internet over WiFi.
Cables: Meteo-Pi is supplied with two 20cm (8″) cables. One is a 4-conductor and the other a 6-conductor cable. If the 4-conductor one is used then this connects only the data wires between console and Pi. The 6-conductor one allows back-powering of the console from the Pi. The user chooses which cable to use. Both cables are terminated with standard RJ11-type plugs. If the 4-conductor MP cable is used then standard Davis extension cables can be used to provide a longer cable connection (for which we’d suggest a 12m (40ft) extension as a maximum).
A great Raspberry Pi project
If you’ve heard of Raspberry Pi computers but wondered what all the fuss was about then setting up a Meteo-Pi unit with a spare Vue/VP2 wireless console makes a great project, maybe for the winter evenings? Not only will the project be an end in itself and create a dedicated weather computer able to run 24/7 at minimal cost, but the project provides an opportunity to learn a lot more about Raspberry Pi computers in general and maybe suggest other interesting applications for a Pi too.
See our blogs section for more information
We will be adding some posts in our Blogs section that add more detail about setting up and running a Meteo-Pi unit, including choosing a Pi model and what’s involved in running a Pi. The first part can be found here.