Connecting to the Internet

The easiest way build a base station for relaying data heard via Xbee is to use an Uno Ethernet board (it’s like an Uno but has built-in ethernet hardware, so no separate shield is needed). Then connect the Xbee to the Uno Ethernet and write a script to capture all the incoming Xbee data and send it to the appropriate web site URL. I built several systems like this over the past few years, and they work non-stop relaying several thousand transmissions each day. I’ll post a picture of the boards and the little enclosure I put them in, but it’s all relatively simple and around $100.

If your logger location has Wifi, you could also just use a Wifi-bee module and send data directly to the web from the Mayfly. Or use a GPRSbee to send it via cellular.

As for the database, if you don’t have experience with SQL and HTML, it’s not simple to set up all the database stuff and the supporting web host and pages. That’s how I did it for the past 5 years with our original system, and it’s probably too complicated for most users. But we’ve been developing a new system at http://data.envirodiy.org where users can send their data to the site where it can be stored and can easily be seen with a time series viewer. We’re working on the documentation on how to write the Arduino code for how to send data to the site, but there should be some examples in our Github repository to get you started.

Here’s a couple photos of the UnoEthernet/Xbee receiver I built a long time ago. I has been running non-stop since February 2013 and receives about 4500 transmissions per day. With an average of 10 parameters per transmission, that’s 16.5 million parameters per year, so this little box has passed over 80 million parameters into my simple database in the past 5 years. I haven’t had to restart it do anything in the past 5 years except once when I had to update the IP address of the destination website nameserver when the host did some updates that resulted in a new address.

The Xbee module is a XbeePro 900Mhz and is mounted to an Xbee adapter board from Adafruit. I drilled holes in the case and bent the LEDs so that they poke through the case you can see the Xbee’s status. It’s held on to the case by the SMA jack of the XbeePro. It’s connected to a coax line that runs to the roof where we mounted a high-gain omnidirectional antenna.

This is what we use for receiving data from all of the stations within about a mile of our research lab. The rest of our dataloggers in other locations send data to the database via cellular modules with a $5/month cell plan from Hologram.io

We have more than 100 loggers streaming live data every 5 minutes, that adds up to around 9 million points per month and over 100 million points per year.

Here’s the code running on the UnoEthernet/Xbee shown above, but with the URL and IP addresses removed. I based this all from some examples I found about 6 years ago, so there’s probably better ways to do this nowadays.

As mentioned above, I use lots (100+) of GPRSbee modules, they are available from SODAQ in the Netherlands. They are 2G, so they only work in certain areas, but we find there’s coverage in about 90% of our locations. There are 3G and 4G bee modules available from other companies like Digi, but they cost at least twice as much so we usually just use the GPRSbees.

There’s a lot of things that could cause your data to now show up in the table, either on the Arduino end or the server/PHP end. Have you tried visiting the URL using your web browser to make sure you’re able to post data to the table using a properly formatted URL? If you can do it with a browser, then you know your PHP code is right and the issue is with your Arduino sketch. But if you can’t add data to the table via your browser, then you’ll need to fix your PHP code on the server.

The code I posted above is for the Arduino/Xbee receiver module. All it does is “visit” a URL that it “hears” on the radio. The Mayfly logger in the field is the unit that actually generates the rest of the URL. I put the beginning of the URL in the receiver code above just for simplicity, but in real life the entire URL is generated on the field loggers because sometimes they visit different PHP scrips or domains. If you have more than one logger sending data, you’re going to want to have different tables for each station. Then you have the parameters to send. So the logger payload that goes into “thisData” in the example would be a string that should look something like this: UnitId=001&Temperature=14.2&Voltage=2.5&Depth=342.5

And the full URL would be: https://www.somewebsite.com/demo.php?UnitId=001&Temperature=14.2&Voltage=2.5&Depth=342.5

Your PHP script would then put the 3 parameters into the table name designated by “UnitId”.

Where did you get that code example? It looks like a combination of some older code I used to use plus some newer stuff, but there are several mismatches and missing things so it won’t work properly as written. To transmit on an Xbee module, you should use Serial1. Serial0 is the port you should use for printing to the serial monitor. Your example above has all the status stuff happening on Serial1, so that should be changed to just Serial and then you can transmit the Xbee string payload on Serial1, since that’s the default configuration of the solder jumpers on the back of the Mayfly.

Once you have taken whatever sensor measurement you want, you can build a data record string append to the date/time/battery/boardtemp string and then write it to the memory card, and then also use those same variables to build the URL string in a separate function. Then just send that URL string to the Xbee serial port (assuming you’ve turned on the Bee module in advance, I use the pin-sleep configuration so I’m able to toggle the Beee module on and off).

Also, in your code above, the onboard battery voltage measurement part in the createDataRecord has the ratio as 1.47, which is only correct for Mayfly boards v0.3 and 0.4. For boards v0.5 and above, the ratio is 4.7. Which version of Mayfly do you have?

Most of your code looks familiar, though very mish-mash. I’m glad it works.

As far as getting the data into a website or MySql database… Doing that is all going to be the responsibility of your web receiver, that is, whatever website the internet connected radio receiver visits. You have to use your php or whatever set up for that.

Have you looked at the Wiki Watershed/EnviroDIY data portal? http://data.envirodiy.org/ If you are able/willing to have your data publicly viewable, you can take advantage of the structure already in place there to store/view/graph your data. We’ve also created a library to simplify sending data there from many different kinds of sensors, including the Maxbotix sonar sensors. https://github.com/EnviroDIY/ModularSensors. The communication with the data portal in this library is assumed to be via direct internet connection (cell/wifi) but you could also use most of the functionality and set it to another radio instead.