[Shannon Hicks]

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.

[Shannon Hicks]

Xbee modules plugged in to the Mayfly’s Bee headers communicate directly with the ATmega1284P processor’s secondary hardware serial port. So if you want to see any Bee traffic on your serial monitor, you’ll need to have a sketch running on the Mayfly that captures anything heard on “Serial1” and then print it to the monitor via Serial.

Likewise, if you want the Mayfly to transmit something via the Bee, you have to do that via “Serial1”.

[Shannon Hicks]

I got that connector from All Electronics: https://www.allelectronics.com/item/con-242/2-pin-connector-w/header-.10/1.html

Any 2-pin header with standard 0.1″ (2.5mm) spacing will work, though I prefer the ones from AllElectronics because they’re polarized and come with the prewired matching cable with 8″ leads. They’re made specifically for that company, so you can’t find them elsewhere.

Otherwise, you can use a basic Molex 2-pin polarized header, but then you’ll also need the mating jack and crimp pins.

[Shannon Hicks]

This wouldn’t be possible using the built-in solar chargers on the Mayfly board. But it would be possible to have one separate main 6v-12v battery and solar panel (with appropriate external solar charge controller), and then you could just connect both Mayfly boards to that one battery via the Mayfly’s “External 4-12v” jack. Something like a 6v SLA battery with a small panel and controller would be pretty cheap and would have plenty of capacity to power two (or more) Mayfly boards.

[Shannon Hicks]

We just received a big shipment of new Mayfly boards from the manufacturer yesterday, I tested a bunch today and boxed them up, so they’ll be on their way to Amazon tomorrow. You should see the boards available on Amazon next week sometime, with the kits available the week after that. We had a lot of orders right before the holidays that drained our Amazon stock, so we didn’t know they’d all sell out so quickly.

[Shannon Hicks]

After a Mayfly workshop earlier this week, I helped 2 people install the IDE and Mayfly drivers on their Macs, using the latest Arduino IDE and by following the directions on this site, and it went smoothly with no issues. Are you just not seeing the EnviroDIY boards listed when you choose “Contributed”? If you’ve pasted the URL properly into the box on the IDE your preference tab, it should work.

[Shannon Hicks]

What version of the Mayfly board do you have? The newer boards have a different regulator than earlier versions, so make sure you’re looking at the right datasheet and resistors.

If you’re comfortable removing and reinstalling SMT resistors, then it is possible to remove that resistor and replace it with another one to achieve different output voltages. But you have to be careful with supplying 12v to external devices so that you don’t exceed the maximum safe current and that the return data is at a safe voltage, otherwise you’ll damage the Mayfly. It’s likely you might need some external level shifters on the return data lines, which is why I didn’t include 9v and 12v excitation options on the Mayfly to begin with. Things can quickly go bad if users aren’t careful about voltage levels, so I decided to keep higher voltage stuff off the Mayfly. You can add an external boost regulator for just a few dollars each (5, 9 or 12v) from here: https://www.pololu.com/product/2117

Then you can put that boost regulator on a Grove protoshield (https://www.robotmesh.com/grove-protoshield) along with a level-shift breakout and then a header or screw terminal, and then you’ll have everything you need for safely powering an external device with a different voltage.

[Shannon Hicks]

ChanCafun is right, you definitely don’t want to connect any panel to the Mayfly’s SOLAR jack that has a voltage higher than 6 volts. I wrote a post about solar panel options earlier this year: https://envirodiy.org/topic/dying-batteries-in-winter/#post-2051

Since that post, we’ve released the Mayfly v0.5 that has the option for directly connecting up to 16v on the External Power input pins. But unless you’re leaving the logger on continuously and powering some current-hungry sensors, you should be fine with a 3.7v Lipo paired with a 3.5W, 6W, or 9W panel, keeping in mind that anything over 3W is unnecessary if you’re in direct sunlight (see my explanation in the post above).

[Shannon Hicks]

The code I posted above is for when you use a ADS1115 16-bit ADC. If you’re using a standard Uno or Mega board, you’ll have to use the regular 10-bit ADC, unless you’re planning to use a separate ADS1115 breakout. But assuming you’re okay with the lower resolution of the 10-bit ADC, just use the standard analogRead command and then convert the result to voltage. And because the output of the SP-212 is 1mv = 1 PAR, the measured voltage (in millivolts) is the PAR. The 10-bit resolution of the ADC means you’ll get steps of around 5 PAR (4.89 actually).

Arduino

void setup(void) { Serial.begin(9600); } void loop(void) { int sensorValue = analogRead(A0); //change this to the correct analog pin you're using float voltage = sensorValue * (5.0 / 1023.0); //converts bits to volts float PAR = voltage * 1000.0; //converts volts to PAR (for SP-212, 1 mV = 1 PAR) Serial.print("Bits: "); Serial.print(sensorValue); Serial.print(" PAR: "); Serial.println(PAR); delay(1000); }

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void setup(void) {   Serial.begin(9600); }   void loop(void) {   int sensorValue = analogRead(A0);  //change this to the correct analog pin you're using   float voltage = sensorValue * (5.0 / 1023.0);  //converts bits to volts   float PAR = voltage * 1000.0;   //converts volts to PAR (for SP-212, 1 mV = 1 PAR)   Serial.print("Bits: "); Serial.print(sensorValue);   Serial.print("     PAR: ");  Serial.println(PAR);   delay(1000); }

[Shannon Hicks]

We designed the Mayfly logger system to be very easy to build and deploy. In fact, we’ve been teaching workshops to school groups and citizen scientist programs for the past year and I was actually in Grand Forks, ND earlier this summer where we gave a 2-day workshop at UM-Crookston. With most of our school workshops, we taught middle-school and high-school students some basics of electronics and coding/programming, and then we gave them kits and let them build a logger, assemble everything in the waterproof enclosure, and then show them the tips and techniques needed to successfully deploy the station in a stream. We also talk about maintenance and troubleshooting and how to QA/QC the collected data, and and some general scientific background to help them understand why we’re collecting the data and what the different parameters (turbidity, conductivity, pH) mean in the big picture. This was all part of a pilot program from the EPA to develop workshop materials and teaching curriculum based on the Mayfly board and various sensors. If you’d like, we could send you some of the information when it’s published.

And as for the circuit boards themselves, they are very simple to use. We can supply the code you need to program the board for most logging deployments (most of it is already available on our Github page), and almost all sensors simply connect to the board with simple jacks or screw terminals, so there’s no soldering or electrical engineering background needed. It gets powered by a small LiPo battery with a small solar panel to keep it continuously charged. The hardest part is making sure the enclosure you mount the sensors in is waterproof, and that you install the sensors in the water in a way that gives reliable data and can withstand floods/ice/mud etc. We use a variety of sensors from low-cost short-term deployable sensors to rugged research-grade sensors that require much less maintenance but cost several times more. So choosing the sensors really depends on your budget, how often you want to maintain them, and the quality of data you want to record. Using the Mayfly is not much harder than any other modular logger/sensor station you could build from other, more expensive commercial hardware options. In the end, you’ve still got to protect a logging device from the weather by putting it in some sort of enclosure along with a source of power, then mount your sensors and hope they can survive whatever flood events will eventually happen. The Mayfly significantly lowers the entry cost for building a station, plus you can use just about any sensor you want from any manufacturer without worrying that it isn’t compatible with a different brand. Plus you can use the Mayfly for any other regular Arduino-type microcontroller project, so it is a very versatile little circuit board.

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