[Shannon Hicks]

Can you describe how you’ve connected the sensors to your Mayfly, there are multiple ways to do it correctly with the adapters we offer and even more if you’re doing it a non-traditional way.  Better yet, could you take a pictures of your setup showing how you’ve connect each of the sensors to the Mayfly?

[Shannon Hicks]

When the sensor is powered, you should be able to put the two probes of a voltmeter on the little screws on top of the screw terminal board where you’ve connected the ClariVue’s cable to the Mayfly.  Put the black probe on the Gndscrew and the red probe on the V+ screw.   You’ll know the sensor is being powered when the red LED on the bottom left corner of the Mayfly board is lit  (the one labeled Switched Power Out).  You can put the Mayfly into test mode by pressing (for one second) the D21 pushbutton next to the microSD card socket.  That’ll wake the Mayfly (and keep it awake) for a few minutes, constantly keeping the output power on and will also output sensor data to the serial monitor every 10 seconds or so.  Putting it in this mode will give you time to check the output voltage with a meter.

[Shannon Hicks]

The calibration sheet from Turner was very accurate for the new sensor, so if you don’t want to buy expensive rhodamine standard right now, you’re probably fine to use the data from the sheet.  But we’ve found that the sensors tend to drift over time so we do quarterly recalibrations of the sensors to make sure they’re still accurate.

Here’s a simple sketch to take 100 analog readings quickly and average them, then constantly repeat that, and printing all data to the serial port.  Then I just copy/paste the text from the serial port into Excel so I can do an analysis and overall average.

Arduino

//Takes lots of readings from the EnviroDIY Mayfly's ADS1115 Aux Analog ADC and averages them, prints to screen #include <SPI.h> #include <Wire.h> #include <Adafruit_ADS1015.h> Adafruit_ADS1115 ads; // The Mayfly's ADS1115 Aux ADC is 16-bit version float average_volts; //variable to hold the calculated average int State8 = LOW; int State9 = LOW; int aux_channel = 0; //channel number of whatever pin you've got your input connected to for the ADS1115 Aux Analog chip (AA0 = 0, AA1 = 1, AA2 = 2, AA3 = 3) int readcount = 100; //the number of readings you want to take for each sample int time_between_readings = 10; //number of milliseconds between each reading in a sample void setup() { Serial.begin(57600); //Start the serial connection with the computer ads.begin(); //begin adafruit ADS1015 pinMode(8, OUTPUT); // define the red and green LEDs as outputs pinMode(9, OUTPUT); digitalWrite(8, HIGH); //turn on one of the LEDs to start with digitalWrite(9, LOW); pinMode(22, OUTPUT); //switched power pin declared as output digitalWrite(22, HIGH); //turn on the Switched sensor voltage Serial.println("EnviroDIY Mayfly Aux-Analog Averaging Sketch "); Serial.print("Aux ADC Channel: "); Serial.print(aux_channel); Serial.print("(AA"); Serial.print(aux_channel); Serial.print(") Number of readings per sample: "); Serial.println(readcount); Serial.println("-------------------------------------------------------------"); delay(2000); //wait 2 seconds } void loop() { auxanalog_sample(); //go take a measurement with the ADS1115 //blink the red and green LEDs in alternating fashion on each loop if (State8 == LOW) { State8 = HIGH; } else { State8 = LOW; } digitalWrite(8, State8); State9 = !State8; digitalWrite(9, State9); // Serial.print("Averaged analog voltage (volts): "); //print the results to the serial monitor Serial.println(average_volts,5); delay(100); //wait a little bit between loops, adjust as you want } //end loop void auxanalog_sample() // function that takes reading from ADS1115 Aux Analog chip on Mayfly { int16_t adc_bits = 0; //int to hold the value of the bits that get read float bit_sum = 0.0; //sum of all the bits read for (int i = 0; i < readcount; i++){ adc_bits = ads.readADC_SingleEnded(aux_channel); //take a single-ended reading with the ADS1115 bit_sum += adc_bits; //add the latest reading to the sum delay(time_between_readings); //wait x milliseconds between readings, adjust as you want } float average_bits = bit_sum / readcount; //find the average by dividing the bit_sum by readcount //now convert bits into volts //average_volts = (average_bits * 3.3)/17585.0; // use this next line instead of the previous line if you're using a voltage divider to reduce an external sensor's voltage average_volts = ((average_bits * 3.3)/17585.0) * 2.0; //multiply by 2 if you used a 50/50 divider }

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//Takes lots of readings from the EnviroDIY Mayfly's ADS1115 Aux Analog ADC and averages them, prints to screen   #include <SPI.h>           #include <Wire.h>           #include <Adafruit_ADS1015.h>   Adafruit_ADS1115 ads;     // The Mayfly's ADS1115 Aux ADC is 16-bit version   float average_volts;   //variable to hold the calculated average int State8 = LOW; int State9 = LOW;   int aux_channel = 0;  //channel number of whatever pin you've got your input connected to for the ADS1115 Aux Analog chip (AA0 = 0, AA1 = 1, AA2 = 2, AA3 = 3) int readcount = 100;  //the number of readings you want to take for each sample int time_between_readings = 10;  //number of milliseconds between each reading in a sample   void setup() {   Serial.begin(57600);  //Start the serial connection with the computer   ads.begin();       //begin adafruit ADS1015     pinMode(8, OUTPUT);    // define the red and green LEDs as outputs   pinMode(9, OUTPUT);       digitalWrite(8, HIGH);   //turn on one of the LEDs to start with   digitalWrite(9, LOW);     pinMode(22, OUTPUT);     //switched power pin declared as output   digitalWrite(22, HIGH);  //turn on the Switched sensor voltage            Serial.println("EnviroDIY Mayfly Aux-Analog Averaging Sketch ");   Serial.print("Aux ADC Channel: ");   Serial.print(aux_channel); Serial.print("(AA"); Serial.print(aux_channel);   Serial.print(")   Number of readings per sample: ");   Serial.println(readcount);   Serial.println("-------------------------------------------------------------");     delay(2000);  //wait 2 seconds    } void loop()                   {      auxanalog_sample();     //go take a measurement with the ADS1115       //blink the red and green LEDs in alternating fashion on each loop     if (State8 == LOW) {       State8 = HIGH;     } else {       State8 = LOW;     }     digitalWrite(8, State8);         State9 = !State8;     digitalWrite(9, State9);       // Serial.print("Averaged analog voltage (volts):  ");  //print the results to the serial monitor     Serial.println(average_volts,5);       delay(100);  //wait a little bit between loops, adjust as you want   }   //end loop     void auxanalog_sample()     // function that takes reading from ADS1115 Aux Analog chip on Mayfly { int16_t adc_bits = 0;       //int to hold the value of the bits that get read float bit_sum = 0.0;        //sum of all the bits read   for (int i = 0; i < readcount; i++){     adc_bits = ads.readADC_SingleEnded(aux_channel);   //take a single-ended reading with the ADS1115     bit_sum += adc_bits;    //add the latest reading to the sum     delay(time_between_readings);   //wait x milliseconds between readings, adjust as you want   }     float average_bits = bit_sum / readcount;  //find the average by dividing the bit_sum by readcount   //now convert bits into volts   //average_volts = (average_bits * 3.3)/17585.0;     // use this next line instead of the previous line if you're using a voltage divider to reduce an external sensor's voltage    average_volts = ((average_bits * 3.3)/17585.0) * 2.0;  //multiply by 2 if you used a 50/50 divider    }

 

[Shannon Hicks]

Both of those sensor models ship from their manufacturers with their SDI12 address set to ‘0’ (zero).  In order for the Hydros21 sensor to work with the Mayfly logger in SDI12 mode, you MUST change the address of the sensor to anything other than zero (otherwise the sensors is in TTL output and not SDI12).  It’s okay for the ClariVue sensor to remain at channel 0, but your logging sketch should agree with whatever you’ve set it to, and your sketch says 2, so you’ll need to use the address-changing sketch to set the channels.  Note that you can’t connect both new sensors at the same time when setting the channel.  Only connect one sensor to the Mayfly when doing the address changing procedure.   Once you’ve got one sensor connected, the sketch will cycle though all 62 possible channels.  If it’s not stopping on zero (or maybe another channel if you’ve been able to successfully change the channel earlier), then that means your logger doesn’t hear anything from the sensor.  If that’s the case, then your wiring to the Mayfly may be wrong or something else.  Are you supplying 12v to the ClariVue sensor using a screw terminal board (either directly from the Mayfly’s onboard 12v option or the external 12-v boost screw terminal board)?  The Hydros21 works fine at 3.3v or 5v or 12v.   If you’re using the 3.5mm stereo plug option, make sure it’s plugged firmly into the jack on the Grove adapter board.  If you’re using bare wires, make sure you’ve got the 3 wires from the sensor connected to the proper screw terminals (Ground, V+, and S2).

[Shannon Hicks]

I assume you are using a Mayfly v1.1 board and not an older v1.0, because it had a hard time providing a stable 12v for that particular type of sensor.  But are you using the onboard 12v source by selecting 12v on the Grove voltage selector jumper, or are you using one of the new screw terminal boards that has its own 12v boost circuit on it?  And have you put a voltmeter on the power wires going to the sensor when it’s on to verify that it’s receiving 12volts?

[Shannon Hicks]

That all looks correct.  I usually put the Mayfly’s analog Grove jack voltage selector jumper to the 5v position because the old sensors required 5v for excitation, but supposedly these newer ones are happy with 3v to 15v, but we still use them at 5v and calibrate them with that excitation voltage.  If you connect the 6-pin screw terminal board shown in your photo to the Mayfly’s upper aux analog jack (AA0-AA1), then your sensor will be connected to the A0 pin, so make sure that’s what you’ve entered on the line of your sketch that looks like this:

const int8_t cyclopsChloroADSChannel = 0; // ADS channel

We’ve only used the C-FLUOR sensors for phycocyanin but I would assume their operation and performance would be the same for the chlorophyll model.  Which one are you using?     The ModularSensors library for the Cyclops sensors assumes you’ll be entering the two voltages of the sensor output (blanking voltage and standard concentration voltage), and the concentration of the standard.  So for my station, it looks like this:

Arduino

// Cyclops calibration information const float cyclopsChloroStdConc = 40.000; // Concentration of the standard used // for a 1-point sensor calibration. const float cyclopsChloroStdVolt = 1.155488; // The voltage (in volts) measured for the conc_std. const float cyclopsChloroBlankVolt = 0.020348; // The voltage (in volts) measured for a blank.

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// Cyclops calibration information const float cyclopsChloroStdConc = 40.000; // Concentration of the standard used                                           // for a 1-point sensor calibration.   const float cyclopsChloroStdVolt = 1.155488; // The voltage (in volts) measured for the conc_std. const float cyclopsChloroBlankVolt = 0.020348; // The voltage (in volts) measured for a blank.

These voltages were obtained by placing the sensor (with power applied) in nanopure water (or distilled if that’s all you’ve got) in a large dark contained (a black opaque 1-liter bottle) and measuring the output voltage of the sensor.  Then we repeat it with 1 liter of the standard (the Rhodamine standard purchased from Turner).  If you’re measuring the voltage with an external voltmeter, remember that you’ll need to divide the voltmeter voltage by 2 because you’ve got that resistor-divider circuit on your screw terminal board.  So if you put the sensor in the standard and get 2.2 volts, you would then enter 1.1 volts into the sketch.  Same thing for the blanking voltage (although it’s usually a really small number closer to zero.)  We usually measure the voltage out to 5 decimal places using the Mayfly to measure the analog voltage 100 times (20 milliseconds apart) and take an average, then do that at least 50 more times, and take an average of all those measurements.

If you’ll be entering the data from the sensor’s calibration sheet instead, you’ll need to enter blanking voltage from the sheet (again, dividing by 2 because of the res-div).   So let’s pretend the datasheet says the blanking offset is 0.02 volts, so divide that by 2 and get 0.01.   And then the sheet gives you the calibration coefficient as ppb per volt (parts per billion per volt).  So pretend a sensor’s datasheet said 1035.4234 ppb/v.  So you could enter that number in the concentration line and 0.5v for the voltage (because that’s half of one volt), like this:

Arduino

const float cyclopsPhycoStdConc = 1035.4234; // Concentration of the standard used // for a 1-point sensor calibration. const float cyclopsPhycoStdVolt = 0.5; // The voltage (in volts) measured for the conc_std. const float cyclopsPhycoBlankVolt = 0.01; // The voltage (in volts) measured for a blank.

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const float cyclopsPhycoStdConc = 1035.4234; // Concentration of the standard used                                          // for a 1-point sensor calibration. const float cyclopsPhycoStdVolt =    0.5; // The voltage (in volts) measured for the conc_std. const float cyclopsPhycoBlankVolt =    0.01; // The voltage (in volts) measured for a blank.

 

[Shannon Hicks]

The file is there.  Is your computer behind a firewall that is blocking github?  What happens if you click on the link for the EnviroDIY json file?  You should see a simple text webpage with some code talking about packages and platforms.

[Shannon Hicks]

Can you email me your code at mayfly@envirodiy.org so I can take a look at it?  How many other adafruit ADC boards do you have attached to the Mayfly in question and are they the 12-bit or 16-bit versions?  The Mayfly’s ADC is permanently set to 0x48.  What is the typical and maximum voltages you should see on the sensor?

[Shannon Hicks]

The two sensor models perform exactly the same.  We’ve used a couple in the field with existing loggers when replacing some old broken Cyclops 7f sensors.  All we did was swap the sensors and redo the calibration and edit the appropriate 2 lines in the code for the voltage measured in the standard and the blank (nanopure water).  The C-FLUOR sensors do come with a calibration voltage on a datasheet in the package, but we prefer to do our own, plus we recalibrate them in the field periodically once deployed.  We use a rhodamine standard we purchased from Turner.   So you can just use the existing ModularSensors Turner Cyclops library.   Keep in mind that the sensors output a 0-5v analog signal, so you’ll need to use a resistor-divider to read them properly with a Mayfly logger.  Our new multipurpose screw terminal board has that option if you add your own resistors and change the solder jumpers on the back of the board.

[Shannon Hicks]

Can you email me the entire .ino sketch that you’re using with the board, and also a clear, in-focus photo of the back of the Mayfly board, and the front of the Mayfly board, with and without the LTEbee attached.

[Author]

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