[Shannon Hicks]

The sleeping sketch I mentioned above works fine as long as you don’t use the SDI12 library at the same time. If you do, there’s some conflicts due to the SDI12 and SODAQ_Pcint libraries looking at the same ports. So I created modified versions of both libraries that fixes the conflict. (This conflict also happens if you use SoftwareSerial and Pcint at the same time, so I also made a modified version of SoftwareSerial.) It’s kind of a brute force fix and there’s probably a better way, but it gets the job done.

If you don’t already have all of the libraries I posted recently (https://github.com/EnviroDIY/Libraries) get them and then simply change the include statements at the top of your sketch to look like this:

Arduino

#include <Sodaq_PcInt_Mod.h> #include <SDI12_Mod.h>

1 2	#include <Sodaq_PcInt_Mod.h> #include <SDI12_Mod.h>

You don’t have to change anything else in your sketch, the modified libraries will handle everything the same.

[Shannon Hicks]

“20V-1A” is just the rating of the protection diode on the PC board. When choosing a solar panel for the Mayfly, you should only connect ones that are listed as 6 volt panels, and do not use a 9-volt or 12-volt panel.

[Shannon Hicks]

The charging circuitry on the Mayfly isn’t capable of charging 2 parallel battery packs simultaneously, so it’s not advised to connect two packs to the Mayfly if you ever connect a mucroUSB cable or solar panel to it because either of those will start the charging process.

The second LIPO connector on the Mayfly is for providing a direct connection to the battery for high-current accessories like a GPRSbee module. It’s not supposed to be used to provide a secondary battery input for the Mayfly.

However, if you take precautions to make sure you never connect a microUSB or solar panel, then theoretically it’s possible to connect two parallel batteries to power the Mayfly, but you run into the usual issues related to parallel battery operation, like making sure both batteries have identical capacity and are charged to the same initial voltage, along with other precautions. Given the dangers of short-circuiting LIPO batteries and causing a fire, EnviroDIY does not recommend that users connect more than one battery to their Mayfly at a time.

Also, if you connected 2 LIPO batteries at once, you can’t use the onboard LIPO charging circuitry on the Mayfly, so there’s no benefit to using LIPO batteries and you might as well just use a single high-capacity battery pack of a different chemistry (like lead acid or alkaline) if you’re looking for longer lifespan.

[Shannon Hicks]

The sample code above will not work properly until you’ve correctly changed the channel number for each of the 6 sensors. Also, once you do that and you have a different number of sensors other than 6, you’ll need to change the number in line 31 to the correct number of sensors.

So first you should make sure you change the channel number of one sensor at a time and then verify that the sample code for reading one sensor works properly before proceeding further.

To connect a Decagon 5TM probe to your Arduino board, connect the sensor bare braided wire to a ground pin of the Arduino. Connect the white sensor wire to 5V, and connect the red sensor wire to the data pin (pin D7 in the example above).

[Shannon Hicks]

It’s not currently available in Europe, but we’re working on it!

[Shannon Hicks]

The circuit components are rated to the industrial temperature range of -40C to +85C, but I think at extreme temperatures you’re more likely to encounter problems with your battery rather than the Mayfly circuit. LiPo batteries don’t perform well at either really cold or really hot temperatures, so you might consider a different type of battery chemistry if you’re deploying it long-term in a harsh environment.

Last winter, a number of my Mayfly loggers saw -20 degrees on a number of occasions according to the logged temperature of the onboard DS3231.

[Shannon Hicks]

Here’s some sample code for running 6 Decagon 5TM probes with a standard Uno board. It could be modified by changing the pin number for the LED, in the example below I used the default pin 13 for the onboard LED. Mayfly users would want to select either 8 or 9. I usually prefer to do long-time recording with a separate real-time-clock module like what’s on the Mayfly, but in this example I just polled the rolling “millis” counter to get the time since the board was started. I set the example interval to 60 seconds, but you could adjust that if you wanted.

Remember that first you have to connect each 5TM sensor to the Arduino board one at a time and configure each one with a unique channel number. To work with the code below, you should number them sequentially from 1 to 6. Use the “address change” example that’s included with the SDI12 library, making sure to hook the sensor data pin to the correct pin that’s stated in the example, or change the example to match your wiring. In my example code below, I put the sensor data pin on D7.

I think this code should work, it compiles properly, I just don’t have 6 sensors handy to test it completely. It’s based on some thoroughly-tested Mayfly code, but I just removed all of the code regarding the Mayfly’s RTC, memory card, and sleeping functions.

Arduino

#include <SDI12.h> #define DATAPIN 7 // change to the proper pin for sdi-12 data pin, I prefer D7 SDI12 mySDI12(DATAPIN); unsigned long previousMillis = 0; const long interval = 60000; //set the interval (in milliseconds). ex: 60000 = 60 seconds void setup () { pinMode(13, OUTPUT); digitalWrite(13, LOW); //turn off the onboard LED to start with Serial.begin(57600); mySDI12.begin(); Serial.println("Sketch for sampling multiple SDI12 sensors"); delay(1000); } void loop () { unsigned long currentMillis = millis(); if(currentMillis - previousMillis >= interval || previousMillis == 0) { previousMillis = currentMillis; digitalWrite(13, HIGH); //turn on the onboard LED to show that samples are being taken Serial.print("Time: "); Serial.print(currentMillis/1000); //print out the current time, in seconds Serial.print(" ---- "); for (char j = '1'; j <= '6'; j++) { //go through channels 1 to 6 tmMeasurement(j); } Serial.println(); digitalWrite(13, LOW); //turn off the LED to show that samples are done } delay(1000); } void tmMeasurement(char c){ //5TM soil moisture sensor String command = ""; float Ea = 0.0; float temp = 0.0; float VWC = 0.0; command += c; command += "M!"; // SDI-12 measurement command format [address]['M'][!] mySDI12.sendCommand(command); delay(500); // wait a sec mySDI12.flush(); command = ""; command += c; command += "D0!"; // SDI-12 command to get data [address][D][dataOption][!] mySDI12.sendCommand(command); delay(500); if(mySDI12.available() > 0){ int channel = mySDI12.parseInt(); Ea = mySDI12.parseFloat(); temp = mySDI12.parseFloat(); VWC = (4.3e-6*(Ea*Ea*Ea)) - (5.5e-4*(Ea*Ea)) + (2.92e-2 * Ea) - 5.3e-2 ; //the TOPP equation used to calculate VWC Serial.print("Sensor:"); Serial.print(channel); Serial.print(": Ea="); Serial.print(Ea); Serial.print(", VWC="); Serial.print(VWC); Serial.print("%, Temp="); Serial.print(temp); Serial.print("degC .... "); } mySDI12.flush(); }

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79

#include <SDI12.h>   #define DATAPIN 7         // change to the proper pin for sdi-12 data pin, I prefer D7 SDI12 mySDI12(DATAPIN);   unsigned long previousMillis = 0;         const long interval = 60000;        //set the interval (in milliseconds).  ex: 60000 = 60 seconds   void setup () {      pinMode(13, OUTPUT);      digitalWrite(13, LOW);    //turn off the onboard LED to start with      Serial.begin(57600);      mySDI12.begin();      Serial.println("Sketch for sampling multiple SDI12 sensors");      delay(1000); }   void loop () {     unsigned long currentMillis = millis();     if(currentMillis - previousMillis >= interval || previousMillis == 0) {           previousMillis = currentMillis;          digitalWrite(13, HIGH);     //turn on the onboard LED to show that samples are being taken        Serial.print("Time: ");        Serial.print(currentMillis/1000);  //print out the current time, in seconds        Serial.print(" ---- ");               for (char j = '1'; j <= '6'; j++)  {        //go through channels 1 to 6          tmMeasurement(j);          }               Serial.println();        digitalWrite(13, LOW);     //turn off the LED to show that samples are done      }           delay(1000);      }   void tmMeasurement(char c){        //5TM soil moisture sensor   String command = "";   float Ea = 0.0;   float  temp = 0.0;   float VWC = 0.0;   command += c;   command += "M!"; // SDI-12 measurement command format  [address]['M'][!]   mySDI12.sendCommand(command);   delay(500); // wait a sec   mySDI12.flush();     command = "";   command += c;   command += "D0!"; // SDI-12 command to get data [address][D][dataOption][!]   mySDI12.sendCommand(command);   delay(500);        if(mySDI12.available() > 0){         int channel = mySDI12.parseInt();         Ea = mySDI12.parseFloat();         temp = mySDI12.parseFloat();         VWC = (4.3e-6*(Ea*Ea*Ea)) - (5.5e-4*(Ea*Ea)) + (2.92e-2 * Ea) - 5.3e-2 ;     //the TOPP equation used to calculate VWC              Serial.print("Sensor:");       Serial.print(channel);       Serial.print(": Ea=");       Serial.print(Ea);       Serial.print(", VWC=");       Serial.print(VWC);       Serial.print("%, Temp=");       Serial.print(temp);       Serial.print("degC  ....  ");           }   mySDI12.flush(); }

[Shannon Hicks]

You’re going to need to connect the sensors one at a time to the Arduino board in order to program the address. Then you’ll need to hook them all together to the same bus. For example, all 6 of the sensor power wires need to go to the Vcc power bus, all 6 of the sensor ground wires need to go to the board GROUND, and all 6 of the sensor data lines need to go to a data pin (I like to use D7 for my SDI-12 data lines because it’s rarely used by other things like accessory shields).

So your challenge is going to be getting 3 sets of 6 wires all connected to just 3 pins on the Arduino board. This can be accomplished in a variety of ways, depending on how comfortable you are with soldering or stripping wires or making a custom board with some screw terminals. Or you might be able to do it with a breadboard if you don’t mind cramming the sensor wires into the holes (it’s generally bad practice to cram medium-gage bare wires into a solderless breadboard because it permanently widens the contacts making it unreliable for later use with smaller components).

Do you have a breadboard, or some spare screw terminals, or a screw-terminal breakout shield for the Duemilanove? Or maybe you just want to use a wire nut to join each of the 6 wires together along with one wire to connect to Arduino board? It’s usually not recommended to join that many wires with one wire nut, but it might be possible if you do it just right. Is this just for a temporary test/experiment, or are you thinking of a long term setup?

Once we figure out the wiring, I can post the sample code for cycling through 6 channels. How often do you want to take a sample, and is it just being displayed on the computer using the Arduino IDE’s serial monitor? If you used a Mayfly the data could also be time-stamped and stored on the memory card.

[Shannon Hicks]

I’ve connected 15 of the Decagon 5TM sensors to one Mayfly board before, so it’s no problem to connect 6 to a Duemilanove. You’ll need to figure out how to get them all wired to the board, and that depends on what type of termination is on the ends of the sensors. Do your 5TM probes have the 3.5mm stereo headphone-type jack on the ends, or are they bare wires?

[Shannon Hicks]

Did you use the “Address Change” example included with the SDI12 library to give each sensor a unique address? Decagon 5TM sensors are always set to default address “0” when you first use them, so you’ll need to select new ones. I’d suggest something sequential like 1, 2, 3, etc so that it’s easy to cycle through them in the sampling code. How many sensors are you connecting at once? And are you using these with a Mayfly board or some other sort of hardware arrangement?

[Author]

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