[Shannon Hicks]

Mayfly v1.0RevA had a Max17250 boost chip that used the following resistors in order to set the output voltage at 12 volts:

R15 = 10k
R19 = 84.5k
R31 = 220k

When it was time to manufacture more boards in 2021, there was a semiconductor shortage that made it impossible to find that particular boost converter, so the design was modified to use a MCP1665 instead.  However, the first small run of Mayfly v1.1RevA boards used the resistors above from the previous circuit instead of the correct values below:

R15 = 20k
R19 = 180k
R31 = 470k

The input power selection options for the MCP1665 also didn’t behave like the Max17350 did, so before we shipped out any Mayfly boards from that run, I put a blob of silicone conformal coating on the back of the boards to cover SJ26 to make it unusable and also made a note about it on the schematic.  I also manually soldered a tiny black wire onto each board to connect the power circuit properly, as denoted by the blue line in the schematic and shown in the attached photo below.

So when it came time for the next production run, we opted to call it v1.1RevB since it would correct the problem with the incorrect resistors, add a trace to connect power circuits properly (to take the place of the black wire), and remove solder jumper SJ26 from the back of the board since it was no longer needed.  We also switched the ICSP connector from a small 2×3 0.5mm pitch header to a Tac-connect connector.

Someone asked this question about version differences a few years ago on the Technical Questions thread, and you can see my specific response here.

So in summary, the schematic currently on the website for v1.1RevA was what we designed, however the 3 resistor values placed by the manufacturer are different than specified in the documentation.  This affected only a small number of boards because we quickly made a new production run for v1.1RevB.  However not all of the documentation in various locations got updated with the latest specs.  I’ll go back and add a note to the v1.1RevA schematic to clarify which resistors were actually used on that batch, and will also update the Details and Specs page to more clearly state the specs of the current v1.1RevB board.

Attachments:

1. 

   v1p1revA_jumper-rotated.jpg
   

[Shannon Hicks]

In 2021, there was one small production run of the Mayfly v1.1 RevA boards that, due to an error by the manufacturer, used an incorrect resistor value for the 12-volt boost circuit, resulting in a lower output voltage, around 11.3v.  This was corrected in the next manufacturing run, along with making a few other changes, which is why the v1.1 RevB version came out in early 2022.  There were notes on the product websites (here and Amazon) at the time the RevA boards were for sale, stating that the 12v output was lower than ideal.  We also designed and built the 12-volt Boost Screw Terminal Grove Adapter at that time so that people could use that to generate a proper 12-volt supply for sensors that might be sensitive to the 11.3v directly from the board.  It’s also useful for people who still have a Mayfly 0.5v or earlier version, allowing them to generate 12v (or 9v) because those older boards only had onboard 3v and 5v output.   Any of the v1.1 RevB boards that have been available since mid-2022 generate the proper voltage with the onboard 12v boost circuitry.

[Shannon Hicks]

There’s a section in the User Manual that should have been included in the shipment with your sensor (it’s also downloadable from here: https://metergroup.com/products/teros-12/teros-12-support/) that explains how to use the raw number collected by the sensor to calculate soil moisture content.

 

[Shannon Hicks]

It looks like you’re having the same issues a few other people have reported lately. We’re working on a fix, but in the meantime, the easiest thing to do is to replace all your “MyDocuments/Arduino/libraries” files with the stable versions from last summer.  In order to do this, you’ll have to delete all the current library files on your PC.  If you’re only using a Mayfly board with the standard sensors and accessories we typically recommend, and you haven’t downloaded other library files for other non-EnviroDIY devices or equipment, then it’s fine to delete all your library files.  If you HAVE downloaded other non-EnviroDIY library files for other things, then don’t proceed because you’ll delete the files for those other things.  Otherwise, follow these instructions:

First, close the Arduino IDE (it’s best to do this without the IDE running).  Then use Windows File Manager (assuming you’re on a windows PC) to browse to MyDocuments/Arduino.

In there you’ll see any customized sketches you’ve saved, plus a folder called “libraries”

Double click on “libraries”, and in that folder you should see about 45 folders (if you’re using the most recent version of ModularSensors and it’s dependencies).  Highlight them all (using Ctrl+A) and then hit Delete key (or right click on them with the mouse and choose Delete).

Now you should have a libraries folder that is completely empty.

Now use your browser to visit this page: https://github.com/EnviroDIY/ModularSensors/releases

Scroll down to the May 17, 2024 entry which is for version v.0.35.0

At the bottom of that section, click on “Assets” and you should see 3 files listed.  Right-click on the one called “ModularSensors_Dependencies_v.0.35.0.zip” and save the file to your computer.

Now use windows File Manager to double-click on that zip file.  Inside it you should see 32 folders.  Select all of them, hit Ctrl-C to copy (or right-click and Copy).  Then switch to the empty “libraries” folder within your “MyDocuments/Arduino” folder, and paste the 32 directories into the libraries folder.

You have now installed the old, stable versions of the library files.  Restart your Arduino IDE and you should still have all your saved personal sketched in the Sketchbook, and when you compile the sketch for your logger, you should have no errors now.

[Shannon Hicks]

That means your IDE’s Serial Monitor baud rate is not the same as the baud rate in your sketch

[Shannon Hicks]

Did you make sure the sensor is properly wired to your Mega, (tip to 5v, sleeve to GND, and ring to data) and that the pin number in the sketch matches whatever pin number you connected the data line to?  If all the wiring is correct, then it might be an issue with the latest SDI12 library that a few people have reported.  You could try replacing all of the latest SDI12 library files you downloaded (the entire folder) and replace it with a stable legacy version (v2.1.4) from a few years ago (https://github.com/EnviroDIY/Arduino-SDI-12/tree/v2.1.4) and see if that fixes it.

[Shannon Hicks]

The baud rate in the example sketches is usually 57600 or 115200, which is the rate for the Arduino board’s serial output port that it uses to communicate with your computer, not the sensor.  For whatever rate you choose, you have to manually change your IDE’s baud rate to match, otherwise you’ll just get gibberish on the monitor.  The baud rate of the SDI12 sensor port (pin 7 in most examples because of how the Mayfly board is wired) is hard-coded to 1200 in the library files and can’t (or shouldn’t) be easily changed by end users.

If you use a Meter sensor on a Meter logger, it MUST be set to channel 0.  Their logger will not communicate with any sensor that has an address other than 0.  So if you change your sensor address to 1 (or A, or x, or any other valid SDI12 address) to use with your Arduino board, in the future if you want to put that sensor on a Meter brand logger, you’ll have to use your Arduino board and the b_change_address sketch again to change it back to 0.  Alternatively, if you think you’ll be doing this switching a lot, it would be worth it to get one of the ZSC modules from Meter.  It’s a low cost device that uses a bluetooth connection and an app on your phone to read and configure Meter sensors.  It’s great for reading live sensor data and changing SDI12 addresses.

[Shannon Hicks]

I’ve attached a screenshot from Meter Group’s Teros 12 Integrator Guide.  It shows the wiring scheme for the bare-wire version and the 3.5mm stereo plug version.  If you’ve got the sensor with the 3.5mm plug, then you’ll need to compare this diagram to whatever breakout board you’re using to match the tip, ring, and sleeve to the power, ground, and data lines.

Then you can connect those 3 lines to whichever board you’re using.  Power to Vcc (3.3v or 5v, depending on your board’s operating voltage).  Ground to Ground.  Data to a digital pin.  We usually use D7 in our example sketches because that’s the line on the Mayfly’s dedicated SDI12 Grove jack.  If you’re using a different board, you can select the pin, as long as it’s free and not used by anything else in your sketch or on-board circuitry.

The sketches you could use to communicate with the sensor can be found on our Github repo here:  https://github.com/EnviroDIY/Arduino-SDI-12

Note that Meter Group’s sensors always get shipped to you on SDI12 channel 0 (zero).  They MUST be changed to something other than 0 in order to make the sensor respond to SDI12 commands.  Otherwise, they are stuck in their default TTL serial mode, which isn’t great if you want to use more than one sensor on the same bus.  So use the example sketch named “b_address_change” to set the channel on your sensor.  Once you do this the first time, you won’t have to do it again, the sensor will remember this preference until you manually change it at a later date.

How you can use any of the other examples for the SDI12 library to query the sensor and display the data to Arduino IDE’s Serial Monitor.  If you want to integrate other hardware like a wifi board or other telemetry module, you’ll have to write your own sketches, since all our other examples are mainly written for the EnviroDIY Mayfly Data Logger board, which has a onboard microSD card socket, realtime clock, and xbee socket for compatible telemetry modules like wifi, cellular, LoRa, etc.

 

Attachments:

1. 

   teros12_wiring.png
   

[Shannon Hicks]

How many sensors are you wanting to connect to your Arduino board?  Do you have a Mega, or Nano, or both?  What sort of termination is on the end of your sensors?  Are you just wanting to display instantaneous sensor data on your computer or are you trying to build a logging device?

[Shannon Hicks]

Thanks for the update.  We’re looking into it, my guess is there’s a conflict between two libraries that is causing some issues, so we’ll have to dig into it and narrow it down.

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