[Brandon Forsythe]

Hey Rick

Your method does work for the most part. However, when I moved the adafruit sd/rtc shield to another board I had to send the time to it again. Should the rtc maintain the time once set since it has its own battery? It does maintain the time without moving the shield to another board and cutting power for a minute or two but not sure yet what would happen if we lost power for 15, 20, etc minutes.

definitely better than what we had before though so thank you!

[Brandon Forsythe]

Rick

Thanks for the info. I believe this is working. I am having power issues now though too so I can’t be sure. The dc jack will not give consistent power. I may have fried something when we tried to set this up in the field using the gnd and vin pins (didn’t have the jacks at the time).

I may be asking more questions about the SDI12 setup then too. I have a CTD sensor we want to use in this manner as well.

Thanks again
Brandon

[Brandon Forsythe]

Thanks Rene and Rick

The battery is brand new but I did confirm it has the correct voltage.

Rick

How would I go about forcing the time set on the RTC now? I tried the code you provided as is and the time stamp is about 20 minutes off of actual time.

Thanks

[Brandon Forsythe]

Hi all

I am finally working on a system. I have an Arduino Mega 2560 – R3, the Adafruit Datalogging SD Shield, and just a DS18B20 temperature sensor (waterproof with 3 wires using a 4.7 ohm resistor). I can get the temp to record however I am having trouble getting the RTC on the shield to respond as it should. The shield seems to be working initially keeping track of time however once unplugged from USB and wait for 5 minutes the time doesn’t keep up. In other words when it is plugged back in the time resumes at the time the Arduino was unplugged. The shield does have a 3v battery backup which should maintain the clock when the Arduino isn’t powered.

I have attached the code as well.

Any ideas?

Attachments:

1. arduinotemplog.rtf

[Brandon Forsythe]

Hey neilh

Ultimately that is the direction I would like to take this. I first want to build a complete setup to have it up and running then have it broken up in ‘pieces’ for the students. I do want to have system though up and running that we can collect data and have students analyze sooner rather than later (ie…don’t want to wait for the students to build there own).

As far as what I want to teach, it will be based on water quality and in our neck of the woods in particular the Marcellus shale waterways. It will also show them as future scientists(we hope) that sensor arrays don’t have to be all that expensive (as SWRC puts it). I only recently learned of these systems while visiting the SWRC and thought it was awesome to be able to build these and want to do it myself along with others! But again, just not sure where to start especially on what is compatible to what boards and all.

B

[Brandon Forsythe]

Hi neilh

This project is a dual purpose in that primarily will be a kick-off learning tool but also be used by local high school students. It is an outdoor project with no power source other than battery and/or small solar panel and will also need some sort of water proof containment such as the pelican cases SWRC use. The application will be in a stream with ranges of conductance of 80 to 1500. Water level has been recorded at a height of ~3.5 meters in years past. All three parameters (level, cond, and water temp) are required to be of any good analysis of the system so they are all of equal importance. I am very familiar with SDI-12 sensors and protocols. I do believe the decagon ctd can also be used in 485 format as well. I do not need to stick with that particular device though but haven’t found anything in the same price range or cheaper that could provide relatively reliable data.

My biggest issue getting started with building my own Arduino sensor system is how to choose the appropriate board to start with? What do I look for when determining the interface and add-on capabilities on the boards?

[Author]

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