CTD Mark 1

Finally Mark 1 version of the CTD is finished - after lots of careful planning to keep the PCBs on the datalogger shield, I needed to add a voltage divider so ended up with adding another board, so it looks like a dog's breakfast.

First deployment using an axe as a weight and a paddleboard to get onto the lake

Underside of CTD showing arduino and ports

Top of CTD with extra board and also the pressure sensor is visible 

First data from CTD

After much coding and making, here are the first data from the CTD

Open source chromatography software

Open source software (opencheom.net) can read a multitude of file formats including GC-MS data.  Can also read CSV files so could easily be connected to an arduino running processing or a firmata shield

Conductivity and arduino

Building a small submersible conductivity probe using the details from EMEsystems.  I used to use a BASIC stamp for some of these measurements so time to pass this info to the Arduino.

Thermistor array for under ice

Building a thermistor array to leave under the ice for the winter to look at cold stratification of the lake over the winter. Using an adafruit datalogger and 10K thermistors from adadfruit, I have a short string of three thermistors which will be placed in the lake next week hopefully.
String is complete for testing - here are the values being logged to the SD card for 3 thermistors at three depths (currently sitting in the workshop so values are in the 20s).

Adafruit datalogger shield

Adding an SD card to the datalogger would be a good step. Here is the adafruit loggeshield with a temp and light sensor attached. Using ladyada's sketch called sensorSketch under folder dataloggerShield, you can see the values in the DEBUG window.

Then using adafruit-light-temp-logger/lighttemplogeer.pde, the data is logged to the SD card and also a time stamp added. Works like a charm.

NOTE: to have the LEDs working, you need to add a jumper from DigPin2 and 3 to the LED connections on the shield (yellow and orange jumper on photo)

Now to take the sensor circuit and enclose it in an outside case and connect to an XBee and we have a wireless station.

SDI-12 to arduino

Control panel for DO datalogger
Originally uploaded by whirlymark

Interfacing SDI-12 to arduino means converting SDI-12 to arduino or serial 232 input. Using a converter like the WaterLog H-4191 would work and LABView have some ideas on SD-12 usage. If the arduino used a MAX 232 chip or Sparkfun version to convert to 232 or the MaxSerial arduino from Freeduino

Better to use the %V and convert to TTL but SDI-12 is one wire for TX and RX. Ideas at AVR forum, with their final thoughts being

So I guess your best option is 3 LL parts, 2 inverters and one buffer with an output enable.

Ok here is my final solution for you, this combo should work.

Dual inverter for TX/RX: SN74LVC2GU04 running at 3.3V (5V tolerant inputs) which can be converted to DIP using SOT23 to DIP Adapter sku: BOB-00717 from Sparkfun

Tristate Buffer for Tx: SN74AHCT1G126 running at 5V (Vih min is 2V, so 3V3 logic should drive it fine) which can be converted to DIP using SOT23 to DIP Adapter sku: BOB-00717 from Sparkfun

That dual is nice, also. Running at 3.3V, the Tx inverter outputs 0/3.3V which is acceptable by the tristate buffer so its function is inversion, only. On the Rx side, the input is 5V tolerant, so it behaves well receiving on the SDI-12 bus. It is also $0.40 in quantity of 1 and $0.11 @ 3K from DigiKey. So, it won't break the bank.

Alternative solution: Now my solution was to use the ADG3304 bi-directional voltage level shifting IC to also provide 5V logic level enables for the tri-state buffer, as well as logic shifting for the RX/TX

Water flow sensor

A cheap hall effect water flow sensor from Seeed Studio only $10 - wow!

Monitor temperatures remotely

Read a thermometer on-line using an arduino and an ethernet board, and also Tom Igoe used an ethernet shield to upload data to Pachube, and also in the arduino library
Sparkfun has a great enclosure for an ethernet shield on an arduino and there is an interesting site about using a smart Phone to control it all.

Easy SMS messaging from arduino

from Make Club

Cheap and easy SMS via GSM for your MCU

http://hackaday.com/2010/10/18/cheap-and-easy-sms-via-gsm-for-your-mcu/

Non acronym version of the title: send and receive text messages via cell phone communication towers using an Arduino or other microcontroller. “We’ve been doing that for years!” you cry, well yes, technically. But [Fincham] lays it outs simply; commercial offerings are expensive and finding a cell phone that uses RS232 now a days is getting difficult, so a new way of doing the same old is necessary. The good news is USB GSM modems are readily available, cheap, and only require a few interface pins to get them talking with an Arduino. In fact, the image above is all you need.

USB Stick Storage

After reading the excellent "Practical Arduino" book, there is a lot of talk about storing data on a removable USB Stick using a VDIP1 chip from Saelig. Good explanation and blog on interfacing chip to arduino.