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Early Open Wave Height Logger battery tests

The Open Wave Height Logger prototype stack.

The Open Wave Height Logger prototype stack.

Following on the previous post about the Open Wave Height Logger project, I’ve been conducting a simple battery life test. One of the prototype OWHLs was powered by a 3 D-cell alkaline battery pack and shoved in the freezer for 32 days. The image below shows the collated daily data files for that time period, during which the data logger was sampling 4 times per second continuously. The black line is pressure in millibar, … Continue Reading

Arduino code for MS5803 pressure sensors

I have recently been developing a library for the Measurement Specialties MS5803 line of digital pressure sensors. These sensors are available in several different pressure ranges from 1 to 30 bar, they are submersible if installed in a proper housing, they communicate via I2C or SPI, and they cost around US$35. It’s fairly straightforward to interface the MS5803 with a microcontroller like the Arduino that can also communicate via the I2C or SPI protocols. They are a surface-mount style chip, meant to solder onto a 1.27mm pitch SOIC-8 layout (like the green board I used in the picture below). … Continue Reading

ATtiny84 LED display and heater project

Here’s a little project that uses an ATtiny84 microcontroller, programmed with the Arduino software, to build a thermostatically-controlled heater. It allows the user to choose a temperature setpoint, and then displays the current temperature using an Adafruit 4-digit 7-segment LED display over I2C. The youtube video below demonstrates part of the project, where an ATtiny84 processor is used to drive the Adafruit display.

To get the project rolling, I installed the ATtiny core files available from High-Low Tech. The instructions there helped get the ATtiny84 running on a breadboard. I use … Continue Reading

Using Arduino tide predictions

In the previous post, I outlined some Arduino code to generate tide height predictions for a NOAA tidal reference station.

Now let’s do something useful with this newfound functionality. In the experiments I run, it’s useful to keep intertidal animals like snails and limpets on a natural tidal cycle. In addition, some animals like high-shore limpets really dislike being continuously submerged, and will crawl up out of the tank and die when they dry out. In this case, I built a “limpet splasher” system that sprays water in the aquarium for a few seconds at a time with pauses in … Continue Reading

Tide height prediction with the Arduino

A collaborator of mine, Dr. Jeremy Long at SDSU, approached me with the idea of building a system to recreate rising and falling tide heights in his aquaria. One of the keys to making this work was having some way to specify what the tide height should be at any given time. While there is no shortage of websites and software that will give you tide predictions, they generally require an internet connection or a full-fledged computer to run tide prediction software, neither of which were necessarily desirable solutions when we wanted to control tides in aquaria that … Continue Reading

A thermocouple datalogger based on the Arduino platform

Updated with new Arduino code July 8 2012.

It never hurts to collect more data, and I often find myself wanting to record temperatures from a few extra animals. Most (all?) commercial thermocouple dataloggers that will record temperatures from multiple thermocouples cost several hundred or thousands of dollars. I set out to put together a relatively cheap 8-channel thermocouple datalogger based on the open-source Arduino development platform.

My 8-channel thermocouple datalogger. A single type-T thermocouple is plugged in to one of … Continue Reading

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