The Story of a Lost and Found Sensor

When two unidentified sensor packages wash up on the Florida coast, the hunt is on to find out what they are, and who they belong to.

Last week the folks at the MD Buoy Project posted to Twitter that some friends of theirs had found something interesting on the beach in Marathon, FL, and the hunt was on to find out both, who it belonged to, and what it did.

Housed in a bottle blank, the preform that plastic soda or "pop" bottles are made from, the main board of the sensor package is a clone of the Arduino Nano, built around Microchip ATmega328P chip.

Beneath the Arduino clone however was the real clue, a 60×20 mm purple board with a thermistor mounted on it to measure sea temperature logging to a Microchip 24LC256 2-wire serial EEPROM. The clue of course being that the custom board was purple, which leads us directly back to one fabrication house in particular, OSH Park.

The next day the plot thickened when a second identical sensor package was found washed up on Palm Beach, FL, over 150 miles from the original.

Things were starting to get interesting. I reached out to James Neal, the owner of OSH Park, who volunteered to sift through their catalogue and see if he could identify the original owner.

It turned out it didn’t take him that long to find them. Narrowing things down by size still left him with 1,200 possible boards. However, fortunately for him, searching through all of them wasn’t necessary as Neal got lucky, and found an earlier revision of the same board within the first dozen or so he inspected.

However he wasn’t the only to recognise the board.

Designed and built at the NOAA’s Atlantic Oceanographic & Meteorological Laboratory for the ReefCheck Project, the two sensors found on the Florida coast were deployed as part by the Coral Restoration Foundation off the Keys in collaboration with the NOAA and the University of Miami’s Rosenstiel School of Marine & Atmospheric Science to monitor coral outplanting.

So at least, and unlike some of the other hardware hunts we’ve been on in the past that were a bit more dubious, I guess that all’s well that ends well. But if you’re walking along a beach in Florida any time soon, and find another, here’s the documentation on how to read the data from it. I’m sure the NOAA would be interested in having the data, if not the sensor itself, back.

Alasdair Allan
Scientist, author, hacker, maker, and journalist. Building, breaking, and writing. For hire. You can reach me at 📫
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