Open Wave Height Logger revision C

The Open Wave Height Logger (OWHL) project has reached another minor milestone with the release of a new hardware revision, RevC.

This is a redesign of the three printed circuit boards, breaking physical compatibility with the older revisions, but it maintains software compatibility with the existing OWHL code (hardware designs and code available at the GitHub repository: https://github.com/millerlp/OWHL). The goal was to make the hardware a bit easier to assemble, and make certain parts (the micro SD card) easier to reach. All of the tiny surface mount components, save a few, are now on a single side of each … Continue Reading

Our new paper on limpets grazing microscopic algae

Lottia limpets sitting on an experimental plate in the intertidal zone.

Lottia limpets sitting on an experimental plate in the intertidal zone.

We recently had a new paper come out in Marine Ecology Progress Series, titled Quantifying the top-down effects of grazers on a rocky shore: selective grazing and the potential for competition (open access link at MEPS)  (permanent doi link).

This project involved putting a series of round aluminum plates out in the high intertidal zone at Hopkins Marine Station in Pacific Grove, CA, and allowing natural microalgae … Continue Reading

Things you see with a camera trap

I had the time lapse camera described in this post set out in the rocky intertidal zone in Monterey. Late one afternoon it caught these images of a ground squirrel venturing down into the mussel zone and picking small mussels (Mytilus californianus) off the rocks and eating them. If you replay the video a few times you’ll see a couple of the mussels on the edge of the bed disappear as the squirrel pulls them off and opens them to eat the insides.

Time lapse camera using ArduCAM

My time lapse camera board.

My time lapse camera board.

Design files and code for this project can be found here: https://github.com/millerlp/Time_lapse_arducam

The goal of this project was to build a cheap and power-efficient time lapse camera to monitor some of my experiments in the field. The camera would capture an JPEG image every 30 seconds and write it to a micro SD card, and be able to run off of AA batteries for a day or two at least. To accomplish this, I build an Arduino-like controller board that … Continue Reading

Arduino compile error: the filename, directory name, or volume label syntax is incorrect

GetFileAttributesEx D:\Arduino\libraries\SdFat/SdInfo.h
D:\Arduino\libraries\SdFat/SdSpi.h: The filename, directory name,
or volume label syntax is incorrect.
The error message above started cropping up shortly after I upgraded to Arduino 1.6.8 on Windows 7 x64. The cause seems to be due to some folder becoming locked in the Arduino compile pathway. One solution seems to be to close the Arduino software, restart it, and attempt to compile again. The program will compile ONCE, and then lock up and fail on a second compile attempt.

This Arduino forum thread recounts the same error: https://forum.arduino.cc/index.php?topic=366757.0

Another workaround seems to be switching the board … Continue Reading

Is live-tweeting meetings losing steam? #scicomm

As I write this in early 2016, sitting in the armpit of Silicon Valley (San Jose is, undeniably based on geography, the armpit of the south San Francisco Bay), we are beginning to witness the first signs of a contraction of the exuberant venture capital markets that have fueled utterly silly tech startup company valuations for the past few years. Twitter is one of the earlier startup darlings that has managed to decline in terms of share price as user base growth slows.

Now I’m beginning to wonder if we’re seeing a similar stagnation in adoption of Twitter as a … Continue Reading

Building a simple tide clock

Myself and Jeremy Long recently had a paper published in PeerJ (open access, free to read) describing the use of an Arduino microcontroller to predict tides and regulate the water levels in aquaria in synchrony with the natural tides. You can read more about that tide controller system here and further variations here.

As part of the process of putting a poster together on the Tide Height Controller project for a meeting of the Western Society of Naturalists, I whipped up a simple little 3-piece tide clock that shows a live display of the tide for … Continue Reading

Controlling tide height in lab aquaria

A few years back I posted about a set of Arduino libraries I wrote to allow an Arduino with an attached clock to predict the tides for a coastal site. In that post, I showed a variation on the theme that had a motor-driven rack that transited up and down in time with the tide.

Now Jeremy Long and I have published an open access paper in the journal PeerJ (external link) describing our use of that tide-predicting-motorized-rack, which we called the Tide Height Control system. We used the THC system to recreate real tide … Continue Reading

Using knitr and R to make instructor/student handout versions

I teach some of my lab sections using R, and so I need to create lab handouts that include nicely formatted R commands and R output as an example for the students. These handouts will also include exercises where the students will be writing their own R code, or interpreting the results, or generating figures. For these exercises, it is useful to also have an instructor version of the handout so that I can recall what I was hoping to have the students do, and so that other instructors in the course have some clue as to what I might … Continue Reading

Adventures in course management software: Canvas

Course management software is universally garbage, but Canvas has managed to be better than most. Which is a lot like saying “This is the best tasting pile of dog poop I’ve found today.”

The ability to create online quizzes that have the answers entered for easy grading should make for a useful system, but today I discovered that the precision of the system tops out at the 4th decimal place, which tends to be problematic if I want students to calculate fairly small probabilities (what is the probability of flipping a coin 10 times and getting 10 heads in a row?). … Continue Reading

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