This has been a very eventful week. It started was a mad rush in Williamsburg to complete the layered Sharkduinos, know as Sharduino V1. I had to assemble as many working layer 1 and 2 boards as possible as quickly as possible, and then assemble them with arduinos. The goal was to be back at the eastern shore Wednesday, with a hard deadline of Thursday morning. The deadline was because a suprise I will tell you all about later.
Assembling the boards was harder than I anticipated. They just have a lot of stuff on them and one slightly misaligned chip can make the whole board unusable. In order to move faster I also did almost no trouble shooting on boards when they did not work. I just threw them into a pile and started work on a new one. I did this because it could easily take a full day to track down a problem on a board, just to discover it is a problem I can not fix. I did not want to fall down that rabbit hole with such a tight deadline so I will examine the boards for the exact cause of failure when the semester starts up.
Eventually I got two mostly working Sharkduinos built and loaded up the car to head back to the ESL. The mostly in “mostly working” comes from the LiPo charging circuitry. I could not get it working on anything so I just gave up and decided I would use an external charger and just plug in batteries to the sharkduino.
In addition to the Sharkduinos I also completed a layer three board. The layer three boards are small boards meant to be wired up physically separately from the main device and exposed to the water in order to take pressure and temperature readings.
Layer 3, top side. The passive components are shown here, the sensors are on the reverse side.
When I got to the eastern shore on Wednesday the researchers there handed me prototype three still sealed up in the heat shrink tubing. They took it off on Tuesday, which means it spent four days attached to a shark. When I opened it how ever I only saw 90 seconds of data. I then tested the battery and saw it still had most of a charge. What I believe happened is that when we used the iron to seal the heatshrink the battery got to how and turned off. It needs to be unplugged and plugged in to reset so once it turned off it did not turn back on until we retrieved the tag from the animal. This was not a totally useless run however, we learned about how the heatshrink old up during longer deployments and we learned that we need to be more careful with the battery in the future.
Then next day we sealed up the two Sharkduinos for deployment on animals. Unfortunately we were only able to attach to one animal, but we left the other Sharkduino running out of water. THe next day one of the researchers went paddle boarding and we attached the device to the bow of his board in order to get data from a tag in open water. When he returned we opened the device and found it still powered on, but when we looked at the data we found it had stopped recording the night before. We believe that the uSD card had come loose and this stopped the data recording. Later that day we detached tag A form the animal and examined the data. We found a similar result, the tag stopped recording after only a few hours. Since the tags are identical we believe that the same uSD problem effected this tag as well.
A sharkduino V1 with its heat-shrink tubing
The uSD slot and attachment on the Sharkduinos is clearly flawed and will be changed in future versions. For these version we glued a small piece of plastic onto the front of tag B in order to hold the uSD card into place. We then sealed the tag and attached it another animal. This was on Friday and we have not retrieved the tag at time of writing.
In addition to tag deployments I have been helping the researches at the ESL with whatever they want me to do. Also I have written documentation and assembly instruction for the Sharkduino. Finally I have been doing other administrative work in order to insure I have good record of the work done this summer on the project.