Weekly Update 4-24-17 to 5-01-17

This is the last blog post for the semester. I will start by talking a little about the work I did over the last week, and then talk a little about the semester as a whole.

This week I tried to assemble three more Sharkduino V2.2s, and ran hardware tests on all the existing Sharkduinos. The Sharkduino assembly was a failure. I was careless and rushing so I messed up the batch. This is the down side of batch assembly, if I have a bad day I don’t just mess up one Sharkduino. This pushes us outside what I feel is an acceptable failure rate for assembly so I am thinking about how to prevent this from happening in the future. First I think that I will only assemble two at a time, doing three is too much for one session. I will also make sure I dedicate the needed time to assembling them, and not feel rushed by deadlines and other commitments. Finally I will review my assembly procedure checklist to see if I can make any improvements to the process. Also this batch may not be a total loss, some of the Sharkduinos may be repairable. I tried to repair one and broke it further, but I am going to try to repair some of the other ones before the summer.

The next thing I did this week was test all the existing Sharking with the help of the rest of the team. We did this to make sure we would not accidentally put defective hardware on an animal over the summer. Through our tests we found that all the devices were fully operational except for one V2.0 that had a broken RTC battery backup, and one V2.2 that had a defective gyroscope.

The problem with the V2.0 was that the power in pin on the IC from the battery backup was shorted to a unconnected pin. A picture of this from the microscope can be seen below. This is interesting because this is the same error that I tried to fix on one of the V2.2s, and led to me fully breaking the V2.2. When I went to repair this V2.0 I was able to use what I had learned from the failed V2.2 repair attempt and fixed this one successfully.

RTC solder bridge. (sorry for the bad picture quality)

RTC solder bridge. (sorry for the bad picture quality)

Repairing the V2.0 was a reassuring way to end the semester after the failed V2.2 batch. While that failed batch is a minor setback it does not detract to much from this being a pretty good semester for Sharkduino. We were able to create two new iterations of the hardware, V2.1 and V2.2, that make the system more power efficient. We developed an easy and cheap waterproofing technique for tank deployments. We were able to better diagnose a lot of the issues we have been having with the tag. We repaired some of these, while others, like the LiPo charger, we have a good roadmap for fixing going forward. Finally we were able to build a lot of new Sharking. This both taught us a lot about PCB assembly, will allow us to get a lot of good data over the semester.

We have a lot of exciting plans for next semester. I will make sure to keep updating this blog with them as we do them. I may also post an update or two over the summer if I get anything for the project done. I have an internship this summer but the project will be continued by two other researchers who will be at William and Mary working on Sharkduino.