Ok… I’m sorry this is another SUPER technical post. I promise the next one won’t be technical and will have pretty pictures. To say sorry to you non-technical people I will tell you a joke. Here goes!
“No matter how much you push the envelope…..
It’ll still be stationery.”
Ahhh I can hear you growning… OK OK How about this one!
“Whenever my wife starts singing around the boat I immediately go on deck…..
That way the neighbors know I’m not hitting her”
Alright, that last one I’m going to pay for and I still don’t hear you laughing. You want funny jokes, go to Youtube and lookup “Jimmy Carr” (careful, NSFW).
Now back to the technical stuff. When we initially refitted Party of Five in Key West we opted for some kickass electronics that really made her a modern marvel. One particular item that we added was an AIS device from Vesper Marine that not only offered cutting edge AIS features, but as an added bonus it connected to our WIFI network to share ALL our instrument data. Seriously think about that. I could be lying in my bunk and see our SOG, COG, Wind Angle, Depth, hell even our Rudder Angle on any tablet, phone or computer that I chose. This was a fantastic feature when we were doing overnight passages on shifts. I could wake up, flip on a tablet, digest the data, feel better and go back to sleep! Very cool!
Unfortunately when lightening took all our equipment that device was one that literally exploded inside. Although I yearned to replace it, our budget just couldn’t swing the price difference between it and the basic device ($1199 vs $599). I sighed and ordered the basic device resigned to the fact that I would loose this wonderful feature (still bought another Vesper device, however this was the only device I didn’t replace same for same).
We have now been without that feature for a year and half and I still miss it badly. Most days I just put it out of my mind, but lately I have been thinking about it more and more. The other day was the last straw. I was helping our friend Jamie on Liberty Blue fix his Garmin WIFI device which had not been working since he bought the boat. Once it was fixed, I then had to listen to him gush about how awesome it was once he started playing with it. Dammit, I wanted that feature back.
So the next day.. I sat and pondered… In the year and a half options had changed and prices had come down, but I was limited by our location. Our chartplotter manufacturer had a stand alone device that offered that functionality for $199USD. Unfortunately $199USD in the USA means $300-$350 USD down here in the islands, still out of our price range. Even at $199 I thought it was overpriced as the device is very simple (basically a serial to WIFI bridge). Now deflated, I began thinking “outside the box”. The device was very simple, and I started thinking about designing something to provide that functionality. Of course I quickly realized the error of my ways and instead fired up Chrome. The world is a big place and someone must have already done the hard work for me. I unleashed my Googlefoo and within minutes came across 3 open source projects doing exactly what I required. I spent an hour studying each one before picking the one I though was the most mature and also had the smallest bill of materials. My original plan was to order all the parts and then have some upcoming visitors bring the items. However, I quickly realized that I probably had everything aboard Party of Five. Yes its crazy that I would have all the parts to build a NMEA0183 to WIFI bridge aboard my boat. Sigh… I actually had enough parts aboard to build 3 (I just couldn’t give up my electronics hobby when we left land).
Anyway…. Here is the design I ultimately choose. The hardware and software were designed by a fella called Larry Littlefield and you can find the entire details at this link.
A quick look at the design and you can see its designed around an ESP8266 WIFI module, and very simple. When that $8 device appeared on Ebay it shook up an entire industry as previously that functionality cost at least $100. These days, I’m pretty sure those modules can be bought for $3 USD. However, the true genius of this design is the 2N2222 level shift transistor circuit. That end of the circuit converts the unusable high voltage signals from onboard equipment down to voltages the ESP8266 can handle (plus it inverts it). In true “smart designer” style, Larry freely admits he borrowed the design from other circuits online (why work hard, when you can work smart). Finally, the best part of this design is that its modular. Larry has included lots of “Fancy Shit” that trashy people like me don’t need. R8, D1, S2, S3, R9 and LED1 can all be safely omitted without affecting any functionality I will use (I don’t need no fancy LED to tell me its in config mode). I also chose to loose the LD1117VXX circuit as I has a metric shitton of Ebay power supplies aboard that could provide all that functionality (ironically using that exact chip).
Alright, so we now had a design and the parts on hand. It was time to make some smoke and burn my fingertips. I got all the parts out, heated up the soldering iron….. Then sat there staring at everything as I realized I didn’t have a proto board (a fiberglass board with holes for building one-off circuits). I would need to build the circuit “Dead Bug” style, but it had been years since I had done anything like that. To make matters worse, boats move, shimmy and shake. Anything I built would have to be robust enough to last. More pondering and two coffees later I settled on a physical design and begin piecing stuff together.
First I needed to build a harness to actually program the EPS8266 with the code. I thought it only had to work once so I was pretty sloppy with my soldering (that bit me later).
After successfully flashing the board, I moved onto building the actual circuit that would attach to the board and provide all the other functionality. Here you can see the start of the circuit and the power board beginning to get wired up. I was still considering using an LED at this point. We will talk about those resistors you see later in the article (super nerds will note the colors).
The basic physical design. Just a few more solder joints. What probably doesn’t come across in these photos is how small this stuff is. The square chip on that board is smaller than you pinky finger nail!
I also had some pretty nice “project boxes” buried in one of POF varies holes. Here is the finished circuit mostlyl soldered up. The yellow wires sticking up will connect to a switch on the top of the box to provide the “Config” functionality. It was shortly after this point I decided to test everything (moron, I should have done it long before this). Unfortunately, I had a distinct failure to “chooch”. No matter what I did I just couldn’t get the module to go into “Config” mode despite the fact that I reprogrammed it 20 times and never got and error (remember the shitty harness I built)…
Much head scratching and swearing ensued. After, literally 4 hours of troubleshooting I discovered that the resistors were not labeled correctly. I thought I was using 4.7 K-ohm resistors when in fact they were actually 4.7 OHM resistors.. SONOFABITCH… someone at Amazon owes me 4 hours of time!
So after 4 hours of frustration, head banging and face melting swears, I finally got things straightened out. The module booted up and quickly advertised the “NMEA Bridge” WIFI network. Cheers went up all around (Ok, I was the only one that cheered, but I cheered loudly enough for 5 people, the other crew just stared at my angrily). Once I had verified it was working correctly I moved onto the next part of the build. I poured epoxy over everything except the wireless chip (wireless stuff does funny things when encapsulated in resin, pretty sure it has something to do with capacitance). Once the epoxy kicked, I wired the unit up and properly mounted it. Here it is, in its permanent home.
I know some of you won’t be satisfied until I show the result. Well here is OpenCPN running on my laptop showing the streaming data (yes, even AIS). Every piece of NMEA0183 data is available for OpenCPN to display. On a side note, the charts I’m using with OpenCPN are pretty far out as the depth reading on our gauges is 19ft from my keel, however the charts say I’m in 10ft of water (from the surface).
Conclusion…… For about $10 USD I was able to replicate the functionality of much more expensive devices. In the end it took me about 8 hours to build and test the device. Rhonda and I had multiple “domestics” during the day. My kids learned a whole bunch of new swears. I burned our salon table, twice…….. Hell, if that is not a cruisers success, then I don’t know what is!