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Old 21-01-2014, 11:19   #61
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Join Date: Jan 2013
Location: Bellingham, WA
Boat: Ranger 29 sloop
Posts: 2
Re: DIY Research and Development

Yes, It would be great to follow these projects, tell us where to look. We will follow your rants and raves. I'm enjoying my boat monitor but at the same time I'm leaning towards removing all unnecessary items from my boat and sailing a simpler way... can't really decide if I'm geeky or trad I guess...
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Old 31-05-2014, 22:34   #62
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Location: currently tenessee
Boat: cabo rico 38
Posts: 50
Re: DIY Research and Development

I haven't checked this thread in awhile as I have been busy actually
building and testing some of the things I mentioned here.
I hope this gets to some of the folks needing it.

I have seen lots of mentions on other threads about the cost of NMEA183
multiplexers (around $200).

I have board layout, schematic, and firmware to construct
a 4 to 1 NMEA multiplexer. I built the unit on Radio Shack perfboard
with point to point soldering in an evening. I have used the unit for 3 years without issue. Total part cost was $15.

The unit does buffering (the only way to do 4x4800 baud in and 1x4800 baud out). It also uses a "high watermark" so when it falls behind due to too much
traffic it starts filtering out "unimportant" messages like GPS satellite signal quality sentences which are transmitted every second even though the data is not time critical. The units can also be "cascaded" so one
may use two units to get a 7 to 1 multiplexer or three to get a 10 to 1 etc.
The output baud rate can also be configured up to 119.2Kbaud if the output is to a PC rather than another NMEA device (reduces the buffer time and relieves congestion).

In pictures:

---------- --->NMEA in of another MUX
NMEA183#1 ---->| | |
NMEA183#2 ---->| NMEA |_____|-->PC Serial Port or USB adapter
NMEA183#3 ---->| MUX | |
NMEA183#4 ---->| | -->NMEA dev (AIS,DSC,Autopilot etc.)
If anyone is interested in building one of these I own all the design info and software so there is no problem with copyright/licensing.

This is not in kit form, it is a schematic, a layout suitable for point to point soldering, parts list, and firmware file for a PIC18 processor. I can program a few PICs if anyone is interested and doesn't have
a programmer (PIC programmers go for about $50). All the parts
are available from (cheap) or your local Radio Shack ($$$).

If there is a lot of interest, I can get some boards printed and put them
with a parts kit and pre-programmed PIC. Cost would depend on volume
but should be $50-$75. (as opposed to $15 to point to point a beta).

Email me at this forum if you are really interested. Let me know if you
feel comfortable acquiring your own parts and point to pointing a beta test version or would only be interested in a PC board and parts kit which you could stuff and solder. Point to Point is now, PC board is only if I get
enough interest or help to fool with it.

I don't mean to sound
stand offish but I am busy with other projects and don't want to do a lot
of work for things that folks are curious about but never actually build.

Any help would be appreciated. Its seems the technical expertise available on this forum is increasing exponentially.

And my physical design prowess is zero. I bully electrons and throw
code but mounting things in nice boxes with bezels is not my forte.
I mounted mine in an old aluminum box off something i cannibalized.
(I have been known to use spam cans in a pinch). The holes for the LED's were cut with a pair of wire cutters. So if we do pc boards
and someone wants to do a pretty box then I'd love it.

On other fronts, I do have my realtime browser-web server-message bus-hardware interface infrastructure now working and running my off-grid home tasks. (yes i am doing near realtime browser code, no polling and no apps required) I am
finally ready to start on the open source NMEA2000/CANBUS stack I talked
about ages ago so I can duplicate this infrastructure on my boat.
Remember the idea is to buy transducers from Garmin/Raymarine etc and
use tablets/phones/pc's as the interface units talking to a server on the NMEA 2000 bus and supporting a local wifi.
I met my cost targets so far as the entire setup running my off grid house cost approx $75. The CANBUS/NMEA stack will sit on the existing hardware which is already CAN enabled so my target of an instrument server open source for under $100 should be easily achievable if you don't
include my time. Hope to have it all running before my next run to the islands.


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Old 31-05-2014, 22:48   #63
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Posts: 50
Re: DIY Research and Development

Sorry for the misprint.
Its a 3 to 1 MUX. Not a 4 to 1.
I forgot i ran out of interrupts on the processor
and had to scale back to 3 to 1.
Everything else is still accurate and you can still
cascade them to get 3 to 1, or 5 to 1, or 7 to 1 etc
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Old 07-06-2014, 18:47   #64
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Join Date: Jan 2013
Location: Careel Bay, NSW Australia
Boat: Sparkman & Stephens Deb 33 - Design 1873 MkII deep keel - 1974 UK/Dutch built version Tartan 34C
Posts: 100
Re: DIY Research and Development

Ahoy fellow tinkerers,

I'm quite interested in some of the conversation here, as I recently got myself an Arduino starter a kit, with various shields, etc for Ethernet, temp/humidity, LED display, light switches. Main thing that piques my interest is learning more to enable at-sea repairs and to create some needed gadgets for onboard. I also run a startup business that develops software for cloud and am particularly interested in combining interconnected 12V electronics (IoT) in niche areas like sailing or other transport.

As a kid I dabbled with the soldering iron, kits and prototype boards, but alas many years later my skills need sharpening, so I probably unable to contribute much on the projects discussed here (at least until I've improved somewhat). Generally interconnection with WiFi, GPRS (3G, 4G), NMEA2000, Ethernet and systems are where I could help. I've worked in IT & Telecommunications for over 22 years in these areas (not NMEA2000, just picking this up but is simply a telemetry type protocol implementation).

I look forward to building some projects and sharing these with you, hopefully getting to a point where I can make some more complex designs that some of you have created. Right now I'm building from starter book projects, then I'm building an iRobot Roomba Arduino hack to learn about programming servo motor control. I'm then going to focus on 12V supplied Arduino controlled servo motors, with GPRS and sensors, which can be used for boat environmental monitoring, alerting and actioning... opening vents, scaring birds, sending data, etc.

Also an onboard butler robot that can fix & serve drinks, whilst cleaning the floor would be awesome! : )

Sent from my Nexus 7 using Cruisers Sailing Forum mobile app
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arc, research

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