NMEA into Router

[pat77]

The Raspberry Pi appears to be an excellent option for me, do you have a bit more information on this? I was excited to see kplex available for Raspian, and my Pi is looking to be put to good use. Anything special needed to be done to get the GPIO serial port connected to the NMEA device (no USB on my NMEA device). Or should a serial-USB converter be used? Seems like that would be a waste.

I did a generic google search for 'serial wifi nmea' which took me to this thread, and I happen to be looking to install this on my Westerly - a 1974 Centaur new to me last year.

What I'd like to connect to:
Misc: NASA Marine Instruments

Originally Posted by muttnik

I second JayH's thoughts.

If you don't want to buy a dedicated NMEA-0183 to ethernet box, if you run a nav computer connected to the airport, feed the usb from your multiplexer into that and run a program that will take the data from the serial line and put it out over the network. OpenCPN will do this for you. If you don't want a full featured chartplotter, Look at NavMonPC if your nav computer runs Windows or kplex if Linux. If OSX, kplex will run happily on it, but there's no OSX .dmg or GUI, so you'd need xcode and not be afraid of the command line or compiling from source to get it running.

An alternative would be something like a raspberry pi model B powered from a 12v to 5v converter (e.g. micro usb phone charger) usb from multiplexer in, run kplex, ethernet out connected to the airport. Sorted for ~$50.

Not industrially robust, but then neither is an airport or an i-thing.

[pat77]

The Raspberry Pi appears to be an excellent option for me, do you have a bit more information on this? I was excited to see kplex available for Raspian, and my Pi is looking to be put to good use. Anything special needed to be done to get the GPIO serial port connected to the NMEA device (no USB on my NMEA device). Or should a serial-USB converter be used? Seems like that would be a waste.

I did a generic google search for 'serial wifi nmea' which took me to this thread, and I happen to be looking to install this on my Westerly - a 1974 Centaur new to me last year.

What I'd like to connect to:
Misc: NASA Marine Instruments

[muttnik]

Originally Posted by pat77

Anything special needed to be done to get the GPIO serial port connected to the NMEA device (no USB on my NMEA device). Or should a serial-USB converter be used? Seems like that would be a waste.

You need to reduce down to the pi's 3.3v line level. The popular way to do that (which I copied) is to use a max3232 and 5x0.1μF capacitors (google "pi max3232" and you'll get a few hits). There appear to be good reasons to use a regulator to reduce down the 5v output rather than using the pi's 3.3v to provide power for the max3232 (e.g. here ). Am I right that those NASA instruments put out single ended NMEA 0183 v1.0 styley output? In which case you don't need to stress so much about this set up being a non-differential hack.

The pi serial port in raspbian is /dev/AMA0. By default there's a getty running on there. By using it for your instruments you'll loose it as a "console port" but what the heck. Edit out the getty entry for /dev/AMA0 in /etc/inittab and remove references to it from /boot/cmdline.txt. Don't have my pi with me but a little googling suggests the text to remove is:
console=ttyAMA0,115200 kgdboc=ttyAMA0,115200

kplex config is simple enough. feel free to PM me.

[Tymadman]

I have used a WiFly RN-171 from Roving Networks in my boat sending NMEA data to iRegatta on my iPad. I uses a MAX232 for level shifting and reversal. The WiFly only needs a 3.3V supply, a gnd connection and the serial data in so is very simple to hook up and get working.

[pat77]

Thanks - both replies very helpful. For doing a simple dedicated wifi network, the WiFly option seems excellent.

In my application, I'd rather have a wired interface to an existing lan, as I'd like to be able to connect to a wireless router and have both wan inernet access and access to the nmea data. The RPi will be a better fit for me in this application. I'm sure this will consume more power than the WiFly, but the other benefit is that I get an always on low power linux PC to use for 'free'. Details on the RPi implementation very much appreciated!

Thinking more about the WiFly, I was assuming you used it in ad-hoc? Or did you associate it with a wireless router and then connect your iPad to that? That solution would solve my problem of having internet access and nmea data....

Either way, I have not yet purchased the wind indicators yet, so not sure of their voltage levels, but assuming single ended. Great discussion, though, should be able to save some folks some $$ with these other options.

[Tymadman]

I've got the WiFly set up as an AP so multiple devices can connect. I don't have a separate router onboard.

[Tymadman]

BTW, there's a handy i-device app called iNMEAlogger which displays and records NMEA data received over WiFi for a user configurable time and then emails the log file (a text file).
I use this regularly when testing my NMEA to WiFi bridge - as recently as today in fact.
It's written by the same guy who does iRegatta. I also found a bug in the recent iRegatta update which causes the app to crash when receiving NMEA from WiFi. I contacted the developer who has since submitted an update with the fix which will be available soon.

[Deckhead]

Bit late to the party, but have you tried Digital Yachts iNAVhub, it can accept an internet feed and NMEA0183 and puts them both out wirelessly on the same hotspot. I am considering purchasing one, as I currently have to switch hotspots depending on what i am doing.

It works well with iNAVx, which is what i use for my navigating.