DIY Electronics?

Davidasailor26 · Jul 11, 2023

jviss said:
I know a couple of guys on the forum dabble in electronics, Arduino, etc., I just can't recall who!

That’s me!

I haven’t built my own network, but I’ve used a Yacht Devices YDNU-02 to connect a Raspberry Pi into the existing NMEA 2000 network. The adapter is probably about the cost of that buzzer, and Pi’s are still unobtanium, but if you can find a Pi for close to MSRP and get the adapter you have a lot more flexibility. You could get a conventional buzzer and have the Pi activate it from any out of bounds NMEA signal. Then you could add other sensors and I/O to the Pi for whatever else you want.

Davidasailor26 · Jul 11, 2023

Sticker price on a Pi 3 starts at $35, vs an Arduino Uno at about $25, so not wildly different. The hard part is finding a Pi for anywhere near $35. Supposedly later this year the supplies will open up more.

It looks like there are ways to use an Arduino with NMEA 2000 with Canbus, but they look much more DIY than the USB adapter that works with the Pi. I wanted the extra flexibility that the Pi would provide for things like SignalK and data logging so I didn’t dig into the Arduino options too much.

I do also use a Pi Pico microcontroller to get data from a SmartShunt and read voltages in my battery compartment, then send that wirelessly to the Pi across the boat. The Pico is only $4 and in many ways as capable as an Arduino. It looks like some NMEA 2000 / canbus libraries exist for it too so that might be worth considering if you don’t want to go the full single board computer route.

Davidasailor26 · Jul 11, 2023

jviss said:
You can get an Arduino for well under $10.

Replicas I presume? Yes, I suppose so. For that matter you could also get the Atmega 328p microprocessor itself that powers the Arduino for about $3. Add a couple resistors and capacitors and you essentially have your own Arduino to hook up to a Canbus adapter.

Davidasailor26 · Jul 12, 2023

jviss said:
What do you mean, replicas? As in not genuine? I'm talking about Chinese Arduinos off eBay. I figure they are all essentially the same. They use the same micros, anyway.

Technically an Arduino is a genuine product from the company that holds the Arduino trademark. The designs of their boards are all open source, so other companies are free to build their own boards with the Atmega 328p chip and the same form factor and pinout. Those should be marketed as Arduino clones, Arduino compatible, etc., and not actually Arduino. Not every Chinese manufacturer might be so precise as to be clear about that distinction. But they should functionally equivalent to a genuine Arduino, so it’s basically just an academic conversation. The clones might use lower spec voltage regulators or something, but the important part is the 328p that’s the same everywhere.

High Current · Jul 14, 2023

I’m actually an EE by trade, but my boat doesn’t have any fancy nav systems to tap into. I’ve been looking into building something with OpenCPN but good, weatherproof displays are also $$$.

Seeed studio made an Arduino CAN library using the MCP2515 so that part should be easy. NMEA 2k sounds a little more involved and access to the standard seems pretty restricted. The buzzer message would probably need to be reverse-engineered.

The profit margins on parts like this must be insane. But sidestepping them really has to be a labor of love for all the time & money you’ll put into making a one-off alternative. I also wonder what kind of volume RayMarine even sells and how much NRE they had to invest for ABYC & NMEA compliance etc.

Techstyle · Jul 14, 2023

I have mainly DIY electronics on my boat.
I have a Raspberry Pi4 running Openplotter, a 15.6" waterproof touchscreen at the helm, a 7" touchscreen at the Navstation. DIY GPS, AIS, Engine monitor based on ESP32 ($9 arduino), ESP32 based tank and Battery monitors. countless Temperature sensor. my old Seatalk 1 stuff - wind, Speed through water and depth are pulled into the Pi and available on the network, as is the VHF and everything is viewable on a laptop, tablet, phone, apple watch etc. Possibilities are pretty endless.

The Pi is connected to my stereo so on race days I can send my VHF sound through my stereo speakers, as well as use the Pi as a media system.

I built a NMEA2000 based battery monitor based on ESP32 for a friends boat that didn't have a PI and it works great and gives battery data for both his batteries on his Axiom MFD. The libraries for NMEA2000 are readily available and it is absolutely no problem creating something to either inject or extract NMEA2000 sentences to your network.

Take a look at the technical playlist on my Youtube channel, there are multiple DIY electronic projects: https://www.youtube.com/playlist?list=PLqHa5JFKHBLwxeCuc6uaa5TzAXVeqTyiD

Techstyle · Jul 14, 2023

jviss said:
Wow, very cool. I'm interested in your engine monitor. Have you open-sourced this?

of Course, the code is at:

GitHub - Techstyleuk/sensesp-engine_monitor

Contribute to Techstyleuk/sensesp-engine_monitor development by creating an account on GitHub.

github.com

there is a schematic and parts list. I have not been able to get the RPM working just yet, but I think I have a wiring issue. I haven't spent very much time trying to resolve it though.

the program assumes you have a Signal K server onboard, if you don't then you could adapt it to be NMEA2000 by looking at the example here:

GitHub - Techstyleuk/SensESP-NMEA2000-Battery-Monitor: This is the Battery Monitor for Nautical Sun.

This is the Battery Monitor for Nautical Sun. . Contribute to Techstyleuk/SensESP-NMEA2000-Battery-Monitor development by creating an account on GitHub.

github.com

or an easy but a little bit more expensive way would be to use a CX5003. We used one of these on a friends boat last year and it works great: Amazon.com
its a little less DIY and still much cheaper than the other brand versions - I bought it from Aliexpress for about $85

Techstyle · Jul 14, 2023

I think you could probably do an addressable buzzer for <$25. ESP32 ($9), CAN board ($10), Buzzer ($2), box. Most expensive thing would be the NMEA2000 cable!! (hint - relatively cheap on Aliexpress)

Techstyle · Jul 14, 2023

It comes with a brief manual and is pretty straight forward. The only real difficulty was getting the right dip switch setting for the ratio you need, and that . You do need to add sensors to the engine for coolant temp and oil pressure. many engines only have coolant switch and oil pressure switch to activate a buzzer. There are usually extra ports in the engine to add these but you need to understand the thread before you buy and make sure the sensor you buy has the right resistance - this was some of the negative feedback. I have the sensors I used listed below:

Temperature Sender
VDO 323-900 Temperature Sender Kit

Marine and Boad Senders | Tank and Fuel Gauge Sending Units | Defender

Shop Gauge Components & Senders for boats of all types at Defender. Get fast delivery and free shipping on eligible orders over $99.

www.defender.com

Pressure sender
VDO Pressure sender 0-10 Bar

VDO Pressure sender 0-10 Bar – R1/8 DIN 2999

VDO 360-081-029-062CPressure range: 0 to 10 BarThread: R 1/8 DIN 2999Sender resistance range: 10 - 184 OhmSensor signal: 1-pole common groundNo warning contact

vdo-webshop.nl

https://www.summitracing.com/parts/VDO-360081D

I bought the one we used from Aliexpress: https://www.aliexpress.us/item/3256802449243272.html currently $79.20

Davidasailor26 · Jul 14, 2023

I’ve got RPM’s working for my 3YM30 / Hitachi alternator. That alternator gives a square wave with frequency varying based on RPMs. I use an optical isolator to read those pulses into a Pico and count them per second there.

All of my code is at

GitHub - davidasailor/PiForBoat

Contribute to davidasailor/PiForBoat development by creating an account on GitHub.

github.com

JBP-PA · Jul 16, 2023

Techstyle said:
I think you could probably do an addressable buzzer for <$25. ESP32 ($9), CAN board ($10), Buzzer ($2), box. Most expensive thing would be the NMEA2000 cable!! (hint - relatively cheap on Aliexpress)

I suspect the most expensive part is the "NMEA 2000 Certified" logo