Raspberry Pi as Onboard Computer

[Dsanduril]

Originally Posted by abarrow

I would add to look seriously at using a USB connected SSD instead of the SD card. They are much more reliable, and run faster. I've been using OpenPlotter for the past two years and I'm very happy with it.

I use an attached SSD on some of my Pi projects, but for this one I really like having the box without any dangling connections. Power, and HDMI when I want to use a monitor. With data over WiFi and VNC really all I need is the power cable. Means I can tuck it out of the way and not have to worry about cords, etc.

I was a bit suspicious of using the SD card for storage of everything but so far (knock on wood) I haven't had any issues. Keep a spare one completely ready to go, and backup navobjs and a couple of other files over the network.

[S/V Adeline]

Most of the returns are in agreement that a 2gb card would need to be rewritten to the level of 10tb of data before such damage occurs. Considering the low cost of 32gb cards one could have several backup drives lasting past their children's lifespan for about $100, and same research states that flash drives are a wear item as well. I believe this is worrying over essentially a non issue.

[conachair]

Originally Posted by benet250

also openplotter will not run on RPi4, the RPi3B is the one to get,

Openplotter installs fine on a Pi4 now >
OpenPlotter 2 roadmap

[Axel Rappe]

Lots of good comments and info. I'm thinking to do the same.

In addition to the nav part, I intend to run a pi as a boat automation system. Using open hab. Mostly for smart lighting, allowing for less cabling, but also for automation of onboard systems like water maker flushing and system monitoring. Bilge are humidity monitoring and so on..

More to come on the topic while setting up the system.

As a side note, on storage. It seems that having a small SD card is preferable, installing a USB or ssd drive to handle data to avoid problems with rewriting data on the SD card. I am by no means an expert on how PIs handle data, but I suggest googling it to get a better understanding.

/ Axel

[steffan]

Originally Posted by Axel Rappe

In addition to the nav part, I intend to run a pi as a boat automation system. Using open hab. Mostly for smart lighting, allowing for less cabling, but also for automation of onboard systems like water maker flushing and system monitoring. Bilge are humidity monitoring and so on..

More to come on the topic while setting up the system.

I have similar goals for lighting and monitoring. I look forward to seeing your progress. I found this interesting and hope to replicate: Signal K DIY sensors with Signal K

Originally Posted by Axel Rappe

As a side note, on storage. It seems that having a small SD card is preferable, installing a USB or ssd drive to handle data to avoid problems with rewriting data on the SD card. I am by no means an expert on how PIs handle data, but I suggest googling it to get a better understanding.

/ Axel

Assuming the leveling algorithm on the SSD is the same as the SD card and the capacity and reliability are the same how is the SSD better? You should have a fresh backup image of the SD card anyway for the OS and software, now you're going keep a backup image of the SSD as well? A 32GB Samsung EVO+ is under $9.

[Dsanduril]

At the commercial/household level SD and SSD are both NAND flash memory and they both suffer from wear. Again at the commercial/household level each bit of NAND can generally be written ~1000-3000 times. There are NAND technologies out there (pSLC, SLC, etc.) and other non-volatile memory products that have significantly higher write cycle life, but are also so much more expensive that they don't show up too often in everyday use (a 32GB pSLC SD card runs $50-$100 while the same in typical MLC form from a quality brand is < $10, from a cheap brand it may be significantly less than that).

The life of both an SD card and SSD can be extended by two common techniques:

1. Wear Leveling - a controller on the drive/card evens out the wear so that every bit sees the same amount of usage.
2. Over-provisioning - you get a 32GB device but format it to only use 25GB and reserve the remainder as replacement/spare space to be used when one part starts to wear out.

For the everyday user you don't see these things, but there really is very little difference between an SD and SSD. The key is in the wear-leveling algorithms in both devices (and yes, there can be a wear-leveling controller inside that tiny microSD card). If the OpenCPN logfile is allowed to write to the exact same memory block every time it writes (or the config file, or whatever) then it is not hard to wear out that block and to corrupt the file system doing so. Cheap NAND devices may have bad wear-leveling algorithms (or none at all), quality ones have better wear leveling. Getting that level of detail out of manufacturer specs is a challenge and so you end up having to go with recommendations from the web unless you want to pony up more $ for the SD card (or SSD drive) than you did for the Pi itself - then you can find genuine specifications on wear-leveling, provisioning, and all the other fun details.

[conachair]

Originally Posted by Axel Rappe

Lots of good comments and info. I'm thinking to do the same.

In addition to the nav part, I intend to run a pi as a boat automation system. Using open hab. Mostly for smart lighting, allowing for less cabling, but also for automation of onboard systems like water maker flushing and system monitoring. Bilge are humidity monitoring and so on.. .

/ Axel

For monitoring ESP32's are very much worth a look, send the data over wifi. And jlcpcb to make the boards with sensors already soldered on, just add headers and plug in an ESP32. Hopefully......
These turning up any day now >

https://easyeda.com/editor#id=|9b753...5190814850862c

[Eight Sails]

Good post. Thanks....


I installed OpenCPN and SignalK on a Pi 2B a number of years ago, back when that was the latest and greatest setup and OpenPlotter wasn't yet available to make things easier. I'm still using the Pi 2B hardware but did a clean install of the OpenPlotter package on a fresh SD card when upgrading. No more hand editing Linux scripts and configuration files--much better now!



Like others who have already posted, I get AIS and GPS from a GPX2200 VHF. I get NMEA183 data for the other usual things like speed, depth and wind from the old instruments that came with the boat. Everything gets multiplexed and delivered to an assortment of phones and tablets with WiFi, in addition to being directly available to OpenCPN running on the Pi.



Here are a few more thoughts, based on experience:


If you use raster (BSB) charts, you may not need a Pi with as much processing power as if you use vector (ENC) charts. At least, I haven't needed to upgrade my Pi 2B and I'm running OpenPlotter successfully on it. In Canada, government (CHS) raster charts intended for recreational boating are inexpensive, whereas vector charts intended for commercial use are ferociously expensive, to the point that if you want vector charts for a reasonably wide area, a commercial chart plotter and map card will end up being cheaper. I happen to like those old-fashioned raster charts, so it works OK for me. Your mileage may vary....



Other bits matter even more than the SD card. I've found that the serial-to-USB converters needed to integrate AIS/GPS and instrument data from external sources are the weakest links in the system. A collection of good enough ones to use on a boat cost me more than the Pi. I've used different converters, ranging from super-cheap RS-232 converter chips you can buy by the dozen on Amazon to much better RS-422 converters I bought from Sean D'Epagnier's OpenPlotter store a couple of years ago. This is not something to cheap out on: when the converter fails, you lose GPS, AIS, whatever.... The cheapest ones not only can fail; they will fail. Its a question of when not if.



Inadequate power to supply USB devices (and board-mounted hats) is also an insidious gotcha. If you have a recent Pi with enough USB ports to plug in all your external devices, you need to make sure it has an adequate power supply. If you add an external USB hub to increase the number of inputs to your Pi, that also needs to be powered and the quality of the hub becomes a factor in your system (not all powered hubs are created equal). If OpenPlotter stops receiving GPS and AIS data from your VHF radio, for example, it could be because the serial converter failed (see above), or it could just be that the converter isn't getting enough power from the USB port. Problems like this can be frustrating and time-consuming to diagnose.



Even below decks, I've found wetting to be a problem for consumer-grade monitors. I was able to locate the Pi and related bits (USB hub, serial converters, etc.) in a spot where the boat would have to flood before they would get wet. The monitor was another matter. The 12V and USB powered monitors you can buy for under $200 on Amazon work fine until just a little bit of water gets in. Unfortunately, a marine-grade, waterproof touch monitor with a high enough brightness rating to use as a cockpit display costs much, much more--as much as a commercial chart plotter.



You may not think you need a marine-grade display because your boat is dry enough to use a consumer-grade display down below and you can use a smartphone or tablet in the cockpit. That used to be my thinking too, but when the old chartplotter mounted to my steering pedestal died last year, right before the Lake Ontario 300, I really missed having it, even with OpenPlotter, WiFi and several tablets at my disposal. IMO smart phones and tablets aren't a 100% adequate substitute for a bright, waterproof cockpit display with a hard-wired power supply.



Below decks, as a primary display for the Pi, I tried using a low voltage, USB powered monitor but ended up using a WiFi tablet instead, with VNC installed on it. That let me configure OpenPlotter to run "headless" without an attached, wired monitor and keyboard. There's a hatch over my nav desk. A leaking hatch seal allowed a tiny bit of water to drip on the monitor I originally bought on Amazon--just enough in the wrong spot to ruin the monitor, at the dock, within a week of purchase. Even down below, I now wouldn't trust anything less than a marine-grade display, or a water and shock protected tablet. Water gets down below--doesn't matter what you do, it happens. All it takes is an open hatch in a sudden downpour, or an off-watch crew member changing out of soaking wet foulies with the boat pitching and rolling offshore, and that could be enough to do in the monitor.


Running "headless" used to be a risk. When I first installed the Pi, there were times when, after power to the Pi was switched off without a graceful shutdown, the WiFi interface wouldn't start properly the next time the Pi was rebooted, so the only way to get in and fix it was to attach a wired monitor and keyboard. Happily, I've yet to experience this problem since switching to the latest OpenPlotter release and am increasingly comfortable (a) running headless without a backup monitor and keyboard stowed somewhere safe and (b) not worrying too much about the Pi losing power. I'll even switch it off without shutting it down, sometimes, if I'm at the dock and I know I can recover the Pi at my leisure if I have to. Not that I recommend it.....



John Clark
Toronto, Ontario, Canada

Originally Posted by Dsanduril

We have been using a Pi 3 as our primary navigation tool for 3 years and one lap around the globe. We run the OpenPlotter install that includes OpenCPN, SignalK, and a bunch of other goodies. PyPilot is on the list of possible upgrades.

Overall we love the Pi and OpenPlotter. A couple of small items:

1. Get a really good 5V power supply that is capable of supplying the required current (which varies depending on Pi model). These are cheap (12V-5V) but very necessary. Find one that outputs 5.25V if you can, that is the top end of the Pi spec and allows for some voltage drop.
2. Get a really good USB power cable, as short as possible, to connect your Pi to the power supply. USB cables aren't great for supplying power, but there are a few out there with larger power conductors that will help limit the power drop.
3. Use a quality SD card.
4. Get a decent case for the Pi. This may set you back nearly as much as the unit itself. But the naked Pi board is a bit delicate - put it in a good case. That also helps keep the moisture at bay.

We use OpenCPN to provide routing information, display grib files, drive the autopilot (a Raymarine at the present moment), and just general navigation.

We use SignalK to run some web dashboards that allow us to see the instrument values (and some OpenCPN computed data) from tablets connected to WiFi anywhere on the boat. We occasionally also use the built-in VNC server to allow us remote views of the charts, but for that we usually just turn on the monitor (we normally run with the monitor off to save electricity).

Power usage averages about 4W (~0.33A @ 12V) so about 8Ah/day.

Can't say enough good things about both the hardware and the software.

[mikedefieslife]

Originally Posted by benet250

Google 'wear level on sd card's' for a good explanation on how sd card's 'wear out and what to get, also openplotter will not run on RPi4, the RPi3B is the one to get,

Originally Posted by Dsanduril

At the commercial/household level SD and SSD are both NAND flash memory and they both suffer from wear. Again at the commercial/household level each bit of NAND can generally be written ~1000-3000 times. There are NAND technologies out there (pSLC, SLC, etc.) and other non-volatile memory products that have significantly higher write cycle life, but are also so much more expensive that they don't show up too often in everyday use (a 32GB pSLC SD card runs $50-$100 while the same in typical MLC form from a quality brand is < $10, from a cheap brand it may be significantly less than that).

The life of both an SD card and SSD can be extended by two common techniques:

1. Wear Leveling - a controller on the drive/card evens out the wear so that every bit sees the same amount of usage.
2. Over-provisioning - you get a 32GB device but format it to only use 25GB and reserve the remainder as replacement/spare space to be used when one part starts to wear out.

For the everyday user you don't see these things, but there really is very little difference between an SD and SSD. The key is in the wear-leveling algorithms in both devices (and yes, there can be a wear-leveling controller inside that tiny microSD card). If the OpenCPN logfile is allowed to write to the exact same memory block every time it writes (or the config file, or whatever) then it is not hard to wear out that block and to corrupt the file system doing so. Cheap NAND devices may have bad wear-leveling algorithms (or none at all), quality ones have better wear leveling. Getting that level of detail out of manufacturer specs is a challenge and so you end up having to go with recommendations from the web unless you want to pony up more $ for the SD card (or SSD drive) than you did for the Pi itself - then you can find genuine specifications on wear-leveling, provisioning, and all the other fun details.

There's no real need to bother trying to extend the life of an SSD. A modern SSD like the Samsungs (which incidentally come with a 10 year warranty), is likely to last nearly 300 years writing 2TB a year before it 'wears out'

Trying to prolong the life of something like that is pointless. Way over the top of those people that baby their batteries trying to get 7.5 years out them rather the 7 they get if just treated them as normal.

My advice would be to use it, enjoy it, have a full backup. Don't waste time monitoring it.

[Dsanduril]

Originally Posted by mikedefieslife

There's no real need to bother trying to extend the life of an SSD. A modern SSD like the Samsungs (which incidentally come with a 10 year warranty), is likely to last nearly 300 years writing 2TB a year before it 'wears out'

Trying to prolong the life of something like that is pointless. Way over the top of those people that baby their batteries trying to get 7.5 years out them rather the 7 they get if just treated them as normal.

My advice would be to use it, enjoy it, have a full backup. Don't waste time monitoring it.

My point is that the same is true of a decent SD card. They're the same technology, have the same wear-leveling and over-provisioning hidden in the background and handled by the manufacturer. At least the decent ones (of both types of devices). So unless you need the space I don't see a huge advantage to having an additional SSD dangling off the Pi. Media center, sure, no other option. But charting, I can handle that all on the SD. YMMV, I'm happy with running off the SD and have not (yet) needed the completely configured backup SD that I carry around.

[Reefmagnet]

Originally Posted by fxykty

Agreed, OpenPlotter V2 beta, which is required for Pi 4, works pretty well. I could t get tides to display, but otherwise all the basics are there.

What do people do to power off? Just use the software shut down command, or also disconnect the power? Is there any need to build a power button?

My Pi sits inside my nav table, so a remote power button would be nice.

Many times, my poor rPi just gets switched off at the power and this doesn't seem to have any ill effect, although occasionally I need reboot it to get the KPlex streams working again. Usually I shut it down from either the nav station pc using Putty or VNC and at other times I use a free application on my Android devices called "Raspi Check" to shut it down. On this latter, everyone should use Raspi Check as it also monitors the perfomance and temperature of the rPI and also provides an extra check to ensure a headless unit is online.


Whilst mentioning KPlex and Raspi Check, I had a rather interesting experience recently with my rPI. I decided to change the KPlex NMEA output for OpenCPN from a TCP stream to a UDP stream via the OpenPlotter configuration console. I changed no other settings other than the changing from TCP to UDP. This configuration was active for most of the day. Just by coincidence, I was showing my dock neighbour the Pi setup (which sits on top of my VHF) that night and it was extremely hot to the touch. I'd never noticed this before and after checking with Raspi Check I could see that the core temperature was 82C (the maximum a Pi 3 will reach before it self protects) and the load was in excess of 80%. Because I always use Raspi Check, I could see straight away that this was out of the normal range I usually see which is a core temperature of typically around mid 60C and 20% load at worst.



A quick experiment with changing from UDP back to TCP revealed that it was this change that caused the excessive load. A change to TCP quickly reduced load to the expected lower levels. I suspect that the issue is arising from the Pi broadcasting UDP packets continuously rather than on demand as TCP would entail. Based on this observation, I'd suggest sticking with TCP if using kPlex for multiplexing.

[Eight Sails]

That should have read "Kplex" not "SignalK." It's been a while.

Regarding OpenPlotter performance on an older Pi, I should also admit that I don't really use the copy of OpenCPN installed with OpenPlotter on the Pi very much. I mainly use the Pi as a WiFi data source for OpenCPN installed on other laptop, tablet or smartphone devices, so the performance I notice most of the time is the native performance of an OpenCPN app running on those devices, not on the Pi.

[QUOTE=Eight Sails;3061637] I installed OpenCPN and SignalK on a Pi 2B a number of years ago, back when that was the latest and greatest setup and OpenPlotter wasn't yet available to make things easier. I'm still using the Pi 2B hardware but did a clean install of the OpenPlotter package on a fresh SD card when upgrading. No more hand editing Linux scripts and configuration files--much better now!

[thomm225]

So just for others who may have had problems downloading openplotter, I'll explain my problems.

The latest openplotter download wouldn't extract from zip on my computer after I downloaded it

The sd formater would sometimes only format to 30 mb or so

At one point after multiple tries to load anything my raspberry pi 4 wouldn't boot at all. (formatter finally worked)

So I investigated online and it said if the green light blinks 4X your hardware is good.

But I still couldn't get files loaded to my sd card without it showing they were corrupted.

So finally I downloaded a good sd formatter and a good zip file extractor.

Then I loaded Raspbian buster lite and it booted up ...... to the login prompt in terminal mode. So the login in is pi then it wanted a password which was raspberry. Then it gave the normal prompt.

So I found it needed to be configured for gui but since I had loaded buster lite those files weren't there.

So I loaded Raspian Buster w/desktop. That loaded and worked. (with gui screen)

now I have loaded openplotter. The latest one and it worked.

So my problem was my old Sd Formater and my old zip extractor, and I also used win32imager which worked after I had the updated formater and extacter!!

Before that it was corrupted this and will not extract that.

And lastly sometimes my sd card had to be reseated in the usb card reader

As I said earlier this project was partly to get reacquianted with newer technology and it has definitely done that.


Now the charts download and come up on OpenCPN just like they did on Windows with my other computers before I bought the Raspberry......

[mikedefieslife]

Originally Posted by thomm225

So just for others who may have had problems downloading openplotter, I'll explain my problems.

The latest openplotter download wouldn't extract from zip on my computer after I downloaded it

The sd formater would sometimes only format to 30 mb or so

At one point after multiple tries to load anything my raspberry pi 4 wouldn't boot at all. (formatter finally worked)

So I investigated online and it said if the green light blinks 4X your hardware is good.

But I still couldn't get files loaded to my sd card without it showing they were corrupted.

So finally I downloaded a good sd formatter and a good zip file extractor.

Then I loaded Raspbian buster lite and it booted up ...... to the login prompt in terminal mode. So the login in is pi then it wanted a password which was raspberry. Then it gave the normal prompt.

So I found it needed to be configured for gui but since I had loaded buster lite those files weren't there.

So I loaded Raspian Buster w/desktop. That loaded and worked. (with gui screen)

now I have loaded openplotter. The latest one and it worked.

So my problem was my old Sd Formater and my old zip extractor, and I also used win32imager which worked after I had the updated formater and extacter!!

Before that it was corrupted this and will not extract that.

And lastly sometimes my sd card had to be reseated in the usb card reader

As I said earlier this project was partly to get reacquianted with newer technology and it has definitely done that.


Now the charts download and come up on OpenCPN just like they did on Windows with my other computers before I bought the Raspberry......

You would have saved a lot of time just downloading the image I posted. It is deafult raspbian buster with Openplotter-settings installed, so you just then install the aspects of openplotter that you want, all from the GUI.

Of course you wouldn't have learned anything that way though

[thomm225]

Originally Posted by mikedefieslife

You would have saved a lot of time just downloading the image I posted. It is deafult raspbian buster with Openplotter-settings installed, so you just then install the aspects of openplotter that you want, all from the GUI.

Of course you wouldn't have learned anything that way though

As I said above, the downloads wouldn't unzip.

It's sort of hard to load a file that will not unzip and when it tries to unzip it would say file corrupted or destination file unavailable or some such

I could have downloaded your file (thanks btw) forever but unless I finally decided to get a decent zip extractor (7 zip) it would never have worked.

On top of that, the formatter on my computer often tried to format at the boot load size like 256m or 30 m.

So unfortunately for me I got the good formatter first which cause my raspberry not to boot at all.

I just looked back at your post and I did try that mega file but it was no longer available

All's well that ends well though and I did a couple loads on the latest openplotter zip and it works great!

I have downloaded charts for the Bay to 80 miles North, Atlantic Ocean out 15 miles of so, and the ICW to North Carolina