A challenge to make a cheap plotter for under £60

[vas]

In my quest to find the cheapest plotter, I managed to bag/buy one of the new Raspberry Pi Zero 2Ws
They have just been released and are already sold out.

The Raspberry Pi Zero 2W is a "drop in" replacement for the old Raspberry Pi Zero and is between 4 to 6 times faster than the old model.
But, disappointingly, they don't have much RAM which makes them slower than they could have been if they had more RAM.
That said, they retail at £13.99 inc VAT.
The board incorporates a quad-core 64-bit Arm Cortex-A53 CPU, clocked at 1GHz and has USB and HDMI connectors.
Very low power with WiFi and Bluetooth interfaces on board.

As usual, it runs the Raspbian/Raspberry Pi Operating system which is a derivative of Debian Linux.
I was disappointed that it doesn't yet run my favourite Manjaro operating system that I use on all my other devices (the Raspberry Pi 4 does run Manjaro - 64 bit)

Here is a pic of the Raspberry Pi Zero 2W beside a pen to show just how small it is.

View attachment 125478

And this time, I treated it to a case:-

View attachment 125479

Mike,

as you don't tend to zoom in and out all the time (and that's where CPU is mostly needed to scale and render new screens) I'd say that the above is acceptable and quite similar (on the low side...) rendering speed to a 15-20yo plotter
consumption is minimal, issue and the main reason we mostly use dedicated plotters under the sun, is the sun and the rain/spray...
doesn't look to be a big enough market for sun viewable, IP60lot 10-15in screens for the companies to invest and built something decent

 

[Hurricane]

Mike,

as you don't tend to zoom in and out all the time (and that's where CPU is mostly needed to scale and render new screens) I'd say that the above is acceptable and quite similar (on the low side...) rendering speed to a 15-20yo plotter
consumption is minimal, issue and the main reason we mostly use dedicated plotters under the sun, is the sun and the rain/spray...
doesn't look to be a big enough market for sun viewable, IP60lot 10-15in screens for the companies to invest and built something decent

I agree 100%
And, yes, the cheap Raspberry Pi Zero 2W (the new one) COULD do the job - especially for those looking for a really cheap system.
But once you have used OpenCPN on a proper desktop PC, you will realise just how good it is.
As you say, old 15 to 20 year old plotters are way slower than a modern solution and probably comparable to the 14 quid Raspberry Pi Zero 2W

Under OpenCPN, the type of chart that you use can have an effect.
For example, I made some MBTILE format of charts which work well on a normal PC but are hopeless on the Raspberry Pi - I think because the RAM is limited on the RPi.
However the vector charts that I have (CM93) seem to be acceptable on the Raspberry Pi.
It would be interesting to hear how well the oeSenc charts work on a Raspberry Pi.

 

[Hurricane]

I've just tried increasing the Raspberry Pi Zero 2W's swap file.
Swap files are located on the drives (in this case, a microSD card) and used when the on board RAM reaches its limit to extend the effective size of the available RAM.
It has made a bit of a difference - slightly faster - fast enough to switch the Raspberry Pi Zero 2Ws screen back to 1K (1920x1080) and still have a usable plotter.
Interestingly, the microSD card isn't the fastest device.
It is possible to boot from (and use) a faster USB device so I might try connecting an SSD sometime and see how it performs.
Tweaks like this sometimes make a huge difference - it would be interesting if that kind of thing works in this case.
Just for interest but some people might find this kind of thing worth installing.

 

[Hurricane]

I've just set up a cheap 20 quid SSD (120Gb Western Digital Green).
I copied the operating system onto the SSD and booted it using the Raspberry Pi Zero2W.
Not a huge difference in the speed that OpenCPN runs but it is really impressive that a cheap £14 package can work that well.
You could use it as a desktop PC - after all LibreOffice is free and there is loads of other open source software out there.
Really impressive.
Of course, the Raspberry Pi Zero range isn't supposed to run a full GUI desktop system.
It is mainly designed to run dedicated IoT style applications.
It has the full Raspberry Pi expansion digital I/O header so it should be able do all kinds of control jobs in its stride.

EDIT
Here's a pic - might help people understand the SSD setup

 

[chrisharris]

Sounds like my kind of set up.
It will be interesting to hear what "high brightness" monitors you are suggesting or what you end up fitting.
In my case. I have an expensive Raymarine G series glass bridge navigation system.
Each of my 4 displays are NOT plotters - they are monitors so I have always used the VGA inputs into those monitors.
A solution that works for me but when friends show interest in using OpenCPN, it would be nice to be able to recommend a "high brightness" monitor.

This is one of my Raymarine displays connected to a PC running OpenCPN - a few years ago - OpenCPN has been upgraded quite a bit since then.

View attachment 125511

This photo shows a real situation - and just how good the AIS feature within OpenCPN is.
It is dead easy to work out what is happening in this display.
The classic - will I pass in front or have to go behind?
In the case of motorboats, it is often just a matter of adjusting the speed.

View attachment 125512

I agree the sunlight viewable monitors are the most difficult bit to find. I have tried a variety of options, from basic laptop screens, ELO touchscreens, specific marine monitors etc. The best I have found so far have been industrial bare screens. I bought one from a manufacturer in Taiwan, it's a 10.4 inch 1500nits display, which is genuinely usable in bright sunlight. Limitations were the size, and it was a bare unit so I had to build an enclosure to keep it dry. Worked well for last few yrs. I have just bought a bargain Litemax 15 inch (slo1568-e) from eBay, it's a 1600nits display, with DVI input. Again I will need to build an enclosure but have a NavPod as a starter. I also have a number of 12 inch screens I bought some time ago with a plan to replace the engine instruments on the flybridge with a couple of screens (need to convert the instrument feeds as well).

 

[chrisharris]

I've mentioned before that I am another convert to OpenCPN, and it really is very good. Our set-up is a lot more expensive because it's built round a Vasari PC running Windows 7 and displaying on 3 monitors at the helm including a 21" AG Neovo which is superb. I would hate to have to go back to anything smaller than that, I've got so used to having a big screen. Like chrisharris I use a Panasonic Toughpad as the flybridge monitor, held in a RAM suction-mount so it can be moved to always face away from the sun.


How do you link the Toughpad at the moment?

Like Hurricane I will be very interested to know about your high brightness monitor. After a lot of research I have come to the conclusion that when you buy an off-the-shelf system from Raymarine, Garmin, etc. a lot of the money is going on the high brightness waterproof monitors.

I just use VNC to access the Pi from the toughpad. It's simple and does what I need. The biggest problem is accuracy of using the touch pen at sea!

 

[Hurricane]

I just use VNC to access the Pi from the toughpad. It's simple and does what I need. The biggest problem is accuracy of using the touch pen at sea!

I assume that you are accessing the Pi through a remote desktop application.
Rather than VNC, have you tried NoMachine - it is a great solution for devices on the same LAN.
Fast and in my experience much easier to set up than VNC.
NoMachine has versions for all operating systems.
Free to use for non-commercial users.
I use it on all my systems including remote access to the boat through a secure tunnel.
And a great way to manage a "headless" server.

 

[chrisharris]

I assume that you are accessing the Pi through a remote desktop application.
Rather than VNC, have you tried NoMachine - it is a great solution for devices on the same LAN.
Fast and in my experience much easier to set up than VNC.
NoMachine has versions for all operating systems.
Free to use for non-commercial users.
I use it on all my systems including remote access to the boat through a secure tunnel.
And a great way to manage a "headless" server.

Many thanks, I will have a look, that sounds a better option.

 

[Hurricane]

Many thanks, I will have a look, that sounds a better option.

Perhaps I should add that I don't use specific server software on my servers.
I just use a normal desktop distribution (Manjaro Linux these days) that has its usual GUI desktop to share drives etc.
NoMachine allows me to connect to any of my desktop computers (including the desktops on my servers) and run GUI software as though I was actually at that computer's desktop.
The same thing could be done by connecting to a Raspbery Pi desktop from any other device/operating system.
NoMachine is independent of the internet so can be used on a boat at sea.
As I say, much easier than VNC.

Another very interesting remote desktop software is DWSERVICE - see here DWService - remote access, remote administration, remote support
Again this software runs on lots of different operating systems.
The big difference in DWSERVICE is that you can access your computers from anywhere - it effectively "tunnels" through the NAT firewall of your router thus providing access to your computers outside your LAN.
Another big feature of DWSERVICE is that you connect to your computers using a standard web browser.
So, wherever you are, you only need access to an internet browser and you can connect to the desktop of any of your computers.
Not much help on a boat at sea because it uses the internet but could be useful for other applications.

 

[TwoHooter]

The biggest problem is accuracy of using the touch pen at sea!

Yes! How on earth do people use touchscreens in rough weather?

NoMachine is independent of the internet so can be used on a boat at sea.

Thanks for the recommendation. This morning after reading your post I installed NoMachine on my ship's computer and the Panasonic Toughpad and it seems OK. Then I switched the Router WAN off leaving only the LAN, proved the LAN had lost its internet connection, and NoMachine still worked. Terrific! Bye Bye Splashtop.

Next bullet to bite is Linux, starting with a new portable computer to take over from my ageing laptop. Only about 4 years late (that's when Hurricane ran his Linux course). Better late than never. Not really relevant to this forum until I change the ship's computer.

But this is relevant:- Linux on the boat will mean I lose access to my Admiralty raster charts from Visit My Harbour. I'm not looking forward to that. I don't trust vector charts. I've seen too many instances where selecting the wrong zoom level can mean you don't see important things. I suppose I could create my own raster charts like Hurricane does but I would never be able to keep them up to date whereas the VMH charts are updated annually. I spoke to VMH and they have no plans to support Linux. I think one should choose a chart system before choosing a navigation system - for example I bought Coastal Explorer for the boat but that only runs C-Maps and I have found them to be very poor quality (as have some others in our Owners Goup), so I never use it. I will be breaking my own rule unless the VMH charts will run in a Windows emulation on Linux and still enable routes to be created for the autopilot (my policy is to let the route steer the boat unless I have to deviate for traffic etc.).

 

[Forty_Two]

I'm using a Pi4b 4GB which works well for me with OeSenc charts. I use a 21.5" Samsung TV at the Helm & Android tablet on the Fly Bridge via. Vnc. If the sea state is less then "perfect" I'm downstairs anyway so the touch issue doesn't bother me. Used it throughout the 21 season & not a single problem, very impressed with the setup. Using OpenPlotter2 with Ocpn5.2. Bear in mind I only cruise at 8Kn.

I tried an SSD on the Pi but was no faster, to gain speed you need a M.2 NVMe interface rather than Usb3 i think.

I actually prefer the SD card as it's so easy to keep spares to hand in case of an issue & fast to make copies with a second reader/writer plugged in to Usb3. I use a dongle for the charts so no issue with changing SD card or hardware. I do like having several spares to hand of all the system parts.

 

[Hurricane]

Yes! How on earth do people use touchscreens in rough weather?

Thanks for the recommendation. This morning after reading your post I installed NoMachine on my ship's computer and the Panasonic Toughpad and it seems OK. Then I switched the Router WAN off leaving only the LAN, proved the LAN had lost its internet connection, and NoMachine still worked. Terrific! Bye Bye Splashtop.

Next bullet to bite is Linux, starting with a new portable computer to take over from my ageing laptop. Only about 4 years late (that's when Hurricane ran his Linux course). Better late than never. Not really relevant to this forum until I change the ship's computer.

But this is relevant:- Linux on the boat will mean I lose access to my Admiralty raster charts from Visit My Harbour. I'm not looking forward to that. I don't trust vector charts. I've seen too many instances where selecting the wrong zoom level can mean you don't see important things. I suppose I could create my own raster charts like Hurricane does but I would never be able to keep them up to date whereas the VMH charts are updated annually. I spoke to VMH and they have no plans to support Linux. I think one should choose a chart system before choosing a navigation system - for example I bought Coastal Explorer for the boat but that only runs C-Maps and I have found them to be very poor quality (as have some others in our Owners Goup), so I never use it. I will be breaking my own rule unless the VMH charts will run in a Windows emulation on Linux and still enable routes to be created for the autopilot (my policy is to let the route steer the boat unless I have to deviate for traffic etc.).

Yes, I can't understand how people manage to use touch screens at sea - on a trip last year to Mallorca delivering a Sealine with a touchscreen plotter, I spent most of my time swearing at it because every time I wanted to make an adjustment, I seemed to press the wrong part of the screen.
The best solution I've found is the controller that I have on my boat - Raymarine wireless controllers that you hold in your hands and as a result, you don't inadvertently press the wrong button as the boat moves.
These are the ones that I have:-

Linux Starting Point
I suggest that you start with the Manjaro Linux distribution.
Virtually all the applications can be installed using the Pamac Package Manager which had a GUI and is dead easy to use.
For example, OpenCPN needs to be compiled but Pamac automatically does all this with a click of a button.
We used the Linux Mint Distribution when we did that workshop 4 or 5 years ago but I think Manjaro is a bit more intuitive.
I suggest that you give it a try anyway.
Let me know if you have any questions.

Visit My Harbours Charts for Linux
What software do you use for the VMH charts?
IIRC, VMH used to supply charts that were compatible with the Memory Map software.
It may be possible to run whatever software you use under Wine which enables Windows applications to run under Linux.
For example, I run Photoshop for Windows and the Reolink cameras on my Lunux machines using Wine.

 

[Hurricane]

I'm using a Pi4b 4GB which works well for me with OeSenc charts. I use a 21.5" Samsung TV at the Helm & Android tablet on the Fly Bridge via. Vnc. If the sea state is less then "perfect" I'm downstairs anyway so the touch issue doesn't bother me. Used it throughout the 21 season & not a single problem, very impressed with the setup. Using OpenPlotter2 with Ocpn5.2. Bear in mind I only cruise at 8Kn.

I tried an SSD on the Pi but was no faster, to gain speed you need a M.2 NVMe interface rather than Usb3 i think.

Be aware that the 64bit OeSenc module hasn't yet been released so stick to your 32bit build for the moment.
Raspberry Pi Os has recently (in the last few days) been upgraded to Bullseye Debian but the Raspbery Pi Os people are sticking with 32bit and have only released Beta versions of the 64bit system.
Maybe the OpenCPN team will catch up and release a 64bit oeSenc module soon.
The above oeSenc note only applies to ARM processors(Raspberry Pi) - everything works (including oeSenc) for the faster 64bit PCs

M2, NVMe
If you can, it is worth building these very fast SSDs into the PCIe interface rather than SATA.
The Raspberry Pi project is a bit slow developing interfaces for PDIe devices.
I'm not sure that the Pi 4 even allows access to the PCIe - you may need to use a Raspberry Pi Compute Module 4 to get access to the PCIe interfaces.
But when we do get full PCIE access, I suspect that the Raspberry Pi will be way quicker.

 

[TwoHooter]

I do like having several spares to hand of all the system parts.

This was why I went for a computer-based system running OpenCN instead of an off-the-shelf product from one of the usual suspects. I really like the fact that no marine electronics tech is ever going to tell me that my whole system must be ripped out because a single component has failed and it's obsolete and no they don't do spares anyway.
BTW your system looks very good and we too are only on the flybridge in good weather unless it's night and we are in a pot-infested area.

What software do you use for the VMH charts?

Our Operating System is Windows 7, as mentioned.
The VMH charts are on a stick plugged in to a USB port. The stick has Trust Cont Ltd, IP protection built in.
After booting the computer into Windows I tell it to access the VMH charts and a short routine runs.
I then boot OpenCPN - on the first use of a new VMH chartstick it has to update the chart database but after that I never have to think about the charts again.
I haven't yet tried running OCPN with VMH Admiralty raster charts in one window and a vector chart in another.

As a sidenote, I really must make a donation to the OCPN project. I now have a small annual budget for donations to the free software I use, which is almost everything nowadays. I stopped using Microsoft Office years ago and I got rid of Dropbox this year when I discovered how useless it is in an emergency. I think the only paid-for services on my systems are my hosting package (annual subscription), VMH charts (every 2 years), ESET malware protection (annual), Coastal Explorer (one-off payment), & Display Fusion (one-off payment).

 

[TwoHooter]

I forgot the other big thing about monitors which you get from the marine electronics companies - screen dimming.
No point in having a really bright sunlight-readable screen at night!
I use Display Fusion to dim my monitors at night.
What do others use?

 

[Hurricane]

I forgot the other big thing about monitors which you get from the marine electronics companies - screen dimming.
No point in having a really bright sunlight-readable screen at night!
I use Display Fusion to dim my monitors at night.
What do others use?

I don't think there is a version of Display Fusion for Linux.
Probably because xrandr under Linux does everything that Display Fusion does for Windows.
With multiple monitors, I do everything I need with the standard Linux environment (X Server).
On the boat, I reduce the brightness control on the Raymarine display at night so there isn't a need for the PC to have control over brightness.

In the Linux world, there is a huge development currently going on to replace the X Server windows manager with a complete rewrite called Wayland.
This will take many years to finalise but in the meantime, X Server does everything we want (and more).

 

[Hurricane]

This was why I went for a computer-based system running OpenCN instead of an off-the-shelf product from one of the usual suspects. I really like the fact that no marine electronics tech is ever going to tell me that my whole system must be ripped out because a single component has failed and it's obsolete and no they don't do spares anyway.
BTW your system looks very good and we too are only on the flybridge in good weather unless it's night and we are in a pot-infested area.


Our Operating System is Windows 7, as mentioned.
The VMH charts are on a stick plugged in to a USB port. The stick has Trust Cont Ltd, IP protection built in.
After booting the computer into Windows I tell it to access the VMH charts and a short routine runs.
I then boot OpenCPN - on the first use of a new VMH chartstick it has to update the chart database but after that I never have to think about the charts again.
I haven't yet tried running OCPN with VMH Admiralty raster charts in one window and a vector chart in another.

I have just tried the VMH test chart under Wine and it doesn't work.
If you could get the VHM charts into a proper BSB format, they would work under OpenCPN in any operating system.
But, for obvious reasons, they won't do that.
Years ago, I used to get QCT (Memory Map) charts from places like VMH.
I wrote some software that converted the QCT formats into .KAP (BSB) which work with OpenCPN (on any operating system)
But then they changed the QCT format into an encrypted format and I haven't looked at that since.

 

[snowbird30ds]

I have a load of old OS qct maps I'd like to try in opencpn, any chance of a copy of the converter program please?

 

[TwoHooter]

I know this thread is supposed to be about cheap plotters but I think it is also highlighting the two reasons why open source navigation systems have never caught on in a big way.

First, charts. When OpenCPN started everyone was using "stolen", ie: breach of copyright charts. There was a sort of underground supply of these, swapped between the yachts (they were nearly all yachts). That problem has pretty much been solved for many of the most popular cruising areas by o-charts | Charts for OpenCPN It still leaves out people like me who prefer raster charts but I'm in a tiny minority.

The second, and much bigger problem, is monitors. We need waterproof sunlight-readable screens for flybridge use, and dimming for night use whether at the helm or on a flybridge.

Does anyone on here follow the principal OpenCPN forum, which is part of Cruisers Forum? I know the monitor issue has been discussed there in the past.

As for Linux, I think a lot more people would use it if it were not for the fact that nearly everyone who is likely to consider it has some favourite bit of legacy software which will not run in Linux, and often won't run in something like WINE, as Hurricane has just found out with my VMH charts. I've decided not to let that stop me from converting to Linux.

 

[Hurricane]

I've decided not to let that stop me from converting to Linux.

I'm sure you will find a way round and do it in the end.