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HOWTO.md

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From scratch

An example: how to setup a new Raspberry Pi for a minimalist Nav Station.

We will be setting up a Raspberry Pi Zero W with an e-ink 2.13" bonnet.

The e-ink technology is quite interesting here, in the sense that it consumes energy only when updating the screen. Once something is displayed on the screen, you can pull the plug, whatever's displayed remains displayed.
As you would see below, there is a web interface that can be used to see - among others - the data displayed on the screen. But having the screen allows you not to use any other device to get to the data.

In the use-case presented here, the NMEA-multiplexer will:

  • Read a GPS
  • Log the data into a file
  • Display the data on the e-ink screen
    • The two buttons on the screen's bonnet can be used to scroll through the available data
  • Broadcast the data on TCP:7001
  • Host Web Pages to display the data, manage the system, manage the log files.

The server (aka Mux) will be automatically started when the Raspberry Pi boots. In this example, the multiplexer is driven by the configuration file nmea.mux.gps.nmea-fwd.yaml.

We do the build on one machine, where the git repo has been cloned, and we deploy on the Raspberry Pi only the parts required at runtime. The build is a demanding operation, the Raspberry Pi Zero could do it, but it would indeed take quite some time. A more powerful machine is more suitable for this kind of process.
The process goes in two main big steps (also summarized here).

  • Step One: you clone this repo, do the build, and package for deployment.
    • This step requires a bit more resources than the next one.
    • You will need an Internet connection, a keyboard and a screen.
  • Step Two: you setup the Raspberry Pi, and make it ready for duty.
    • You start from a freshly flashed SD card, setup the system to emit its own network, install the required softwares and configure them.
    • Configuration steps will require an Internet connection.
    • Once the configuration is completed, the Internet connection is not required anymore, ssh and scp will do the job.
      • Note: VNC could also be an option to access the Graphical Desktop running on the Raspberry Pi. But this could be too demanding for a Raspberry Pi Zero... To enable it, use raspi-config on the Raspberry Pi, to boot to Desktop, and start the VNC Server.

So, let's go.

  • Use Raspberry Pi imager to flash a new SD Card
    • Make sure SSH is enabled (it's a setting parameter in the Raspberry Pi imager).
    • Create a user named pi (this is the name we use below, choose your own if you want to)
  • Use the script ./to.prod.sh to package the current software. This step happens on the machine you've cloned the repo on.
    • Warning: For the build, do make sure you use a JDK (Java Development Kit) compatible with your target!
      If you've installed a JDK8 (see below) on the Raspberry Pi, do the build with a JDK of the same version!
      Using a JDK11 for the build will not work at runtime on a JDK8.
    • Make sure you package the Python part as well, when prompted.
    • This will prepare a tar.gz archive, called - for example - nmea-dist.tar.gz (you choose the name nmea-dist during the build process).
    • Send the archive to the newly flashed Raspberry Pi (change it's IP address at will)
      • scp nmea-dist.tar.gz [email protected]:~
        where nmea-dist is a name chosen by you during the execution of the to.prod.sh script, pi is the username you chose too, and 192.168.1.15 is the IP Address of the Raspberry Pi, obtained with an ifconfig on the Raspberry Pi, or a fing on any machine on the same network as the Raspberry Pi.
  • Log on to the new Raspberry Pi, to prepare the new system. This will require an Internet connection.
    • Using sudo raspi-config (or its desktop equivalent, Preferences > Raspberry Pi Configuration):
      • Boot to Command Line Interface (CLI), Desktop is not required.
      • Make sure SSH is enabled.
      • Enable interfaces SPI, I2C, Serial Port
    • Install Java and other required parts
    sudo apt-get update
sudo apt-get install openjdk-8-jdk-headless
    JDK8 will work on any Raspberry Pi I know.
    Some Raspberry Pi Zero W would not support JDK11, but as long as you know what you're doing, you can install it using: 
    sudo apt-get install openjdk-11-jdk
    • LibRxTx (optional, skip it if you don't know it)
    sudo apt-get install librxtx-java
    • Install required Python modules (if any), like here, for example (for the e-ink bonnet)
    sudo pip3 install adafruit-circuitpython-epd
    • Setup Hotspot (if needed), as explained here.
    • Expand the archive, using a command like tar -xzvf nmea-dist.tar.gz
    • Modify the /etc/rc.local to start the server when the server boots, and issue the required command (links, maps, stty, etc). There is an example in rc.local.use_case.3.sh.
  • Plug in the GPS and the e-ink screen, and give it a try (see for example the script start.all.sh)
  • Try the web interface
    • From a browser on another machine (laptop, cell-phone, tablet, ...), connected on the Raspberry Pi's network, reach http://192.168.50.10:9999/zip/index.html, and see for yourself!

Now, you're good to go, the Raspberry Pi should not need an Internet connection anymore.

About the modification of the /etc/rc.local script, to start the required components when the machine boots, here are the lines to add to the file, before the exit statement at the end:

#
# "Link" the Serial Port
stty -F /dev/ttyACM0 raw 4800 cs8 clocal
#
# Start MUX and Co on startup
#
# Start the REST Server for EINK2-13
/home/pi/nmea-dist/python/scripts/start.EINK2-13.REST.server.sh --interactive:false  --machine-name:localhost --port:8080 --verbose:false --data:NAV,POS,SOG,COG --screen-saver:on > /home/pi/nmea-dist/eink2-13.python.log 2>&1
sleep 10
# Start the MUX
cd /home/pi/nmea-dist
nohup ./mux.sh nmea.mux.gps.nmea-fwd.yaml &
#

As you can tell: it starts the Python server that takes care of the e-ink display, and starts the mux with the config file nmea.mux.gps.nmea-fwd.yaml, provided here.

Again, the system is now operational, and can be re-booted.

Warning: The data read from the GPS are logged into some log-files. Make sure you download and delete them from time to time..., before they get too big (triggering the message "No space left on device"...). There is a Web page for that (in the embarked Web UI), called "Log Management".
Note: For the log-files not to grow too big, we've excluded some strings from the log, see in the yaml config file:

sentence.filters: ~GGA,~GSV,~GSA

This excludes the sentences concerning the GPS satellites from the log files. They're still available in the cache tough, and can be displayed in some Web UI packaged in the archive we've generated.

3D Printed enclosures

STL files available from another repo, here, and here, along with the OpenSCAD code to generate them.
One Two
In its box Connected (Power, GPS)
Three Four
Up and Running Closed
Five Six
Phone UI (the pelican is the screen saver...) Phone UI
SP
Solar powered
  • Other STL files, including a power bank, instead of an external power supply, can be found here.

For the phone UI: the phone is connected to the RPi's network, URL in the browser is http://192.168.50.10:9999/zip/index.html
Note: The phone does not need to have a SIM card.

Connected from OpenCPN through TCP, from a laptop:
Seven

From a laptop, tablet, or cell-phone, Web UI (100% hosted on the Raspberry Pi): Eight

The web UI is customizable at will. Above is an example of the ChartlessMap WebComponent.
In case this is good enough for you, the e-ink screen can become optional.

And as soon as you have a configuration that fits your needs, do make a backup of your SD card... When you need it, this is the kind of things you might regret not to have done.

Consumption

Measured consumption for the config above (with an e-ink bonnet):

Between 0.18 A and 0.24 A

Summary

So, you now have a system that starts at boot.
The Raspberry Pi emits its own network, so you can connect to it from other machines or devices, using ssh, scp, or just http and tcp.

Note: There is a network, but no Internet.
This is not Cloud Computing..., maybe more like "Flake" ❄️ Computing. Very low carbon footprint! The consumption of the setting described above is below ridiculous. I power mine with a solar panel, it's happy as a clam!
A power bank, or a USB Adapter in a 12v cigarette lighter do the job as well.

Current data are displayed on the e-ink screen (basic UI).
It comes with a Web UI, to help you to manage the system, and/or visualize the data (using plain http, as mentioned above).
It also broadcasts the data on tcp, port 7001, so other software can use them, like OpenCPN, SeaWi, etc.
Data are logged into some files, so you can analyze, transform (to GPX, KML, etc) or replay them.

And as no one is going to sell your personal data behind your back, the Web UI does not require any cookie.

Supplies, BOM

The price of the config described here comes to $47.94.

Note: It could be even simpler - and cheaper. The e-ink bonnet is an option. In any case, the system is logging data (in a file), forwarding them (on tcp), and there is a Web interface available through http.
The Python part is not necessary if the e-ink screen is not in the picture.
Without the e-ink screen, the price comes down to $27.99.

Price of the wires and SD card is not included here. I know.
But still 😜.