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  • Writer's pictureJohn McDermott

How We Made Resegva

For the end of year it’s a good time to give thanks to the many people and their organisations that have helped us during the last year.  We can also explain how the Resegva system works and what it can do.

Most importantly has been working with Verfacil who are based in Bodmin, Cornwall.  Particularly the enthusiasm of business owner Rob Cartwright and the skill of Alex Cartwright in undertaking the electronics and firmware development.  Almost all of our work has been done remotely from each other and it has been a productive relationship that kept us on track with very few set backs.

Boat monitoring system open showing circuit board
Resegva opened up

The Resegva circuit board does a lot of jobs, this first design helped us to check that all the sub-systems worked well.  On board we have a power management block that takes in 8-32V dc and converts this to 5V and then 3.3V to power the rest of the circuitry.  Also provided is a lithium cell charger interface that can switch between battery and external power without glitches of the processor operation.  This allows the device to operate from the power supply of a boat taking very little power (typically <20mA) and continue operation for several days from an internal battery if the power fails.

The next function of the board is the microprocessor that monitors external signals, measures battery voltage with precision and interface to digital interfaces such as CANbus, MODbus or NMEA2000.  We chose a microprocessor module from Movex because it also provides a LoRaWAN wireless transmitter.  We can use LoRaWAN within a marina to reduce the need for satellite transmissions when the boat isn’t at sea or cruising.  For the very technical the microprocessor module is based on the STM32 which is low power ARM based system that provides a lot of peripheral support and a comprehensive software development environment.

The last main block of functionality is the interface to the Swarm satellite transmitter module.  Conveniently this is provided in a mini-PCIE card format.  The transmitter can require over one amp of power when transmitting - only for a few seconds at a time - so a local 3.3V supply is provided to ensure it has the reliable power required to transmit and receive signals from the satellites that are hundreds of kilometres overhead and travelling at thousands of kilometres an hour.  The Swarm module also contains a GPS receiver that we use to track and locate the boat.  You’ll notice the two coax leads that lead to the side of the enclosure so that external antennas can be fitted.  For the GPS we have an option for an internal antenna, but using an external antenna means it can be placed for the best possible performance and make use of active antennas for even better precision.  The Swarm module transmits in a VHF band at around 150MHz, this is similar to the marine VHF band.  Instead of a long antenna we can make use of a ‘stubby’ antenna to talk to our satellite system which can either be mounted on a rail or with a small magnetic mount.

Our next business partner to give thanks to our Mouse Design who worked closely with us to design a custom enclosure to our requirements.  This was also a great phase of the project.  Instead of using a cheap industrial box that although functional was not very elegant and would look out of a place on a boat.

Key design features of our enclosure are the waterproof seal that ensures the electronics are protected.  The base of the enclosure is screwed to the lid first, this allows the unit to be completely prepared before going aboard the boat.  We have provided an intermediate connector block so that this can be wired as required and  protected within the lid.  The connection to boat signals are completed via a NMEA2000 connector and a wire gland.  The whole unit is then mounted to a suitable panel on board the boat using four bolt positions that are well protected at the corners of the enclosure.  Overall we’re very pleased with the outcome of the design project and looking forward to installing more on boats.

There is more software in the system as we need to decode the data and present it to users.  Our data is first sent to the Swarm satellite system (or via the LoRaWAN network) and we need to collect it next.  For our trial deployment we worked with the Datacake IoT platform which was great for the attractive user interface to display data in a variety of formats.  Datacake also made it easy to integrate to Swarm and LoRaWAN Things Network as we needed to write a small piece of software to decode the raw data. We are able to provide dashboards to trial users with individual private logins to view on a PC or mobile device. Datacake provide a free trial account or a very reasonable monthly fee per device and we’re happy to recommend their platform.

Data display of map with boat location and voltage graphs
Resegva Data Dashboard

Also helpful during the last year has been our membership of British Marine.  We’ve attended the Southampton International Boat Show, Crick Inland boat show and Boatlife at the Birmingham NEC meeting boat owners and marine businesses to discuss what we are doing.  Also a great attendance was METSTRADE in Amsterdam - more about that later.

Heidi Frith of SPC Marine Marketing has been helpful more than can be said, and is well recommended to any other business that is wanting to grow. Other helpful organisations that we want to mention and thank are the Plymouth Marine Laboratory, Aqueduct Marina and Marine Energy Systems in Plymouth.  And our good friends at ESA BIC and STFC at Harswell and Daresbury without whom our project would not have got this far so quickly.

That's the update for this week, more later! Please do get in touch if you want to know more about the Resegva system.

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