v/maiana
1
0
Fork 0
mirror of https://github.com/peterantypas/maiana.git synced 2025-05-27 21:00:24 -07:00
Code Issues Projects Releases Wiki Activity

More README

Browse Source
This commit is contained in:
Peter Antypas 2020-10-07 17:27:15 -07:00
parent 529fffa2ac
commit abadc5b6ec
1 changed files with 11 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
README.md
View File

@ -25,27 +25,24 @@ The GNSS is a Telit SE873 (7x7mm module) and relies on a Johanson ceramic SMD an
The transmitter output is 2 Watts (+33dBm) and it has a verified range of over 10 nautical miles.
The unit runs on 12V and exposes a 3.3V UART for connecting to the rest of the boat's system. The UART continuously sends GPS and AIS data in NMEA0183 format at 38.4Kbps.
On my boat, it is wired to a control box that converts the UART to USB and feeds it to a Raspberry Pi Zero W,
which acts as a WiFi access point / NMEA distributor for iNavx running on an iPad. There are many different apps and solutions available for this and every boater
has different preferences.
On my boat, it is wired to a control box that converts the UART to USB and feeds it to a RPi Zero W, which acts as a WiFi access point / NMEA distributor for iNavx
running on an iPad. There are many different apps and solutions available for this and every boater has different preferences.
Persistent station data (MMSI, call sign, name, dimensions, etc) is stored on a 1Kbit EEPROM and is provisioned via a command interface.
The unit implements SOTDMA synchronization based on the GNSS 1 Pulse Per Second signal and the UTC clock, but a class B, it will not attempt to reserve slots.
It will just transmit independently and autonomously, based on Clear Channel Assessment, at the schedule permitted for class B devices.
If station data is not provisioned, the device will simply run as a receiver and never transmit. In addition, there is a "TX OFF" signal in the latest design
which will disable transmission explicitly if it is pulled low externally. 6.x and later board firmware has support for this.
The unit implements SOTDMA synchronization based on the very acurate 1 PPS signal from the GNSS and the UTC clock, but being a class B, it will not attempt to reserve time slots.
It will just transmit autonomously and independently, based on Clear Channel Assessment, at the schedule permitted for class B devices. If station data is not provisioned, the device
will simply run as a receiver and never transmit.
The system draws about 40mA from 12V in RX mode, and spikes up to 600mA during transmission (for about 30 milliseconds).
The latest design (not the one pictured above) uses an RJ45 connector, as Ethernet cable is cheap, widely available and offers enough signals to instrument
controls such as "TX OFF". I will include a reference design for a control box that I'm working on but every boat is different, so your mileage will absolutely vary.
The latest design (not the one pictured above) relies on Ethernet cable for power, data, as well as control signals such as "TX OFF". I will include a reference design for a
control box that I'm working on but every boat is different, so your mileage will absolutely vary.
### Software
The firmware is an Eclipse CDT project that you should be able to import and build. It has a BSP architecture so you need to tweak bsp.hpp or define one of
the required symbols in the preprocessor to build for different board revisions. It contains snippets of STM32Cube generated code, but is does not follow ST's spaghetti architecture.
The firmware is an Eclipse CDT project that you should be able to import and build. The code is C++ with a BSP abstraction layer so you need to tweak bsp/bsp.hpp or define one of
the required symbols in the preprocessor to build for different board revisions. It contains snippets of STM32Cube generated code, but is does not follow ST's spaghetti structure.
### Building the unit
@ -55,7 +52,7 @@ The board features all surface mounted components, with 5 QFNs, a few SOT-363s a
I am going to make it available as part of a kit (probably on tindie.com). The kit will include a 95% finished PCBA as well as the VHF antenna,
enclosure and sealing components (which are NOT open sourced). The board will be programmed and tested, and the antenna will be perfectly matched. The cable and whatever lies on the
other side of it will be the end user's responsibility.
other side of it will be the buyer's responsibility.
### License
@ -63,7 +60,7 @@ CAD and firmware are licensed under GPLV3. I chose the most "copyleft" license p
So don't try anything fishy, because I *will* find out and then ... well, let's just say you'll be buying me another boat and I have a particular one in mind ;)
If you're a tinkerer and want to further this design while adhering to the GPL, more power to you! Build it, sell it, give it away, do whatever you want to get it out there.
You cannot, however, use the MAIANA™ name in a forked design, as it will be trademarked.
You cannot, however, use the MAIANA™ name in a forked design, as it will be trademarked. Just call it something else.
### Concluding thoughts