From 529fffa2ac608a3ac0380534b14d1fa5c11dea08 Mon Sep 17 00:00:00 2001 From: Peter Antypas Date: Wed, 7 Oct 2020 17:16:20 -0700 Subject: [PATCH] README again --- README.md | 41 +++++++++++++++++++++++++++-------------- 1 file changed, 27 insertions(+), 14 deletions(-) diff --git a/README.md b/README.md index e78df97..95f8ab9 100644 --- a/README.md +++ b/README.md @@ -15,22 +15,28 @@ I have refined the design somewhat, and it now has an "official" name, borrowed ### Hardware The main difference between this design and nearly every commercial transponder is that it's a standalone unit. It contains all of its -radios and antennas and thus only needs a power + data cable to connect to the cabin. The PCBA is 1" wide so it fits inside -1" PVC pipe, which I used as the antenna base. The GNSS receiver and antenna are on the board: +radios and antennas and thus only needs a power and data cable to connect to the cabin. The PCBA is only 1" wide so it fits inside +1" schedule 40 PVC pipe, which I used as the antenna base. The GNSS receiver and antenna are on the board: ![Image](images/Board4.3.jpg?raw=True "PCBA version 4.3") -On the hardware side, the design is based on two Silicon Labs 4463 transceiver ICs and an STM32L432KBU6 microcontroller. +The design is based on two Silicon Labs 4463 transceiver ICs and an STM32L4xx series microcontroller (L412 and L432 as of now). The GNSS is a Telit SE873 (7x7mm module) and relies on a Johanson ceramic SMD antenna. It usually takes about a minute to acquire a fix outdoors. -The transmitter output is 2 Watts (+33dBm) and it has a verified range of over 10 nautical miles with a vanilla telescopic antenna (< 3dBi). +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 NMEA0183 data -while listening for CLI commands. Persistent station data (MMSI, call sign, name, dimensions, etc) is stored on a 1Kbit EEPROM and is provisioned via -the CLI. The unit implements SOTDMA synchronization based on the GNSS 1 PPS signal and UTC, but it is a class B, so it will not attempt to reserve slots. It will just transmit independently and autonomously, at the schedule permitted for such transponders. +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. -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 if it is pulled low externally (say via a rocker switch in the control panel). +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. -The circuit draws about 45mA from 12V in RX mode, and spikes up to 600 mA during transmission (for about 30 milliseconds). +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 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. @@ -39,23 +45,30 @@ controls such as "TX OFF". I will include a reference design for a control box t ### 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 not structured around it. +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. ### Building the unit This is going to be difficult for all but the most technically advanced. -The board features mostly surface mounted components, with 5 QFNs, a few SOT-363s and all 0603 passives. Unless you're skilled with stencils and reflow, you won't likely be able to build it. So 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. 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, as every boat is different. +The board features all surface mounted components, with 5 QFNs, a few SOT-363s and all 0603 passives. Unless you're skilled with stencils and reflow, you will find it challenging. + +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. ### License -CAD and firmware are licensed under GPLV3. I chose the most "copyleft" license possible to discourage commercial entities from ripping this off and then "close-sourcing" it. 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 ;) +CAD and firmware are licensed under GPLV3. I chose the most "copyleft" license possible to discourage commercial entities from ripping this off and then "close-sourcing" it. +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 name in your forked designs, as it will be trademarked. +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. ### Concluding thoughts -The commercial AIS industry has not exactly been successful in the low-cost recreational boating market, and with prices like $500-$800 for a unit that needs external GPS (LOL) and VHF antennas that's hardly a surprise. I hope to change that. +The commercial AIS industry has not exactly been successful in the low-cost recreational boating market, and with prices like $500-$800 for a unit that has a bunch of external +dependencies that's hardly a surprise. I hope to change that.