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Sailor Hat for Raspberry Pi
#1
Hi, it's me again...

This time, it's about Sailor Hat for Raspberry Pi. I was bugged about having to treat the onboard Raspberry Pi server different from all other marine electronics. Why would I have to shut the Raspberry Pi down manually before flicking off the electronics switch at the electrical panel? I don't want to teach that to anyone who might be borrowing the boat. And why couldn't I power the Raspberry Pi through the NMEA 2000 bus like most other electronics? And why are most Raspberry Pi NMEA 2000 interfaces unisolated, inducing potentially a huge amount of noise to the power and signal wires?

To solve all these issues, I designed the Sailor Hat for Raspberry Pi (SH-RPi in short). SH-RPi is a power management and NMEA 2000 (CAN) interface hat on steroids. The board accepts an 8-32V input and uses a 60F supercapacitor as an intermediate power buffer, providing ample power for controlled shutdowns as well as a buffer for instantaneous peak power use and protection against power glitches. The input current is limited to 0.8A (at 12V), meaning that powering it via the NMEA 2000 bus still complies to the N2K spec.

The CAN interface is isolated and compliant to the N2K spec. It has been designed to use custom GPIO pins for the SPI interface, allowing simultaneous use with SPI displays or e.g. a Moitessier HAT (for the non-RTC version only, due to an I2C address clash with the RTC chip).

The design is all open hardware and open source with designs and software available at GitHub. See the documentation site for more information. I also have waterproof enclosure kits available at hatlabs.fi.

I'd regard the SH-RPi as a perfect companion for OpenPlotter: it solves all power management issues for the Pi and provides essential connectivity for your onboard computer. The OpenPlotter device can be powered from the same electronics circuit on the electrical panel as everything else and turned off by flicking the switch. No worries about corrupted memory cards.

Here's a sample photo of a SH-RPi on a Raspberry Pi in a waterproof enclosure, powered via NMEA 2000.

[Image: SH-RPi-enclosure-kit-powered.jpg]
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#2
Very nice. It uses SPI 1 for the CANbus chip? I had hoped to use Pican and Moitessier, but of course they both use SPI 0, if this uses SPI 1 for the CAN, it will be useful.
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#3
(2021-05-25, 03:19 PM)rszemeti Wrote: Very nice.  It uses SPI 1 for the CANbus chip?  I had hoped to use Pican and Moitessier, but of course they both use SPI 0, if this uses SPI 1 for the CAN, it will be useful.

SH-RPi uses SPI 0 but a device tree overlay modification is made to add a third Chip Enable GPIO. Therefore, it doesn't clash with other devices using the same SPI bus. Moitessier's accelerometer uses the same I2C address as the DS3231 RTC chip, though. If you want to use them together, you should get an SH-RPi without the RTC.
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#4
That looks great again.

How long does it take from when the capacitor starts to charge until the raspberry starts to boot?
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#5
(2021-05-27, 08:53 PM)Sailoog Wrote: That looks great again.

How long does it take from when the capacitor starts to charge until the raspberry starts to boot?

I tested that with a stopwatch for you. :-) For a fully depleted supercap, charging takes around 45 seconds. The latest firmware charges the supercap to 2.5V (the maximum being 2.6V) to ensure maximum power capability for the Pi right from the startup.

However, on subsequent startups, the startup time is much faster. After a shutdown of a Raspi + OpenPlotter, the supercap charge level remains at 2.4V, and the startup is almost instantaneous. The supercaps do self-discharge over time, so after a week or two you might have to start from 0V again.
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#6
I've just finished a new tutorial about building an OpenPlotter server with Sailor Hat for Raspberry Pi:

https://hatlabs.github.io/sh-rpi/pages/t...er-server/

Since the tutorial relies heavily on OpenPlotter, I'd appreciate comments, fixes, and improvement suggestions a lot!
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#7
looks good, are you not using the openplotter-can app?
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#8
(2021-05-28, 06:03 PM)Sailoog Wrote: looks good, are you not using the openplotter-can app?

The installer script was written for generic Raspberry Pi OS and is required in any case due to the device tree overlays and daemon installation, so I'd rather stick to generic instructions for this tutorial.

Of course it'd be pretty great if OpenPlotter supported SH-RPi natively and could provide those dependencies out of the box... ;-)
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#9
(2021-05-28, 06:23 PM)mairas Wrote:
(2021-05-28, 06:03 PM)Sailoog Wrote: looks good, are you not using the openplotter-can app?

The installer script was written for generic Raspberry Pi OS and is required in any case due to the device tree overlays and daemon installation, so I'd rather stick to generic instructions for this tutorial.

Of course it'd be pretty great if OpenPlotter supported SH-RPi natively and could provide those dependencies out of the box... ;-)

Your boards are fully open-source so we are always happy to support, promote and recommend these projects. Support for SH-RPI should be added to openplotter-can. We are really busy right now finishing other parts and this should wait a little but any contributions is always welcome.
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