Having discovered that there are GPS 'dongles' that plug into the USB
port - readily available for $10-ish, I decided to pick up my old A+ and
do the thing. I have a 5" hdmi touchscreen on it for display, so no kbd
or mouse needed.You can actually just capture the GPS output from one of
the tty ports, but I wanted more than that so installed gpsd and
foxtrotgps and we're good to go. With that in place and lxde running,
about 2/3 of memory is used, so I'll go with twm - that more than cuts
memory usage in half. Plan is to move it over to a zero. I have a fairly
good capacity power bank to use it with.
On a sunny day (26 Jul 2018 21:03:17 GMT) it happened ray carter
wrote in :
Only restriction on using /dev/ttyUSB* is that if you plug in / out
serial devices the kernel can renumber things.
Raspi has a real serial port on /dev/ttyAMA0 accessible via 2 GPIO pins.
Many GPS modules come with logic level serial out.
This stuff I wrote uses /dev/ttyAMA0
On a sunny day (Fri, 27 Jul 2018 13:17:43 +0100) it happened "NY"
wrote in :
No, not hot-pluggable.
Very likely you will kill the chip if you try that.
Static electricity, voltage levels above 3,3. V, wrong connection sequence,
my remark was more for when you design a board.
Also some electronics knowledge is required to interface to those pins.
There are also hats', but quite pricey:
No connection with them, I do see they copied the idea of my little sensor board
with compass, and accelerometer ;-)
There is a whole team working on that boat navigation stuff,
charts are available, there is also opencpn (I have that).
Probably much more.
For me it is the fun of writing the code, understanding in depth how GPS etc works,
and designing the hardware.
I have an electronics background, so should not make those mistakes (killed one raspi nevertheless by shorting 5V to a 3.3V pin).
If you come more from the user perspective, then stay with the USB thing you have, I have modified some GPS modules
by adding an ebay module for serial to USB too, works OK except for that renumbering every now and then.
If you are into navigation, steering a boat, way points etc, look into opencpn, and openplotter.
There's nothing in principle to prevent such hot plugging without
damage, but there are some significant practical problems that need
solving in order to give a guarantee in the worst case.
1) As another poster has pointed out, the voltage levels should be
2) The 0V pin must make contact first, followed by the power supply
pin, and the signal pins must not make contact until power has been
established on the other board. It's an unusual connector pair that
would sequence the pins like that.
3) If two outputs are connected together, but they are at opposite
logic states, it's possible that enough current will flow to damage
one or the other pin. Thus, in software terms, you'd want to ensure
that all pins that are going to be connected together have been
configured to appropriate signal directions. If in any doubt,
make the Pi's pins inputs before plugging up.
Alternatively a small resistor (1K will probably do) can be placed
in the lines then even if two connected pins are both outputs for a short
while they won't blow each other up. Lesson learned doing the Torch Z80
board - the data on the ports on both sides said on reset they were inputs,
what it failed to mention was that between power up and reset they might be
outputs for just long enough to break them, resistors solved the problem.
Steve O'Hara-Smith | Directable Mirror Arrays
C:\>WIN | A better way to focus the sun
Electrical theory says it doesn't make any difference if you contact ground
or power first.
The obove can be seen on USB connectors, the power pins (both 0 and 5 volts)
are longer so as to make contact first, but there is no distincion between
both of them.
Most theoretical descriptions only hold as long as the simplifying
assumptions made in their formulation do. Even if your circuit is
totally isolated from anything else it can be any potential whatsoever
and it always has a certain capacity against its surroundings. The
ground plane typically is the most robust part to take the initial
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