Hi Geir,
TL;DR: Don't bother.
The one I have was one of a myriad of choices on Amazon,
all doing about the same thing. It's a "Head Up Display
CAR", model A8 HUD. No manufacturer name, other than
"Made in China". I don't actually use it in the car on
a regular basis; I got it for the development and
testing of the obd2ecu code, along with the "SyncUp
Drive" telemetry / HotSpot dongle that I have that
started the whole project.
I've tried using the HUD a few times, but I kind of
don't recommend it. At least, not this one. The
display is too bright to use at night (even though it
adjusts to the ambient), and the semi-reflective plastic
mirror thing that you're supposed to attach to your
window is annoying to use. There's also no place to
really put the whole thing in my Roadster, nor really
the need, given the already-provided car displays. From
the brief survey I did before purchasing the unit, the
HUDs in this category only fetch 4 PIDs - speed, RPM,
coolant temp, and fuel flow (sort of), with the fuel
flow running through a rather opaque transform of Mass
Air Flow that isn't very accurate. I did an
approximation of the inverse in the OBDII engine, to try
to make it somewhat useful, and use it to display SoC.
But it's really crude.
One somewhat trivial difference between units that I saw
was the number of digits in the display of fuel flow.
Mine has 3, many only 2. But the actual result was
disappointing, because in spite of the opportunity, the
unit caps the display at 19.9, vs 99.9, which would have
been useful for SoC. Instead, I have to display SoC/10,
and remember what it means.
The unit also has a bunch of well-meaning-but-useless
alarms, for example, a reminder to shift when the RPM
gets too high. That's set at like 5,000 RPM (on a car
that hits it at typical freeway speeds), and when it
goes off, it's LOUD. Now disabled, along with a few
others. I already have 3 speed indicators in the car
(the analog dash speedometer, the digital display on the
car VDS, and one on the Audio / Nav unit), and none of
them agree with each other. So, I don't really need a
HUD to display a fourth, yet different, value.
So, the HUD is on my desk, where it will stay, next to
the development OVMSv3 proto unit...
The SyncUp dongle is currently in the car, but it keeps
going into sleep mode on its own, for reasons that
appear to be separate from the OBDII interface. Since
that disables the WiFi hotspot, it's also become
effectively useless until I can figure out a way to
trick it into staying awake. I think it isn't sensing
vibration somehow, which is disturbingly spooky. I can
tap it with my finger and it wakes up. What else is it
sensing (and reporting back to the mother ship)?
If you want to get and log other stuff via the OBDII
interface, get one of the Bluetooth or USB OBDII dongles
and a laptop or smartphone with Torque or equivalent
software, and do your display or logging from there. If
it's just one or two parameters to monitor, then the HUD
could be useful if you re-map the 4 requested PIDs to
whatever you want to view. Just recall that the display
is oriented to the original value's purpose (e.g. the
increasing arc for displaying RPM), so your remapping
opportunities are rather limited, and not particularly
usability-friendly.
So far, the best HUD I have found is to get an old
smartphone (sans-SIM), and use it as a wi-fi client to
Michael's excellent Dashboard. THAT is useful for
display while driving.
All that said, what were you thinking of using the HUD
for?
Good luck,
Greg
Geir Øyvind Vælidalo wrote:
I’m thinking about maybe buying a HUD to connect to
OVMS. Do you have any recommendations? Greg, which one
do you have?
Best regards,
Geir
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