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I read something about this being typical for all (or many?) VW
vehicles, apparently they don't have dedicated TPMS sensors but
derive the tyre "health" from the ESP sensors.<br>
<br>
If that's correct, there is no way we will ever be able to map the
values to actual temperatures & pressures.<br>
<br>
So… how about adding new relative TPMS metrics & warning/alert
indicators to be used alternatively to the current absolute
temperatures & pressures?<br>
<br>
We could add these now as vectors, and replace the previous single
metrics for temperatures & pressures by vectors as well. That
would reduce the metric payload size on both MQTT and the WebSocket
transport, and also adapt nicely to vehicles with more or less than
four wheels.<br>
<br>
Proposal: numbering scheme rows front to back, left to right per
row. For four wheels:<br>
<br>
<font face="monospace">v.t.pressure fl,fr,rl,rr [kPa]<br>
</font><font face="monospace"><font face="monospace">v.t.temp
fl,fr,rl,rr [°C]<br>
</font></font><font face="monospace"><font face="monospace"><font
face="monospace"><font face="monospace"><font face="monospace"><font
face="monospace">v.t.health fl,fr,rl,rr
[%]<br>
</font></font></font></font></font></font><font
face="monospace"><font face="monospace"><font face="monospace"><font
face="monospace"><font face="monospace"><font
face="monospace"><font face="monospace"><font
face="monospace"><font face="monospace">v.t.alert
fl,fr,rl,rr [0/1/2]<br>
</font></font></font></font></font></font></font></font><br>
</font>The alert vector can use the same scheme as with the battery
cells, i.e. 0 = OK, 1 = warning, 2 = alert.<br>
<br>
The MP message "W" can be replaced by a new one. Proposal: Code "Y",
data:<br>
<ul>
<li>number of wheels</li>
<li>pressure values + staleness</li>
<li>temp values + staleness</li>
<li>health values + staleness</li>
<li>alert values + staleness</li>
</ul>
We can continue producing "W" messages for old clients in the field.<br>
<br>
Anything missing?<br>
<br>
If that's OK for all, I can make the necessary changes.<br>
<br>
Regards,<br>
Michael<br>
<br>
<br>
<div class="moz-cite-prefix">Am 09.01.21 um 19:35 schrieb sharkcow:<br>
</div>
<blockquote type="cite"
cite="mid:9cb4b50f-1d0a-a9a1-c8c5-73dfe5a1f25f@gmx.de">Thanks for
your input, Michael.
<br>
<br>
I agree that we could use the relative metrics to roughly estimate
the
<br>
current assumed pressure from a reference value (which would have
to be
<br>
updated every time a user presses the TPMS reset button...).
<br>
<br>
But: I'm afraid the correlation is not linear, probably not even
<br>
reproducible. Also, we have two pressure-related values per wheel,
while
<br>
OVMS for now has a pressure and a temperature value.
<br>
<br>
So... I think I'd still prefer two relative indicators for the
e-up in
<br>
the app. I can try to work on implementing a custom MP record.
<br>
<br>
sharkcow
<br>
<br>
<br>
Am 08.01.21 um 18:33 schrieb Michael Balzer:
<br>
<blockquote type="cite">Sharkcow,
<br>
<br>
as we don't have a new capabilities message scheme yet,
conditional
<br>
blocks are the way it works right now in the App.
<br>
<br>
The meanings of standard metrics and message data fields should
not be
<br>
changed. Introducing custom metrics and a custom MP record is a
possible
<br>
solution.
<br>
<br>
But having custom solutions for common things like this is a
PITA. Maybe
<br>
we can work something out to convert the readings into the
standard
<br>
metrics?
<br>
<br>
For example: if you get a "health percentage", we could
introduce a
<br>
configuration for the "100%" health pressure level, so we can
get an
<br>
absolute value from that.
<br>
<br>
Regards,
<br>
Michael
<br>
<br>
<br>
Am 08.01.21 um 15:12 schrieb sharkcow:
<br>
<blockquote type="cite">I have now figured out how to read and
partly how to interpret the
<br>
metrics of the indirect TPMS on the e-up.
<br>
<br>
We get a "tyre emergency" and a "pressure diffusion" value for
each
<br>
wheel.
<br>
<br>
Since the values are relative, I would like to transmit them
to the app
<br>
as raw data and only display a percentage (100% means
everything is ok).
<br>
<br>
Would it be ok to just introduce an if-statement in the app to
detect
<br>
whether the vehicle type is an e-up and change the default
displays
<br>
accordingly?
<br>
<br>
sharkcow
<br>
<br>
PS: I feel this value (incl. a useful alert value) would be
very
<br>
beneficial: I just found out that I had lost quite some
pressure over
<br>
the 2 years I own the vehicle without TPMS reacting. The
metrics on OBD
<br>
showed a nicely measureable change however, which could easily
be used
<br>
to have OVMS notify me. (Yes, I should have checked the
pressure
<br>
regularly, but hey: what's a TPMS for?!)
<br>
<br>
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<pre class="moz-signature" cols="72">--
Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
Fon 02333 / 833 5735 * Handy 0176 / 206 989 26</pre>
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