[Ovmsdev] indirect TPMS in app

Sun Jan 24 00:13:40 HKT 2021

Michael,

this looks great, thanks!

However, at least for the e-Up we get two values per wheel (diffusion
and tyre emergency). I personally would like to display both in the app.
 From what I understand, I can't easily extend the current metric layout
for that, right?

If this approach is completely unacceptable, I could also try to merge
the two values per wheel into one "health" indicator.

Regards,

sharkcow

Am 17.01.21 um 18:51 schrieb Michael Balzer:
> Everyone,
>
> this is now fully implemented and committed.
>
> Please note I did a slight change regarding the wheel layout and "Y"
> message structure, to better support custom layouts.
>
>   * The TPMS wheel layout now is defined by
>     OvmsVehicle::GetTpmsLayout(), which can be overridden by a vehicle
>     to implement custom layouts. The default is the proposed FL,FR,RL,RR.
>   * The wheel layout is included in the "Y" message as the first part,
>     and the number of values is included for each vector.
>
> See updated MP documentation here:
> https://docs.openvehicles.com/en/latest/protocol_v2/messages.html#car-tpms-message-0x59-y
>
> Example messages from the DEMO vehicle:
>
> Y4,FL,FR,RL,RR,4,206.8,216.5,275.8,175.8,0,4,33.0,33.0,34.0,38.0,0,4,95.0,93.0,96.0,74.0,0,4,0,0,0,1,0
> W31.3982,33,25.4962,38,30,33,40,34,1
>
> I'll take care of supporting "Y" in the Android App.
>
> I've also added an automatic TPMS alert triggered by changes to the
> v.t.alert vector. Example alert text:
>
> TPMS ALERT:
> FR wheel ALERT: Health=91% Pressure=9.1kPa Temp=21C
> RR wheel WARNING: Health=90% Pressure=9kPa Temp=9C
>
>
> No alerts will be set automatically, you need to add setting some proper
> alert level if you'd like to use this new feature.
>
> Regards,
> Michael
>
>
> Am 10.01.21 um 22:40 schrieb Michael Balzer:
>> 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.
>>
>> If that's correct, there is no way we will ever be able to map the
>> values to actual temperatures & pressures.
>>
>> So… how about adding new relative TPMS metrics & warning/alert
>> indicators to be used alternatively to the current absolute
>> temperatures & pressures?
>>
>> 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.
>>
>> Proposal: numbering scheme rows front to back, left to right per row.
>> For four wheels:
>>
>> v.t.pressure            fl,fr,rl,rr [kPa]
>> v.t.temp             fl,fr,rl,rr    [°C]
>> v.t.health         fl,fr,rl,rr    [%]
>> v.t.alert              fl,fr,rl,rr    [0/1/2]
>>
>> The alert vector can use the same scheme as with the battery cells,
>> i.e. 0 = OK, 1 = warning, 2 = alert.
>>
>> The MP message "W" can be replaced by a new one. Proposal: Code "Y", data:
>>
>>   * number of wheels
>>   * pressure values + staleness
>>   * temp values + staleness
>>   * health values + staleness
>>   * alert values + staleness
>>
>> We can continue producing "W" messages for old clients in the field.
>>
>> Anything missing?
>>
>> If that's OK for all, I can make the necessary changes.
>>
>> Regards,
>> Michael
>>
>>
>> Am 09.01.21 um 19:35 schrieb sharkcow:
>>> Thanks for your input, Michael.
>>>
>>> I agree that we could use the relative metrics to roughly estimate the
>>> current assumed pressure from a reference value (which would have to be
>>> updated every time a user presses the TPMS reset button...).
>>>
>>> But: I'm afraid the correlation is not linear, probably not even
>>> reproducible. Also, we have two pressure-related values per wheel, while
>>> OVMS for now has a pressure and a temperature value.
>>>
>>> So... I think I'd still prefer two relative indicators for the e-up in
>>> the app. I can try to work on implementing a custom MP record.
>>>
>>> sharkcow
>>>
>>>
>>> Am 08.01.21 um 18:33 schrieb Michael Balzer:
>>>> Sharkcow,
>>>>
>>>> as we don't have a new capabilities message scheme yet, conditional
>>>> blocks are the way it works right now in the App.
>>>>
>>>> The meanings of standard metrics and message data fields should not be
>>>> changed. Introducing custom metrics and a custom MP record is a
>>>> possible
>>>> solution.
>>>>
>>>> But having custom solutions for common things like this is a PITA.
>>>> Maybe
>>>> we can work something out to convert the readings into the standard
>>>> metrics?
>>>>
>>>> For example: if you get a "health percentage", we could introduce a
>>>> configuration for the "100%" health pressure level, so we can get an
>>>> absolute value from that.
>>>>
>>>> Regards,
>>>> Michael
>>>>
>>>>
>>>> Am 08.01.21 um 15:12 schrieb sharkcow:
>>>>> I have now figured out how to read and partly how to interpret the
>>>>> metrics of the indirect TPMS on the e-up.
>>>>>
>>>>> We get a "tyre emergency" and a "pressure diffusion" value for each
>>>>> wheel.
>>>>>
>>>>> Since the values are relative, I would like to transmit them to the
>>>>> app
>>>>> as raw data and only display a percentage (100% means everything is
>>>>> ok).
>>>>>
>>>>> Would it be ok to just introduce an if-statement in the app to detect
>>>>> whether the vehicle type is an e-up and change the default displays
>>>>> accordingly?
>>>>>
>>>>> sharkcow
>>>>>
>>>>> PS: I feel this value (incl. a useful alert value) would be very
>>>>> beneficial: I just found out that I had lost quite some pressure over
>>>>> the 2 years I own the vehicle without TPMS reacting. The metrics on
>>>>> OBD
>>>>> showed a nicely measureable change however, which could easily be used
>>>>> to have OVMS notify me. (Yes, I should have checked the pressure
>>>>> regularly, but hey: what's a TPMS for?!)
>>>>>
>>>>> _______________________________________________
>>>>> OvmsDev mailing list
>>>>> OvmsDev at lists.openvehicles.com
>>>>> http://lists.openvehicles.com/mailman/listinfo/ovmsdev
>>>>
>>>>
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>>
>> --
>> Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
>> Fon 02333 / 833 5735 * Handy 0176 / 206 989 26
>>
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>> http://lists.openvehicles.com/mailman/listinfo/ovmsdev
>
> --
> Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
> Fon 02333 / 833 5735 * Handy 0176 / 206 989 26
>
>
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