Issue with Jeti and MPXV7002 and ADS1115

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Yogilours
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Issue with Jeti and MPXV7002 and ADS1115

Post by Yogilours »

Hello ,

Firts thank you for this exceptionnal project !I managed to display on my Jeti DS16 the variometer, the temp and the altitude (with MS5611, IMU6050) but I have a problem with the airspeed. I have a ADS1115 and a MPXV7002 that I configured (I hope) like in the description file.

My problem is that I have a measure only If I use in the basic option:
#define AIRSPEED_SENSOR_USE MS4525 // select between NO_AIRSPEED , MS4525 , MPXV7002

If I use
#define AIRSPEED_SENSOR_USE MPXV7002 // select between NO_AIRSPEED , MS4525 , MPXV7002

I have no telemetry available.

Please tell where I did fail ! I attached the Config files with the message.

Thanks a lot

Guillaume
oXs_config_basic.h
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oXs_config_advanced.h
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mstrens
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Re: Issue with Jeti and MPXV7002 and ADS1115

Post by mstrens »

I just check the code and I saw that this option (airspeed based on MXPV7002) has not been added in the code.
I will try to add it in the comming days.
Yogilours
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Re: Issue with Jeti and MPXV7002 and ADS1115

Post by Yogilours »

Thanks a lot ! Just to be curious where will it be implemented ? In .h file ?

Guillaume
mstrens
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Re: Issue with Jeti and MPXV7002 and ADS1115

Post by mstrens »

it has to added in oxs_out_jeti.cpp
mstrens
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Re: Issue with Jeti and MPXV7002 and ADS1115

Post by mstrens »

I put on github a new version in order to get airspeed using ads1115 for jeti protocol.
I did not tested it.
Let me know if it works.

Yogilours
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Re: Issue with Jeti and MPXV7002 and ADS1115

Post by Yogilours »

Hello,

I just tested it it works perfectly ! Thanks a lot for the fast reaction ! I just don't have 0 km/h when not using it but I think it's somewhere in the parameters.

Thank you again !
mstrens
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Re: Issue with Jeti and MPXV7002 and ADS1115

Post by mstrens »

Not having 0 should not be related to a parameter because, in principe, oXs does automatically a calibration at poweron in order to get 0.

What value do you get?
Is the value stable (when there is no airspeed)?
Did you try adding an RC filter on differential pressure signal to reduce noise (a member said on this forum that such an RC filter was useful) ?
Yogilours
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Re: Issue with Jeti and MPXV7002 and ADS1115

Post by Yogilours »

Hello,

I have around -10km/h. It starts at 0 and drifts to -10 in about 15seconds and is quite stable.

I tried with and without the filter (I hope I plug it well...) and I also tried to change the offset of the Vcc/2 on A1 with a 3 pins 20KOhm potentiometer instead of the 2 10KOhm resistors.

So with the potentiometer I can achieve 0km/h (nearly) but if I reset the system without touching the potentiometer it drifts again.

Maybe is it an internal problem with the airspeed sensor ? Maybe should I use the Lua scripts to be able to reset airspeed from the radio ?
mstrens
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Re: Issue with Jeti and MPXV7002 and ADS1115

Post by mstrens »

It could be that or the differential pressure sensor or the ads1115 has some drift with the increase of the temperature at startup.

oXs allows to make a reset of the airspeed using a PPM signal (in fact the right name would be a PWM = the signal sent to a servo) from the Rx.
Did you test this option?

An alternative could be to change the code in order to add some delay at startup and so taking the voltage after 15 sec as reference for the zero of airspeed.
Yogilours
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Re: Issue with Jeti and MPXV7002 and ADS1115

Post by Yogilours »

Hello,

I'll try this evening the reset from the radio (if I understand well a simple switch with +100/-100% travel is enough), I'll also try to change the entries of the ADS1115. I'll also see if I declare a MS4525 if it's better. It will probably give wrong values but I'll see if there is a drift.

Guillaume
Carbo
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Re: Issue with Jeti and MPXV7002 and ADS1115

Post by Carbo »

I never noticed the drift, because i reset Alt and Airspeed habitual before every flight with PPM/SPort command. But there is a drift, as you can see in the log. It is 5.6 kts here, equals 10.37 km/h. Do you think, what i think :) ?
warmup.png
The RC filter is only needed for dte vario, because the vario is a little bit noisier than i am used to from MS4525. With filter it is equal. You can see the noise/ripple here: viewtopic.php?f=86&t=10000#p125596

Edit: Forgot to add, that the log above was made with a 100kΩ 1µF RC filter, therefore no ripple visible. The airspeed delay is not noticeable for me, calculated tau-time is 100msec.
Last edited by Carbo on Sat Nov 25, 2017 6:29 am, edited 1 time in total.
Yogilours
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Re: Issue with Jeti and MPXV7002 and ADS1115

Post by Yogilours »

Hello,

I read your thread many times... and I confirm that if I reset the speed from the radio there is no more drift. Si I you think that I think what you think we probably think the same :D !

Could you please tell me what is dte vario ? I see that everywhere but I still don't know what it is.

I will also try the MS4525 I found it at the price of the MPXV7002 at www.components-center.com/‎

Thanks !

Guillaume
Carbo
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Re: Issue with Jeti and MPXV7002 and ADS1115

Post by Carbo »

Yogilours wrote: Fri Nov 24, 2017 7:32 pmCould you please tell me what is dte vario ? I see that everywhere but I still don't know what it is.
A usual vario signals vertical speed, a "delta total energy" vario considers also changes in horizontal speed. https://en.wikipedia.org/wiki/Variometer

@mstrens: do you think an offset +10km/h only for coldstart is possible? Or will it affect also airspeed reset?
Last edited by Carbo on Sat Nov 25, 2017 11:35 am, edited 1 time in total.
Yogilours
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Re: Issue with Jeti and MPXV7002 and ADS1115

Post by Yogilours »

Hello,

Tahnks for this answer I will read that !

Guillaume
mstrens
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Re: Issue with Jeti and MPXV7002 and ADS1115

Post by mstrens »

Carbo wrote: Fri Nov 24, 2017 9:01 pm
@mstrens: do you think an offset +10km/h only for coldstart is possible? Or will it affect also airspeed reset?
It depends on the way it is coded.
It would be possible to add the offset only when oXs startup and not in case of airspeed reset.
Still, this would not help in all cases if it is temperature related.
E.g. if you power off and power on oXs immediatedly.
It could be that the offset to be used depends on the external temperature.
Carbo
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Re: Issue with Jeti and MPXV7002 and ADS1115

Post by Carbo »

Or a 30s countdown, if a MPXV7002 is configured, transmitting the seconds as airspeed data. Would be a cool feature in my pov 8-)
Yogilours
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Re: Issue with Jeti and MPXV7002 and ADS1115

Post by Yogilours »

Hello !

I finally got my 4525DO-DS5AI001DP ! Everything seems good. No drift...

Guillaume

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