Bug Filed on 07-25-2016: BMP180 did´t use altitude


#1

What dashboard are you using? (Web, iOS, Android)
Web, Android


What OS? (Jessie, Wheezy)
Jessie


What Model Pi?
RPi 2


Please describe the bug / issue. Attaching any relevant screenshots would be very helpful!

Hello,
i have an BMP180 installed on my Pi.
The sensor works perfect and i get data on my cayenne dashboard!

Now where is the Probleme?

My Altitude is 335m above sealevel, and i placed my altitude in the mask of the sensor.
But i have no change of my data in the dashboard.
Also doing reboot and complete stopping any service.

At the moment my Pressure is 97650 which is 976.50hPa (can you fix the /10 factor?) on a normal, cloudy day. if i use any webservice or my formula for pressure/altitude i get 1014.05hPa which is the right pressure for my altitude!

I tested two sensors with two different Pi.
Every time the same “probleme”

Thank you and greetings from Germany


#2

Chris,

Welcome to the Cayenne Community!

A question on your problem. You didn’t mention if you were using the corrected sea level pressure in any of your altitude calculations. To get an accurate altitude measurement with a pressure device you must know what the pressure would be at sea level.
Read the section on Use as an Altimeter here-

I do have some more thoughts, but I need to go to work.

Looking forward to your response from the home of my ancestors.
Again, welcome,

Ian


#3

Hello Ian,

thand you for your answer.
But i think we talk about different problems.

My sensor is not calibrated with any levels/temperature.

In my mask from the widget i could set my level of altitude, but why?
If i set 0 oder 9000m, nothing take any effect on the widget.

The widget shows every time the same value.

I think only problem is the value fixed to my level above the sea. Then the value is right to any other weather stations near to me.

my value + the difference to sea level = right preasure to any other station near my station.

ok, if you want real precise values, the temperature takes also effect.
but this is real good enought for my home weather station.


#4

@chris2 @Ian Looks like we made progress and got this figured out. Good work guys!

Moving this to the Resolved category, hope you don’t mind.

-B


#5

@bestes, Has this been resolved? I got a BMP180 and entered 130 as my altitude in meters above sea level. I was expecting the output to increase by ~1530Pa for that altitude which would be very close to the current live meteorological data on atmospheric pressure at sea level but the output value did not change. Even if I simulated the RPi ontop of Mount Everest ~9000mt, no change.

Regards,
BAZ


#6

@baz

I came across this thread looking for answers on the same behavior, and I contend its a bug in our Add Device process. In my opinion either editing this value should do something to the readout on the widget, or we shouldn’t prompt you to fill it out at all (what is the point if we’re not using the altitude number entered).

I’ll investigate with our development team, but moving this issue out of the Resolved category for now since it appears to be still an issue.