BMP180 Pressure widget problems

Connected this up OK and works with correct temperature and pressure in pascals at least initially. However change the unit on the pressure widget and it falls away to nothing and you can’t get it back unless I remove the device and start again. Also the height seems to make no difference to the pressure reading - surely this should correct to a sea level reading?
I2C address correct and device works faultlessly on a locally connected arduino.

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Hey @ecarter1024, welcome to the Cayenne Community and thank you for posting.

I think you might be onto a legit bug with our Arduino BMP widget here since I’ve set this up and see the same initial value, but then nothing after toggling the ‘units’ dropdown. I’m going to investigate a bit with our dev team tomorrow and get back to you, thank you for your patience.

Hi Community!

I have the same problem. Use PI2 and pressure sensor BMP180. The widget on the phone (Moto E) show pressure but always in pascals. On the computer with Chrome or Mozilla, appears blank. Attach screenshot:

I used a simple python script to test the sensor.

BMP180 is OK :slight_smile:

I am available to collaborate in what I can.
Thank you very much!


Thanks Sebastián,

I added a link to your post into our internal bug tracker for this issue so development has someone to contact if they need to see the issue first hand. I don’t think they will, since we can reproduce this internally as well.

Can I ask if you and change the pressure units value on the Android phone widget OK, without losing your reading?

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Hi Rsiegel
I had different problems on the android app in that I don’t think I could
change the units. Also no entry for height (not that I think that is making
any difference)
Cheers Eric

Hi Eric,

I can confirm the missing Units dropdown on the BMP180 widget on Android. Definitely a bug/oversight on our part and something I’ll get logged for a fix. What do you mean by height in this context?

Hi Rsiegel
The widget asks for the height which is reasonable because met office
barometric readings are referred to sea level. Hence a reading at say 100
metres above sea level would read less than if it was made at sea level
under the same weather conditions. Hence the met office refer all their
readings to sea level. The correction I believe requires the measured
reading, the height above sea level in metres and the temperature in
degrees kelvin and is applied using the formula
sea level reading = measured station reading in mBar (hetropascal) / e^
-(height /(temperature * 29.263)) where (e^ is exp ‘e’ to the power of)
Hope that helps
Cheers Eric

It does help Eric, thank you. I know that we don’t offer a field for altitude when adding the BMP180 to an Arduino (and we do when adding to a Pi.) It appears consistent across all platforms, web and mobile. I’m looking into confirming whether this is an oversight, or if the expectation is you would just make the correction in your sketch code for Arduino.

Hi rsiegel!

No, I can not change the unit, the option does not appear. Always in Pascals. If I try to modify any other parameter, no reading is lost at any time. I must say that for the temperature, also does not appear the option to change unit.

Thank you!!!

If I try to modify any other parameter, no reading is lost at any time. I must say that for the temperature, also does not appear the option to change unit.

For this part, is it Android, web, or both? I don’t see this issue with my Raspberry Pi / BMP 180. Could you take a screenshot of the settings screen for the BMP 180 temp widget with no Temperature units available to change?

Dear rsiegel: attach the screenshot from the Android.


Modifying units is only possible from the web. From the phone can change
type of widget, name, altitude. Note: Changing the barometer widget name
changes the name of the thermometer widget. The thermometer widget asks to
enter altitude.

Dear rsiegel:

Update, last test!!

I repeat the same test with an Arduino Mega + Shield Ethernet W5100 + BMP085 and exactly the same thing happens. I can only make modifications from the web browser. When trying to pass from Pascal to hectopascal, the values ​​disappear. With the temperature units there are no problems. From Android the value of the pressure is still showing normally, but in no case it is possible to display it in hpa.
I hope it serves as a reference.

Yes - I confirm that is the case for me

@ecarter1024 @sebamardamiano Hey guys,

We recently pushed a fix for this issue on the web side of dashboard for breaking the BMP180 pressure widget. Please let us know if it is not fixed!



Thanks! Then i Will do the test with Arduino and PI!

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Sounds good!


Hi guys!!!

Test from the phone: the thermometer widget shows the unit of degrees kelvin. Conversion OK. The barometer widget displays values ​​in pascals. Can not change drive.

From the navigator: the thermometer allows to make all the changes. Meanwhile, with the barometer the problem continues. It stops displaying values ​​if you try to change to hectopascals.

It is necessary to reinstall the sensor to see the pressure again.

With Arduino Mega + Shield Ethernet W5100 the same thing happens.

Hi Benny
Sorry but seems to be the same in that once you try and select units
-either pascal or hetropascal - you get no reading at all and can only get
it back by removal and re-install
Set up is and RPI2 but as I recall it was the same on an RPI3 and viewed on
Chrome browser through Ubuntu 16.04 desktop. Same issue on Firefox. Android
can’t change units anyway
Cheers Eric

Any fix for this? I have the same issue with the BMP180 and hPa.