Enviro pHAT pressure

I have two Enviro pHAT (EnviropHAT and EniropHAT2) The ADC male header is soldered on the EnviropHAT.

The EnviropHAT measures negative (!) and too low peressure:

pi@EnviropHAT:~ $ python
Python 2.7.9 (default, Sep 17 2016, 20:26:04)
[GCC 4.9.2] on linux2
Type “help”, “copyright”, “credits” or “license” for more information.

from envirophat import weather
print weather.pressure()
-1999.38893246

EnviropHAT2 measures correct pressusre:
pi@EnviropHAT2:~ $ python
Python 2.7.9 (default, Sep 17 2016, 20:26:04)
[GCC 4.9.2] on linux2
Type “help”, “copyright”, “credits” or “license” for more information.

from envirophat import weather
print weather.pressure()
101146.517167

What is the problem?

Best regards,
Balazs

This is odd- do you get any change in the pressure value if you (gently) press upon the sensor?

I work in a laboratory so I put both Enviro pHAT + zero + power bank trio into a vacuum desiccator https://en.wikipedia.org/wiki/Desiccator) and made vaccum from 101kPa to 90kPa .The Enviro pHAT2 meausred increased pressure, Enviro pHAT pressure change was not significant.

I have noticed that the soldering is not perfect, as shown in the picture.

It could cause the problem?

Best regards,
Balazs

It’s possible that imperfect soldering could be the problem, but unlikely. I suspect somethings gone wrong with the barometer. I’ve seen your support email, and will make sure it’s assigned to someone who can send you a replacement.

Out of curiosity, and the opportunity to add this to my Initial State dashboard, I tried pressure from my Envirophat:.

from envirophat import weather
print weather.pressure()
##  101628.297734

101628…! What on earth?!

Any ideas, please.
Thank you.

In the envirophat guide they use the line:

print(weather.pressure(unit='hPa'))

Which prints out a reasonable hPa value, so I can only presume that the raw value without the unit parameter is pascals, not hectopascals.

1 standard atmosphere is 101,325 pascals, so that’s not exactly unexpected.

I was already using (weather.pressure(unit='hPa'))
But Initial State was showing the wrong figure.

Changed it in IS to "=math.round(convert([Pressure],"pa","hpa"),0)", and all is good.

Thank you.