Bangle.js2 - incorrect pressure readings

[espruino-discuss2]

Posted at 2022-06-14 by jacek_o

Hi,
I bought SMAQ3 directly from Alibaba. I built espruino version: 2v14 and now I'm trying to read pressure.
First impression was like I get correct values but when I keep watch in hand, pressure increases along with temperature. I have seen that pressure correction is calculated inside the source code. I have tested it as well with ZephyrOS + BME/BMP280 driver and I got similar result. My recent idea is, that I received device with tightly-closed sensor without contact with environment.

Did anybody struggle with this problem?

Best regards,
Jacek

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Attachments:

• banglejs2_pressure.png

[espruino-discuss2]

Posted at 2022-06-15 by @fanoush

My recent idea is, that I received device with tightly-closed sensor without contact with environment.

Yes, that is most probably the problem. They later added small hole on the top side where the strap is. If you have no hole there the watch is a bit more waterproof but you get pressure inside watch not outside. Also search the forum here, there are more details, some early Bangle 2 watches are like that too. I also have such Q3 without hole and can confirm it behaves like that.

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Posted at 2022-06-15 by jacek_o

I haven't noticed any hole. I will drill small one :)
Thank you!

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Posted at 2022-06-15 by @fanoush

found the topic - check http://forum.espruino.com/conversations/370717/#16299790 or here http://forum.espruino.com/conversations/374715/#16475478

regarding the hole - there is some stuff in it to protect from dust/water but keep pressure sensor working, also I can't find some photos of internals now but let's hope you won't break something inside near the hole you make

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Posted at 2022-06-15 by @gfwilliams

some early Bangle 2 watches are like that too

The developer editions had a hole, but no membrane - but I don't believe any of the watches I sent out had no hole (only the early ones I used for development here).

But yes, there's the aerial right along the top. Honestly, I'd say a hole in the bottom might be more sensible if you're doing it after assembly :)

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Posted at 2022-06-17 by jacek_o

So I have got "early ones" from Alibaba. Out of curiosity, I burnt out hole in the up-right corner using needle and now I have correct readings (METAR - elevation for comparison) :)
Thanks for your help!