pysense: lots of invalid temp/hum values

[syncope]

@bucknall said in pysense: lots of invalid temp/hum values:

This is expected as the temp sensor on the pysense is picking up the temperature of lopy as well. We're working on using the LoPy's internal temp sensor to use as an offset for pysense to give you the real world external temperature (One of the issues with having such a small PCB + package!).

do you have any news about the offset?

[bucknall]

@chumelnicu This is on the roadmap but unfortunately I can't give you an estimate of when it will arrive as we have a number of important firmware features/changes that are taking priority.

Thanks for your patience!

[bucknall]

@syncope Unfortunately not yet, we're still to implement the internal temperature sensor from Espressif so are waiting to implement that code before releasing a library for the offset!

Thanks for your patience,

Alex

[chumelnicu]

@bucknall Thank you !!! Just let me know when is ready ...i'm pretty sure a lot of people will apreciate mbus library :)

[bmarkus]

Testing pysense with LoPy 1.7.9.b3 and pysense 1.1.0. No invalid values, the only issue found temperature returned by SI7006A20 and MPL3005A2 has 1.1 Celsius difference. Do not know which one is correct, need a measurement with another sensor.

[GrtVHecke]

@albert_c, @bucknall in pysense: lots of invalid temp/hum values:
Is there a library now available that gets the correct temperature of the pysense board (taking into account the offset)? This question since the topic seems to have died without any answer and it is important for me to know. So I know I can purchase the pysense or not.

[Martinnn]

@grtvhecke
Which offset are you referring to? I currently get 29 °C out ot the SI7006A20 at room temperature.
Obviously the WiPy gets quite warm and heats up the whole assembly, SI7006A20 measures the PCB temperature (which is probably correct, I did not verify this). So it is pretty much useless for measuring ambient air temperature.
The only way to fix this (as I see it) would be a remote (thermally isolated) temperature sensor - or running the WiPy (or whatever board you are using) in a low power mode generating a negligable amount of heat.

[GrtVHecke]

@martinnn So what you are basically saying is that the pysense board can not be used for temperature monitoring. Which is a shame since I thought this was the purpose of the board. I saw other messages mentioning pycom would integrate offsets depending on the processor temperature to compensate this (or I misunderstood). That is what I was asking for.

[catalin]

hi @GrtVHecke, there are other forum threads debating this problem.

It can be quickly mitigated by compensating yourself, it's a linear simple compensation(t_ambient = a * t_pysense + b), so you need to measure temperature in 2 cases (desk/office and outside/fridge) to find a and b.

These measurements should be made in the normal conditions (battery, sleep regime, active radio connections).

[GrtVHecke]

@catalin Thank you for the response. Can you please provide the link to the forum thread debating this?