Attila,
Has this board been restarted lately? Does the temperature error exist
after a reboot of the hardware/software?
One very long shot/minor concern is errors in the calculation in the
micro due to bit flips or other silliness with the calibration
coefficients in the micro controller memory. (This would only be a
concern for devices where the coefficients are only read at startup).
Is it possible there is actually more heat near the sensor? New
computer/phone charger, or failing power supply near by?
I'm also curious how much these drift, as I've been running them in the
lab here too.
Dan
On 11/29/2022 10:22 AM, time-nuts-request@lists.febo.com wrote:
Moin,
I have been monitoring my lab with a homebrew sensor board based on a BME280
combined temp/hum/pressure sensor from Bosch. Unfortunately, the sensor seems
to have quite some drift. Now, 4 years later, one of them shows 30°C when
every other thermometer in the room shows ~22°C. And as temperature is
needed to for compensation of the other measurements, I can't trust those
either.
So, now I'm about to design and build a new system that has better long
terms stability.
At the moment I think I will go with separate sensors for temp, humidity
and pressure. Temperature is "easy", a PT100 will do the job nicely.
For humidity, there is the SHT line from Sensirion that is well known.
But I don't know of any decent absolute pressure sensor that is long-term
stable and doesn't cost an arm and a leg.
Does someone know a pressure sensor that is long-term stable?
Attila,
Has this board been restarted lately? Does the temperature error exist
after a reboot of the hardware/software?
One very long shot/minor concern is errors in the calculation in the
micro due to bit flips or other silliness with the calibration
coefficients in the micro controller memory. (This would only be a
concern for devices where the coefficients are only read at startup).
Is it possible there is actually more heat near the sensor? New
computer/phone charger, or failing power supply near by?
I'm also curious how much these drift, as I've been running them in the
lab here too.
Dan
On 11/29/2022 10:22 AM, time-nuts-request@lists.febo.com wrote:
> Moin,
>
> I have been monitoring my lab with a homebrew sensor board based on a BME280
> combined temp/hum/pressure sensor from Bosch. Unfortunately, the sensor seems
> to have quite some drift. Now, 4 years later, one of them shows 30°C when
> every other thermometer in the room shows ~22°C. And as temperature is
> needed to for compensation of the other measurements, I can't trust those
> either.
>
> So, now I'm about to design and build a new system that has better long
> terms stability.
>
> At the moment I think I will go with separate sensors for temp, humidity
> and pressure. Temperature is "easy", a PT100 will do the job nicely.
> For humidity, there is the SHT line from Sensirion that is well known.
> But I don't know of any decent absolute pressure sensor that is long-term
> stable and doesn't cost an arm and a leg.
>
> Does someone know a pressure sensor that is long-term stable?
