2020-06-09 12:08 AM
Hi,
I'm having an problem whereby I believe the temperature readings from an HTS221 device are incorrect. They seems to be around 5degC too high compared to reference temp. I'm using a Nest thermostat as the reference, and while this may not be calibrated I would still expect the temperatures to be roughly similar.
I have suspicion that the calibration registers aren't correct, specifically the T0_OUT value which is zero. Is a value of 0 for T0_OUT expected or is there something wrong with the calibration? Seems a bit suspect to me.
Below is a dump of all the calibration registers:
Calibration Registers
Addr: 0x30 Value: 0x3d
Addr: 0x31 Value: 0x8f
Addr: 0x32 Value: 0x99
Addr: 0x33 Value: 0x0e
Addr: 0x34 Value: 0x00
Addr: 0x35 Value: 0xc4
Addr: 0x36 Value: 0xf2
Addr: 0x37 Value: 0xff
Addr: 0x38 Value: 0x3a
Addr: 0x39 Value: 0x03
Addr: 0x3a Value: 0xf5
Addr: 0x3b Value: 0xd0
Addr: 0x3c Value: 0x00
Addr: 0x3d Value: 0x00
Addr: 0x3e Value: 0x1e
Addr: 0x3f Value: 0x03
So for the linear interpolation of temperature I get the following:
x0 = 0
y0 = 19.125 degC
x1 = 798
y1 = 33.75 degC
However using those values yields temperatures which are too high (by approx 5degC). The humidity also appears to be around 10% lower than the Nest thermostat.
Hardware and Software
I'm using the HTS221 driver from the ST Micro MEMS library. The HTS221 is mounted on a MikroE Click board (https://www.mikroe.com/temp-hum-click) attached to an Azure Sphere dev kit.
At the moment I don't have another HTS221 device to compare with.
Device Configuration:
Data Output Rate: 7Hz
Averaging: H: 512, T:256
Heater: Off
Block Data Update: Enabled
Samples are being read from the device at approx. 1Hz.
Any advice would be appreciated.
Thanks,
Simon
2021-03-05 06:30 AM
Hi Florin,
I understand the point, but unfortunately we don't usually send golden samples except to key customers.
For this reason, I suggested you to contact regional Sales offices and Representatives from this link.
By the way, in general ST MEMS sensors are not indeed 1k$-to10k$ devices equipped with their own dedicated datasheet...
-Eleon
2021-11-24 03:29 AM
hi,
Is there any solution for this issue.
I am using a MKR IoT Carrier with HTS221 sensor. The device is sending a approximately a 5 degree higher readings everytime. I believe this thread is discussing same issue.
Kindly share a fix.
BR,
Ajna
2021-11-26 06:18 AM
Hi Ajna @AShuk.4 , all,
please note that you are using a "third-part" board, and ST cannot guarantee that the performances declared on the datasheet are then met after an unknown soldering process.
Even for STEVAL-MKI141V2 adapter you might be careful.
For this reason, I suggest you to characterize the offset and maybe the gain shift of the parts from the datasheet and "calibrate" them at software leverl, if you need a very accurate application setup.
I also suggest you to collect all your experiences and try asking the question on MKROE forum at this link.
-Eleon