Nicla Sense ME temperature and humidity inaccurate

Other Hardware Sensors
1

I have three Nicla Sense ME boards, and on all of them the temperature is about 7.5 degrees too high, and the Humidity is about 22% too low. As well as being a hopeless temperature and humidity sensor, I understand this will also invalidate the gas sensor readings.

I have had a topic open on the Bosch Sensor forum for several weeks, and been in contact with Arduino Support for a couple of weeks without resolution.

I'm interested to know whether anyone doesn't have this problem? If not, what is the USB serial number of your device. This can be found with:
ioreg -p IOUSB -l -b | grep -E "@|PortNum|USB Serial Number"

2

A tiny board, packed with sensors and a BT radio.
And you're wondering why there is some temperature increase?
This is not the only board with this behaviour.
Did you try a fan to blow suck air away from the board.
Leo..

3

I'm not so much wondering why there's a temperature increase, as wondering why a $70 'Pro' sensor board would be designed to include environmental sensors that don't operate as specified. It's essentially a really expensive bluetooth accelerometer as far as I'm concerned.

I haven't tried a fan, I was waiting to get some response from Arduino or Bosch confirming the source of the problem.

Is there some way to disable the bluetooth module?

4

Hey there,
I have performed some "calibration myself".
I have taken readings from different sensors:

Readings
Readings1805×316 141 KB

Notes:

  • Every row in the table is a different location
  • Every reading is the average of the last 5 readings, after 3 minutes of running to have the value settle.
  • The Smart Air (which is boasting 99% accuracy and is about $120, has been left to run for 15 minutes to settle.
  • For the pressure I used an Airport Weather Station that is close to me.

And then used Linear Regression to calibrate it to the accurate values (which is the Smart Air Monitor):
Temperature:

temp_nicla
temp_nicla4689×3705 469 KB

Humidity:
hum_nicla
hum_nicla4691×3703 445 KB

The pressure only needs a 0.7% flat increase.

So the final formulas to have your output correct are:

  • correct_temp = 1.0095 * nicla_temp - 4.8051
  • correct_hum = 1.4383 * nicla_hum -2.5628
  • correct_pressure = 0.718/100 * nicla_pressure + nicla_pressure

Furthermore, the Air Montior rounds up temperature within the next .5, and the both the humidity and VOC are rounded to the next integer. So those values were used for Linear Regression.
Mind the fact that the IAQ is calculated differently on the Air Monitor by using the Particulate Matter and Carbon Monoxide, with different weights. The Nicla calculates it with temp, hum, voc, estimated co2(not actual).

5

Hi, any official statement from Arduino or Bosch?

6

$70? Oh my, it`s a Pro price, too :smiley: