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Arduino nano 33 BLE pressure sensor strange data
#1
Photo 
I  try to use the Arduino nano 33 BLE sense controller with the experiments from physics reimagined
The pressure sensor has a  strange behaviour. Every few seconds the pressure value sinks momentarily and returns to the original value.
Does any one understand the cause of this?
[Image: Screenshot-2021-06-21-19-21-24-027-de-rw...hyphox.jpg]
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#2
Have you tried the experiment USB-powered? A first (rather uneducated) guess would be current supply issue…
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#3
(06-22-2021, 04:12 PM)Jens Noritzsch Wrote: Have you tried the experiment USB-powered? A first (rather uneducated) guess would be current supply issue…

The result is  exactly the same !
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#4
Hey,

I just checked the pressure experiment with my arduino sense. Unfortunately I cannot reproduce this issue. Right now it looks like your sensor is not working correctly or you living in an interesting area..
Could you check how much the pressure difference is?

Cheers
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#5
The repeating pattern is this: every about 9,5s the pressure drops for about 1,5s . The greatest difference is 0.2Kpa.


You can see the data taken at the attached xlsx file


Attached Files
.xlsx   phyphox 2021-06-23 18-16-59 (1).xlsx (Size: 37.85 KB / Downloads: 47)
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#6
Hello,

I have also seen similar feature on some of my Arduino 33 BLE sense. The amplitude of the effect is different on different boards, but i couldn't determine the origin of this feature. I ended up ignoring them...

If someone can make sense of it, I would be interested too.

Cheers,

Fred
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#7
Hello,

I have tried the program mentioned above and also observed some kind of regular peaks (Pressure pulses 2021-08-30 20-50-27.png) that I have never seen before. I have only modified the phyphox code (pressure_plot_v1a.phyphox) for the pressure acquisition in order to see better the peak heights.

So, I have verified pressure recording using my own programs (bar_arduino_nano_fast.zip; bar_arduino_nano2.phyphox) and have not seen such peaks (Pressure from Arduino 2021-08-30 21-00-35.png).

Pressure variations observed are real as can be seen using two different pressure sensors

Here is the code for two sensors (bar_Arduino_SensorTag.phyphox) and the corresponding result (Pressure from Arduino and SensorTag 2021-08-30 21-03-11.png).


Attached Files Thumbnail(s)
           

.phyphox   bar_Arduino_SensorTag.phyphox (Size: 4.73 KB / Downloads: 23)
.phyphox   pressure_plot_v1a.phyphox (Size: 3.69 KB / Downloads: 22)
.zip   bar_arduino_nano_fast.zip (Size: 950 bytes / Downloads: 16)
.phyphox   bar_arduino_nano2.phyphox (Size: 1.98 KB / Downloads: 19)
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#8
Hello Solid,

Thank you for your tests. I am a bit lost however, I think I did not clearly understand what you did, sorry.

If I understand correctly, you measured the pressure using the same arduino nano 33 BLE, but with different programs, and when you used your own programs you couldn't see the dips anymore, did I get it right? If yes, it seems to me that it indicate a software problem, and yet you conclude that the pressure variations are real. Just to be clear: I am focusing on the clear and sudden drop of pressure, such as seen in your middle attached file, but that I do not see on your last attached file with both the Sensor tag pressure data and the ARduino (nano 33 BLE ?) data.

I will have to look at your program to understand how large are the differences...

Cheers,

Fred
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#9
Hello Fred,

I played a little more with the original program. When you change parameter "period" the peaks change..

Best
Mikhail
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#10
(08-31-2021, 11:08 AM)solid Wrote: Hello Fred,

I played a little more with the original program. When you change parameter "period" the peaks change..

Best
Mikhail

Hello,

OK, so that clearly points toward either a software problem, possibly link to an hardware communication issue with the pressure sensor on the Arduino Board.

[...]

OK, I found the following discussion, which addresses the same issue I think:

https://forum.arduino.cc/t/strange-readi.../632520/12

I do not have a nano board on hand just now to play with it, but I will soon.

Cheers,

Fred
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