Main Site Documentation

Barometer Problem


#1

Hi All,

I’m reading the barometer values by continuous reading, and I get for around 1 min these wrong values with that simple code :

barometer.MeasurementComplete += new Barometer.MeasurementCompleteEventHandler(barometer_MeasurementComplete);
barometer.StartContinuousMeasurements();

void barometer_MeasurementComplete(Barometer sender, Barometer.SensorData sensorData)
{     
Debug.Print(sensorData.Pressure.ToString());
}


969.6564944988761
1020.7390039164632
1017.1814906725515
1015.3544238650481
880.29095865105205
1009.5142345676992
1089.3395067257059
1012.5939837275509
918.96645676772971
947.61964046222784
1003.0001355528441
981.9533889301631
1026.7166090020464
1056.2537296201256
867.3304217140967
1007.5506305773179
951.66870037659442
1069.5793784188552
791.3127268071994
992.57263117262755
916.98948776457507
1102.4858730243411
959.76884951733007
1069.0551627109414
953.53012201449815
1094.8332017746025
970.33706869094476
1072.8499635112487
1112.1071729687806
1016.4571796358771
923.27809489325227
839.35504186031812
951.62617524652615
1000.0320054049519
1055.7731199771388
987.55323291021523
981.73233253927026
1009.1673538354055
962.14309382203101
1040.2116250737538
985.0179883413366
1099.9760991476205
992.23089152462217
1015.0779513848331
976.77770476209139
1017.2913485391546
1076.4482677839685
880.49340322971784
950.12506201731526
990.3780988689756
989.73660389426436
991.09610525887399
990.59728460238489
869.39135798842176
935.64879983726166
994.78632405708265
1032.5980114474385
919.62146766358728
1215.1873744886261
997.7469142676149
988.59198533560175
1048.725927167151
971.83351658824427
1025.0642961009601
875.1009278037609
1032.0266088733174
980.34249655181588
776.5128984236145
943.71564638601581
1111.1754332772675
1090.433949075393
891.70514906578501
726.88532473388125
1045.4442377162752
1031.2972091072588
983.15466939800558
1142.6506987230935
858.09939131027386

The differences are too big to be correct. Is there something to do to get the right values ?

(I’m working with a Raptor Mainboard)

Thanks !


#2

@ GMISoft. This happens t quite a few of us as well. In fact, I had the same issue as well today. By lightly tapping on the sensor with your fingernail, it seems to resolve the problem. See Reply #3 in post https://www.ghielectronics.com/community/forum/topic?id=14289


#3

@ scardinale : it’s scary… This module is supposed to be Embedded on a drone, with vibrations…
Do you think that tapping on it will definitly résolve the problem, I can live with that. But if we had to do that regularily… It’s for me a serious issue with the hardware…

I’ll try tomorrow and give back the results of m’y tests

Thanks by the way for the workaround !


#4

I’d question whether you’re using the right sensor there. If it’s for interest only, then you’re fine; if you think its fast and accurate enough to help with flight stabilisation, time to look for a new sensor.


#5

@ Brett : I won’t use it for accurate readings, these are clearly not quality built component that I can trust.

But I was expecting more accuracy than that. Difference of 900ft when reading 2 times consecutively, I’m not calling that an “accuracy issue”…
I supposed my barometer component was defect, but I found other peoples having the same problem.

So it sounds it’s a bad component, and I really regret that.

I expected to use it to get an approximate telemetry, and it’s just useless…


#6

I’ve also seen varying readings from this unit. It’s not a reliable unit for sure.


#7

I’m not so sure its the module as I have a couple of them and generally they have worked pretty well for me.

Tonight I put together a Raptor network test, but I thought I’d chuck a couple of barometer modules on it for fun and chart the output from those here on the ‘Raptor Network Test’ tab:

http://open.sen.se/sensemeters/tab/6395/

but in trying to put 2 barometer modules on a single Raptor board it became very apparent that isn’t possible as the temperature/pressure readings were completely wrong for both modules, so careful about multiple I2C data modules.

I’ll leave my test running for awhile and see if I get any whacked out readings.


#8

@ Duke Nukem: You are probably right, I also have a compass, a gyro and an accelerometer on the Raptor.

Do I need to manage their readings to avoid concurrency ? Do I need to split these components on multiple motherboards ?
Is it a bug in the I2C managementof the motherboard ?


#9

@ Duke Nukem - that pressure stability showing on http://open.sen.se/sensemeters/tab/6395/ is really impressive! It is nice to see that the ripple in temperature is not reflected in pressure.
Have you found any vibration or orientation effects with that sensor. On some pressure sensors I have tried, if you change to orientation the reading will change slightly. This is due to gravity acting on the diaphragm, and may be an issue if used on a moving platform. Vibration will also have an impact.
The sen.se website is also quite impressive.


#10

While I’m sure orientation could have some small effect, project boards in my office don’t have that luxury, as I just grabbed a similar project board that I was done with and wired it up for this test and I left it propped up against my laptop for testing, so I really haven’t noticed anything around orientation or vibration, but perhaps something to specifically investigate later.

One of the tests that I’ve meant to do for some time is to test Solder Monkey’s barometer module http://www.soldermonkey.net/shop/index.php?route=product/product&product_id=70 perhaps once I’m done here I’ll fire it up.

The Temperature ripple makes perfect sense here as I’m in Calgary and the outside temperature was like -20 C this morning so the ripples are the furnace kicking on and off and the current decline is the wife trying to freeze me out of my office with the daytime energy saving mode (doesn’t work as I have like number of computers and servers in my office so if I close my door I can get it right toasty in here and the palm trees in my office like that).


#11

@ Duke Nukem : Thx for your tests ! I just order this component of SolderBlog, to check if it could fit my needs.

I’ll try tonight with the other sensors unplugged, I’ll let you know