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Forum Index : Microcontroller and PC projects : having some issues with BME280

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MikeO
Senior Member

Joined: 11/09/2011
Location: Australia
Posts: 275
Posted: 02:27am 28 Apr 2018
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Hello , I decided to try a BME280 (adafruit module) in place of the DHT22 I was using in my weather station to try an mitigate the DHT22 desire to saturate very easily for humidity. I had read that this was the way to go BUT unfortunately I find that the temp is reading some 5-6 degrees plus high?
I am using matherp's (all basic) library . I wonder if this is something others have experienced? I do see when I do a search that there are references to this happening but this is with Arduino libraries and seams to be related to initial readings. Mine is always reading high. I have decided now to also install a new DHT22 and run them both for comparison.

I have tried 4.7K pullups on the lines, I doubt it a self heating problem , its standing off the board in free air .

Any thoughts
Codenquilts
 
MikeO
Senior Member

Joined: 11/09/2011
Location: Australia
Posts: 275
Posted: 05:02am 28 Apr 2018
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Update:

Oh dear I have opened a can of worms for my self, It seems the temps are within 1-2 degrees of each other (BME280 and DHT22).

I have now used my commercial thermocouple temp meter and the DHT22 is the nearest to ambient , about 1 degree high and the BME280 2.5-3 degrees high.
The problem is I was trying to to to a new enclosure with the sensors in with the electronics but mounted off the board but it seems the air temp in there is probably a degree or so warmer than the actual outside air temp.

The conclusions are it does appear that the DHT22 for temperature at least is more accurate than the BME280. The Humidity of the BME280 is nearer what i believe to be
the actual humidity but low and the DHT22 is high. The pressure is way out.
Codenquilts
 
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