Closed SunboX closed 6 years ago
Btw. I've been comparing results from DHT22 and BME280, and the BME280 is definitely better with humidity measurements.
On 20 June 2018 at 11:13, André Fiedler notifications@github.com wrote:
I want to use the DHT22 because I read it has the best accuracy.
For air pressure measurement I want to use the BMP180. But this one also has temperature measurement build in.
So if I use both together, which one will "win" in case of reporting temperature?
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I guess, luftdaten.info will use the DHT22 temperature measurement. Because I read, that I have to tell that I'm also using the BMP180 so it will be manually added to the database. I guess this manually adding step makes sure, that the DHT22 temperature will be used?
PS: I also own a BME280... so if someone tells me, that it also works fine. I maybe use this one instead of the other both. Saves costs (for future sensors) and also saves some wiring.
Thanks for the notes André.
I'm looking at the sensor data ( I'm sort of a data analytics person ) and will do a comparison between the BME280 and DHT22 for humidity data, one of these days…
Bests / m
On 21 June 2018 at 09:00, André Fiedler notifications@github.com wrote:
I guess, luftdaten.info will use the DHT22 temperature measurement. Because I read, that I have to tell that I'm also using the BMP180 so it will be manually added to the database. I guess this manually adding step makes sure, that the DHT22 temperature will be used?
PS: I also own a BME280... so if someone tells me, that it also works fine. I maybe use this one instead of the other both. Saves costs (for future sensors) and also saves some wiring.
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For the published data: all sensor data from registered sensors is published. So if both the DHT22 and the BMP180 are registered the temperature of both will be published. Graphs at Madavi.de: graphs are created for all sensors. Maps: there its a matter of implementation. Most maps (if the show temperature and humidity values) will prefer the temperature of the BMP180. But the may also show both. Sensor internal webserver: shows all values Displays (OLED, LCD) connected to the sensor: the order of preference for displayed values is DHT22 DS18B20 -> HTU21D -> BMP180 -> BMP280 ->BME280. So in your case the temperature values of the BMP180 is shown on the display.
I read, that the temperature differs by 2°C between those both and that the DHT22 reports the more correct temperature.
Do you also have some time to look into this?
@SunboX How are they positioned? The temperature sensors should be placed as near as possible to one of the openings.
I did not investigate both temperatures. It's just what I've read somewhere. My electronics is working, but I have to put everything together now. Maybe today. Thanks for tge hint with the positioning!
The slightly higher temperature was for the BME280 (temp., humidity, pressure). The Arduino library for this sensor sets a continuous operation mode as default. And this leads to the higher temperature. We have changed the mode so that the BME280 is only active when needed.
Ok, I installed it now at it's final destination (with DHT22 and BMP180). Both sensors are close to each other and close to the opening of the airRohr:
https://opensensemap.org/explore/5b28d3891fef04001bd7dfae
The temperature values are slightly different. But it's ok for me, thanks for your help @ricki-z & @miskaknapek !
@miskaknapek I'm really interested in your evaluation. Can you give me a hint please when you are done? (andre.fiedler@me.com)
I want to use the DHT22 because I read it has the best accuracy.
For air pressure measurement I want to use the BMP180. But this one also has temperature measurement build in.
So if I use both together, which one will "win" in case of reporting temperature?