[moolight0551]

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I am getting good data from the AQM on the Pro2 Plus except for the AQM Temperature and Humidity which is always 9945 and 9980 on the Web page and I suspect this messes up the Dust Density calculations. The reason I say this is that I notice in your code if you select #define TH_SENSOR    0 then the AQM sends 25 deg C and 50% RH and then I get some meaningful Dust Density figures on the Pro2 Plus display.
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Hi,

You are right about that. The data from the Temp / hum sensor are used on the calculations, so if data is wrong the results will be wrong too.

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I have some SHT21 sensors on order and will try them when they turn up, but in the meantime any suggestions to problem solve would be very welcome.
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Please not that the SHT21 isn't supported. The best choice for the AQM II is the SHT31, 3,3V version.

My bad typing, I have bought SHT31 sensors supposedly 3.3V types. Will wait for delivery and test.
 

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I have tried 2 different HTU21D sensors and each one gives the same readings. I have tested both of these on an Arduino with a test sketch and they both report readings similar to the Pro2plus sensor so believe they are OK.
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Could it be that your HTU21D sensors are the 5V version and don't work reliably with 3.3V?
This ones are 5V version



When you tested it on Arduino, you used the same library used by the AQM II? If yes, then they are on the expect I2C address, which is 0x40.

No I did not, used an Adafruit library I think. Will try the same library as in the upload. Will also check the address. Thanks

Another possibility... the pinout for the T/H sensor on the AQM II board is for the SHT31, most HTU21D modules, specially the 3.3V versions, have the SDA / SCL lines reversed, so they can't be fitted directly on the PCB. Check this too.

I used the Arduinos 3.3V supply for my test and also checked the SDA/SCL reversal as I have one like that that I bought without looking at the pinout.

At moment I don't have any HTU21D to test. My best suggestion is to install an SHT31, they are far better than the HTU21D and more durable, specially under heavy moisture environments.

By the way, your Config_Options seems fine to me.

Good

Hope I have helped.

Rgs.
Werk_AG

Thanks for your suggestions, see my comments in italics above.

Regards Dave