DHT22 Wrong temperature readings.

The temperature output dropped to to 1°C when the real temperature got above 26°C.

Steps to reproduce

using var dht = new Dht22(26);
while (true)
 {
         // Try to read the temperature.
         var temp = dht.Temperature;
         if (!dht.IsLastReadSuccessful) continue;

          // Try to read the humidity.
          var humidity = dht.Humidity;
          if (!dht.IsLastReadSuccessful) continue;

          Console.WriteLine($"Temperature: {temp.Celsius:0.0} °C, 'Humidity: {humidity:0.0} %");

          break;
}

Expected behavior

Output: Temperature: 26.0 °C, 'Humidity: 36.1 %

Actual behavior

Output: Temperature: 1.0 °C, 'Humidity: 36.1 %

Versions used

Add following information:

• Dotnet on the build machine: Version: 3.1.1 Commit: a1388f194c
• Dotnet on the raspberry pi 3B: Version: 3.1.1 Commit: a1388f194c
• Version of System.Device.Gpio package: 1.0.0
• Version of Iot.Device.Bindings package: 1.0.0

[Ellerbach]

@fomenkodmitry and @BramEsendam, you are right, there was a mistake. I found some time to dig into the code and found the problem. Line 32 in the Dht222.cs file should be:

var temp = ((readBuff[2] & 0x7F) * 256 + readBuff[3]) * 0.1;

@joperezr, will make a PR asap.

[joperezr]

I’ve merged that PR so hopefully the results will be fine now. I’ll go ahead and close this issue assuming it does, but please feel free to reopen if that is not the case.