Trying to use only DHT22/AM2302 Sensor Data for Indoor Reporting

[tho...@gmail.com]

Greetings,

I'm trying to make a small indoor temperature/humidity station that will generate a report online.

• I have an RPi 3 with a DHT22/AM2302 using GPIO22.
• Weewx is running with the Simulator station_type.
• Reports are being generated with NGINX serving them.
• sudo tail -f /var/log/syslog generates the following:

Jul 25 17:28:39  /weewxd: extrasensors: found humidity value of 41.400001525878906 %

Jul 25 17:28:39  /weewxd: extrasensors: found temperature value of 24.299999237060547 C

• I used eyesnz/weewx_pi_sensors

So, Weewx is getting the data, but I'm not sure how to get it into the reporting.  I don't have a physical weather sensor and all I want is the indoor temp/humidity.  I'm guessing I need to use some other device/driver set up than the simulator.  I've seen posts with people using additional/replacement sensors (like the DHT22) but not only using the DHT22.

I'm hoping this is a quick-stupid answer.

Thanks again!

Thom K.

[tho...@gmail.com]

Update: The sensor was reporting with the simulator.  My report was set to US units and the sensor reports C so I used the Calibrate section of Weewx.conf to convert the temp to F.  it appears to be working now.

Not sure if that was the best option.

[gjr80]

The preferred approach for handling such issues is to do the conversion in the code (presumably a WeeWX service) that adds the obs concerned to the loop packet or archive record. More specifically, if you have an obs whose units are/maybe different to other obs of the same type/group then you should check the usUnits field in the packet/record concerned and convert the obs value as necessary before adding the converted value to the packet/record. This way you maintain unit integrity of the packet/archive. Otherwise you risk some other service processing the mixed unit packet/record before your unit conversion occurs and resulting in incorrect output or worse still you may pollute your database.

I had a quick look and found this code that implements a WeeWX service to add BME280 data to WeeWX loop packets. Not saying this is a good or bad example, but if you have a look at the new_loop_packet() method you will see how the usUnits field can be used to check what unit system is being used in the packet and conversions can be done accordingly.

Gary