Solder pin headers to the tiny BME280. The resulting male pins can be on either side of the board. 

Connect the pins to TheThingsUno in the following way:

VCC pin into 3v3 

GND pin into GND

SCL pin into SCL

SDA pin into SDA

Now that we have the hardware connected, let's upload the software. 

Open the Arduino IDE and choose Tools -> Board -> Arduino Leonardo

We also need to load the necessary low-level libraries that we can use to build the Arduino sketch. They can be installed by opening the Arduino IDE and going to Tools -> Manage Libraries.

Use the search tab to search for lora-serialization by Joscha Feth and install the latest version. 

Follow the same process for these libraries as well:

TheThingsNetwork

Adafruit BME280

After these libraries have been installed, copy the Arduino TTN node prototype sketch found on our github. When the .ino file has been saved, go to Sketch -> Verify/Compile. 

If it returns no errors, connect the Arduino via USB port. You may need to tell it which port to use. Then select Sketch -> Upload. Quickly open Tools -> Serial Monitor

With any luck, you will see the board start up and try to connect to TheThingsNetwork. If you see multiple messages about OTAA failing, it is because a TTN gateway is not nearby. If you just want to test your sensor and see your weather data coming off the board, comment out the "ttn.join(appEui, appKey)" line and re-upload the sketch.

--------------- CONTINUE ON IF A GATEWAY IS IN YOUR REGION ------------------

When your sketch has been uploaded and you have a TTN gateway nearby, take the node mobile with a 9V battery and a plug. Log into the TTN console and enjoy your weather data.