HackSpace – September 2019

FORGE

bottom of this page, we should see a box called
‘Example Code’.

IT’S ALL IN THE CODE
Rather wonderfully, this is a snippet of code
containing the two key pieces of information an
Arduino sketch on our The Things Uno needs to
connect it to our application on The Things Network.
Copy these (either select and right-click and select
‘copy’, or press the copy button in the upper right-
hand side of the box) and paste them into a text
document or a blank Arduino sketch. Before we
move on to the next part of the tutorial, we are
going to make one last change to the application
we have made on The Things Network. Return to
the Application Overview page – navigate here by
clicking ‘Applications’ in the upper right-hand side
of the page near your profile name – then select
the application we just created. Once back in the
Application Overview, click the ‘Payload Formats’ tab
on the upper right-hand side. On the resulting page,
you should see a box called Payload Format, and it
should show ‘Custom’ in it. Click on this box. In the
drop-down menu, there should only be one other
option, which is CayenneLPP; select this and then
make sure to click the Save button in the lower right-
hand corner of the page.

LET’S GET CONNECTED
Connecting our DHT11/22 sensor board to The
Things Uno is pretty straightforward. Connect
breadboard wires between the DHT11/22 and The
Things Uno 5 V and GND pin sockets. The data pin on
the DHT11 sensor needs to be connected to pin A0
on The Things Uno (as seen in Figure 1).
Returning to the Arduino IDE, we will now upload
the sketch for our sensor to The Things Uno; having

Remember, an

application on The

Things Network can

support multiple

devices – perfect for

large, remote sensor

array projects!

QUICK TIP

SPICY MESSAGES

Cayenne is an IoT platform by a company called

myDevices. CayenneLPP (Cayenne Low Power

Payload) is a format for data packages over LoRa that

allows for some key types of sensors to be integrated

into the Cayenne IoT platform simply via The Things

Network. Put simply, if we can send sensor data in a

CayenneLPP format, a lot of the work to unpack this

data and present it in a straightforward and readable

way is done for us in The Things Network and the

Cayenne myDevices environment.

made some changes and added the keys, we need

to allow it to communicate with the application on

The Things Network. Download the sketch from

hsmag.cc/issue22 and open it in the Arduino IDE.

There are only a couple of changes we need to

make. The first is to check the frequency plan is

correct for our The Things Uno; this is the same

bit of code we replaced earlier in the device info

sketch. In our code, it is set as the ‘TTN_FP_EU868’

European version and will only need changing if you

are using the US frequency plan.

The second change is that you will see a section

in the code which is similar to the code we copied

from the ‘Example Code’ box on the Device

Overview page on The Things Network earlier. (It’s

Figure 5

Success! Data

from our device

successfully being

received by our

application on The

Things Network

The data pin on the

DHT11 sensor needs to be

connected to pin A0 on The

Things Uno

”

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