Getting Started with Azure IoT Central using ESP8266

Overview
In this getting started tutorial, we will learn how to send
DHT11 Sensor data
from NodeMCU
ESP8266
to
Microsoft Azure IoT Central
. The Internet of Things (IoT) is a network of physical devices that connect to and exchange
data
with other devices and services over the Internet or other network. Anything that can be embedded with the necessary
sensors
and software can be connected over the internet.
Azure IoT Central
is an IoT application platform (aPaaS) that simplifies the creation of IoT solutions. Azure IoT Central provides a ready-to-use UX and API surface built to connect, manage, and operate fleets of devices at scale.
Earlier we learned about
AWS IoT Core
using ESP8266. Microsoft Azure is similar to Amazon AWS IoT Core. This tutorial is for beginners who want to learn about the
Azure IoT Central
for
IoT Applications
. This guide will help you learn to establish communication between NodeMCU ESP8266 with Azure IoT Central. This guide covers setting up Azure IoT Account along with creating IoT Central Applications, Adding a Device, Creating a Template, Publishing Device to Template along with Data Visualization.
Hardware Setup
The hardware setup required for this project is an NodeMCU ESP8266 Wifi Module. And for the sensor part, we will use DHT11 Humidity and Temperature Sensor.
Connect the DHT11 Sensor to NodeMCU ESP8266 Board as per circuit diagram here. Connect the VCC, GND & output pin of DHT11 to NodeMCU ESP8266 3.3V, GND & D4 Pin respectively.
You can use a breadboard for connection or simply use a male-to-female connector wire.
Getting Started with Azure IoT Central using ESP8266
The very first step is to ensure that your PC has been configured to communicate with NodeMCU ESP8266 Board. Then we have to go through Series of steps as follows:
Step 1: Creating Microsoft Azure Account
In order to create a Microsoft Azure Account, you need to have Microsoft Account either
Outlook
or a
Hotmail
Now visit
azure.microsoft.com
. Here fill the details and sign up using the microsoft Account. While creating an Account you will be asked to enter debit/credit card details. There are no charges included for one month.
Finally you will be taken to
Azure Portal
. Hence your account is created now.
Step 2: Setting Up IoT Central Applications
In the Search Bar, look for “
IoT Central Applications
“. Then click on IoT Central Application. You will be taken to following page.
In the subscription part, select your
subscription
. Under
Resource group
, create a new group and give it any name. In the instance details part, give any name to
resource
and
application URL
In the template part select
custom template
and
region
according to your nearest geographical location. Also select the
pricing plan
. Then finally click on
Review + Create
A review page will appear now.
When you get the Validation Passed message, Click on Create. The deployment process will take some time.
When deployment gets completed, you will get the following message on Screen.
Now click on Go to resource.
Now you successfully created IoT Central Applications.
Step 3: Creating Device Templates
We need to create a template or a blueprint for our device, the template will be structured according to the type of data we are expecting from our device. Therefore, what we need to set up first is the device template.
From the above page, you will get an
IoT central Application URL
. Click on the URL and you will be taken to the following page now.
On the left side of the dashboard click on
Device Template
. Then click on
Create a device template
You will find so many ready-made templates created by many vendors. But we need to create our own template. To do that select
IoT Device
. Then click on
Next:Customize
Now give any name to Device Template.
Then Click on
Next
and then
Create
. Hence the device template will be successfully created.
Now we need to add
Capability
to the device template that we created.
Since we will publish
temperature
and
humidity
data, so we will add two capabilities with the following parameters.
Now click on
Save
. Then click on
Views
Select
General Default Views
. Then click on
Generate Default Dashboard View(s)
In the views part, you will be presented with how your data will be presented. I will advise you to change the Temperature and Humidity to “
Last Known Value
”. After this click on “
Save
” and you can go on to
publish
your template.
Step 4: Setting up the Device
After creating a blueprint for our device through the Device template, our next task is to configure the device.
Click on
Devices
and then click on
Add a Device
Give
Device Name
and
Device ID
as anything you want. In the Device Template part, select the device template we created above. Then Click on
Create
Finally a device will be created.
Click on the device name and you will see so many tabs like
about, overview, raw data
, and
Mapped Alies
. The data visualization takes at the overview tab.
At the top left side, you will see an option to Connect. So click on
Connect
Here you will be presented will information you need to connect your NodeMCU ESP8266 to the Azure IoT Central like the DeviceID, Name, Primary Key, and Public Key.
Source Code/Program
The orginal code for this project is written by
Samuel Adesola
. The Code is written in Arduino IDE. Hence you need have pre-installed ESP8266 Boards on your Arduino IDE.
Download the complete project folder from the
Once downloading is completed, extract the folder and there you will find all the source files and library folders. Open the Arduino Sketch from the same folder.
The Arduino Sketch needs some modification. First change the
WiFi SSID
and
Password
to connect to the WiFi Network.

#define WIFI_SSID "***************"
#define WIFI_PASSWORD "***************"
Then you need to change the ID Scope, Device ID, and the Primary Device Key. Copy these parameters from above that you got while setting the device.

const
char
*
SCOPE_ID
=
"*********************"
;
const
char
*
DEVICE_ID
=
"*********************"
;
const
char
*
DEVICE_KEY
=
"*********************"
;
Here is the final code. You can copy this code and then upload it to the NodeMCU ESP8266 Board. Hence communication between Azure IoT Central & ESP8266 can be established using the WiFi Network.

// Licensed under the MIT license. See LICENSE file in the project root for full
// license information.
#include <ESP8266WiFi.h>
#include "src/iotc/common/string_buffer.h"
#include "src/iotc/iotc.h"
#include "DHT.h"
#define DHTPIN 2
#define DHTTYPE DHT11 // DHT 11
#define WIFI_SSID "****************"
#define WIFI_PASSWORD "****************"
const
char
*
SCOPE_ID
=
"****************"
;
const
char
*
DEVICE_ID
=
"****************"
;
const
char
*
DEVICE_KEY
=
"****************"
;
DHT
dht
(
DHTPIN
DHTTYPE
)
;
void
on_event
(
IOTContext
ctx
IOTCallbackInfo*
callbackInfo
)
;
#include "src/connection.h"
void
on_event
(
IOTContext
ctx
IOTCallbackInfo*
callbackInfo
)
{
// ConnectionStatus
if
(
strcmp
(
callbackInfo
->
eventName
"ConnectionStatus"
)
==

)
{
LOG_VERBOSE
(
"Is connected ? %s (%d)"
callbackInfo
->
statusCode
==
IOTC_CONNECTION
_
OK
?
"YES"
:
"NO"
callbackInfo
->
statusCode
)
;
isConnected
=
callbackInfo
->
statusCode
==
IOTC_CONNECTION_OK
;
return
;
}
// payload buffer doesn't have a null ending.
// add null ending in another buffer before print
AzureIOT
::
StringBuffer
buffer
;
if
(
callbackInfo
->
payloadLength
>

)
{
buffer
initialize
(
callbackInfo
->
payload
callbackInfo
->
payloadLength
)
;
}
LOG_VERBOSE