Add new blog post about IoT Hub with a temperature sensor

source/_posts/IoTHub-with-temperature-sensor.md

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+---
+title: >-
+  Sending temperature data to Azure IoT Hub with a NodeMCU ESP8266 and a DHT22
+  sensor
+tags:
+  - Azure IoT Hub
+  - Azure
+  - ESP 8266
+  - DHT22
+  - Internet of Things
+date: 2020-04-01 09:32:41
+---
+
+
+## Prerequisite
+Basic knowledge of moving around the Azure Portal.
+If you don't know how this works. There are plenty of guide online.
+(Pre)Programming knowledge.
+
+
+
+## Requirements
+**Install the following software:**
+- Python [Download here](https://www.python.org/downloads/release/python-382/)
+- Arduino IDE [Download here](https://www.arduino.cc/en/main/software)
+- Arduino Libraries
+    - DHT_sensor_library
+    - ArduinoJson (version 5.x)
+    - AzureIoTHub
+    - AzureProtocol_MQTT
+    - AzureIoTUtility
+
+
+- (Optional)VS Code Plugin for arduino [Checkout here](https://marketplace.visualstudio.com/items?itemName=vsciot-vscode.vscode-arduino)
+
+- (Optional)VS Code intellisense [Checkout here](https://cuneyt.aliustaoglu.biz/en/enabling-arduino-intellisense-with-visual-studio-code/)
+
+**Obtain the following hardware:**
+- DHT22 
+- NodeMCU ESP 8266
+- Breadboard + breadboard cables
+
+**Azure cloud**
+- Have an already runningIoT Hub 
+- Azure account with to create an IoT Hub (Free tier is available)
+
+
+## Lets get started
+
+### Setup the board
+To setup the board 3 pins need to be connected from the board to the sensor.
+1. Connect pin `D2` on the board to `DAT` on the sensor
+2. Connect ground `G` on the board to `GND`  on the sensor
+3. Connect 3.3V `3V` on the board to `VCC` on the sensor
+
+<img src="../images/iothub-with-temperature-sensor/diagram-1.jpg" width="800" />
+<br/>
+<img src="../images/iothub-with-temperature-sensor/diagram-2.jpg" width="800" />
+
+### Setup the environment
+1. Install esp8266 driver File -> preference past the following line at:  'Additional Boards Manger Urls:' `http://arduino.esp8266.com/stable/package_esp8266com_index.json`
+2. Install the board: Tools -> Board: -> Board Manager and search on 'esp8266' and install (minimal version 2.5.2)
+3. Select the board: Tools -> Board: and select 'NodeMCu 1.0(ESP 12E Module)'
+4. Install libraries Tools -> Manage Libraries... and typ in the name of the libraries
+5. Configure the compiler so it could compile the Azure IoT packages
+    1. Navigate to and open the `Arduino.h` file (in my case) `%localappdata%\Arduino15\packages\esp8266\hardware\esp8266\2.6.3\cores\esp8266` 
+    2. Comment out line `#define round(x)     ((x)>=0?(long)((x)+0.5):(long)((x)-0.5))` at line 137
+    3. Navigate and open  `platform.txt` at `%localappdata%\Arduino15\packages\esp8266\hardware\esp8266\2.6.3`
+    4. Add the following 2 keywords to line that contains `build.extra_flags=` (line 80) `-DDONT_USE_UPLOADTOBLOB -DUSE_BALTIMORE_CERT`
+6. Copy the example code folder to your arduino sketch directory
+7. Open the Code and press the 'verify/ compile button' or press `CTRL+R` if the code compiles the software is setup correctly
+
+_note: that the code is based on the following documentation: [https://github.com/Azure/azure-iot-arduino](https://github.com/Azure/azure-iot-arduino)_
+
+
+### Setup Azure IoT Hub
+**Configure IoT Hub**
+1. Go to the Azure Portal and search for IoT Hub.
+2. Press the 'Create IoT Hub' button or 'Add' button if there is already some created.
+3. Fill in the field and pres on 'Next: Size and scale >
+
+    <img src="../images/iothub-with-temperature-sensor/azureportal-1.jpg" width="600" />
+4. Here you can change the tier from Standard tier to basic tier (_note: there can only be one free IoT Hub an a subscription_)
+5. Fill in any other fields to your likings and press 'Review + Create'.
+
+**Setup an device within IoT Hub**
+1. Once the IoT Hub is created navigate to that resource.
+2. On the left bar select 'IoT devices' and create a new one. 
+3. Give it a logic name and keep it on Symmetric key and save the device.
+
+    <img src="../images/iothub-with-temperature-sensor/azureportal-2.jpg" width="600" />
+4. Click on the newly created device to see the 'Primary Connection String' This is needed within our code on the next step.
+5. Navigate back to the IoT Hub and select 'Shared access policies' then click on 'service' this should popup a window with more keys. These are also need for the next step.
+
+
+
+### Setup the actual code
+- Open the code folder in the arduino IDE
+- Navigate to `iot_configs.h` and fill in or edit the following fields
+    - IOT_CONFIG_WIFI_SSID
+    - IOT_CONFIG_WIFI_PASSWORD
+    - DEVICE_CONNECTION_STRING
+    - DHT_PIN
+    - INTERVAL
+
+
+### Compile and deploy
+**When all configurations are set it is time to compile the code and send it to the device.**
+- To send the code you need to select the right settings. by default they are oke.
+- Change the COM port to the matching device. (Unplug the device and check what COM port is missing to determine what port you need to select)
+- Once the right COM port is selected press the "upload" button or press `CTRL+U` to upload
+
+    <img src="../images/iothub-with-temperature-sensor/upload.jpg" width="600" />
+<br/>
+
+### Check if data is sending and receiving
+- Create a new console app and include the following code [Get template](https://github.com/Azure-Samples/azure-iot-samples-csharp/blob/master/iot-hub/Quickstarts/read-d2c-messages/ReadDeviceToCloudMessages.cs)
+- Fill in the missing keys that are acquired from the Azure Portal
+- Run the code to seen the packages come in from IoT Hub via the Event Hub.
+- Run the arduino "Serial Monitor" Tools -> Serial Monitor to monitor the outgoing readings and make sure the Baud rate is set to `115200`.
+
+    <img src="../images/iothub-with-temperature-sensor/monitoring.jpg" width="1400" />
+