Azure Sphere: The IoT Security Hero You (Probably) Forgot About

April 11, 2025#Azure Sphere #Azure IoT Hub #MT3620 #Dev #IoT #Security #Microcontrollers #Embedded Development

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Let’s be honest Azure Sphere didn’t exactly become a household name when it launched. It was kind of like that one band that opened for Coldplay, you vaguely remember it was good, but no one’s talked about it since.

But here’s the thing: Azure Sphere is awesome. It's secure, smart, cloud-connected, and perfect for serious IoT development. If you’re building a connected device and not thinking about security, you’re basically taping a “Hack Me” sign on it.

In this post, we’re going to show Azure Sphere some love. We’ll go step by step—from unboxing your MT3620 Dev Kit to lighting up an LED and sending data to Azure IoT Hub, all while keeping things locked down tighter than your Netflix password.

What the Heck Is Azure Sphere Anyway?

Azure Sphere is Microsoft’s triple-layered forcefield for connected devices:

Certified Microcontrollers (MCUs): Like the MT3620. Secure silicon, baby.
Azure Sphere OS: A custom Linux-based OS with built-in security features.
Azure Sphere Security Service: Cloud-based protection that handles authentication, OTA updates, and alerts.

Meet Your Gadget: MT3620 Development Kit (EU Version)

This nifty little board is:

Powered by an ARM Cortex-A7 dual-core and a Cortex-M4F for real-time tasks
Packed with Wi-Fi, GPIO, SPI, I2C, UART—you name it
Covered in hardware-level security
Compliant with European power standards (cheers, EU!)

What You’ll Need

MT3620 Dev Kit (EU version)
Micro USB cable
Windows 10/11 PC
Visual Studio 2022 or later
Azure Sphere SDK
Azure account
Coffee (optional but highly recommended)

Step 1: Set Up the Dev Environment

Download and install:

Visual Studio 2022 with Desktop Development with C++ and Azure Sphere extension
Azure Sphere SDK: https://learn.microsoft.com/en-us/azure-sphere/install/overview

Step 2: Plug In and Power Up

Open the Azure Sphere Developer Command Prompt and run:

azsphere login
azsphere device claim

Step 3: Connect to Wi-Fi

azsphere device wifi add --ssid <YourSSID> --key <YourPassword>
azsphere device wifi show-status

Step 4: Create Azure IoT Hub

In Azure Portal:

Create IoT Hub (Free F1 Tier)
Add Device (e.g. mt3620dev)
Copy the Device Connection String

Step 5: Build the Blink Project

In Visual Studio:

Create a new Azure Sphere Blink project
Set the target: AVNET_MT3620_SK
Build and deploy with Ctrl + F5

Step 6: Modify for Telemetry

Update main.c to send telemetry data using the connection string from Azure IoT Hub.

Step 7: Update `app_manifest.json`

Add your IoT Hub to the AllowedConnections list:

"AllowedConnections": [ "your-iot-hub.azure-devices.net" ]

Step 8: Deploy and Confirm

Deploy your app, then go to IoT Hub > Metrics and view "Telemetry messages sent" to verify it's working.

Final Thoughts

This was fun. Azure Sphere might’ve been quiet since its launch, but don’t sleep on it, it’s still one of the most secure platforms for connected devices. And the MT3620 is a great board to prototype with.

So yeah, this is how I did it. From powering up to real cloud data. If I can do it, you can too!