Pricing
Company
Resources
Developers
Editor’s Note: This guest post is authored by Rob Lauer, Director of Developer Relations at Blues, a trusted hardware partner of Blynk. Rob shares how he built a multi-network refrigerator monitoring system using the Blues Notecard for connectivity and the Blynk platform for cloud dashboards, alerts, and automation. His firsthand experience demonstrates the power of integrating developer-friendly hardware with a flexible IoT software platform to move from prototype to deployment quickly.
When developing connected products, choosing the right tools can be the difference between fast progress and frustrating delays. This real-world project demonstrates how I used Blynk and the Blues Notecard to build and scale a multi-radio refrigerator monitoring system across cellular, LoRa, and Wi-Fi networks—all with the same firmware and cloud logic.
This solution proves that you don’t need to reinvent your stack every time you switch connectivity. With Blynk, I quickly went from a basic prototype to a polished, scalable monitoring system with professional dashboards, no-code alerts, and secure remote visibility.
Before starting this project, the Blues team had heard of Blynk but hadn’t used it in a meaningful way. What stood out was how fast they could set up a secure, professional-looking dashboard and connect devices to the cloud—all with minimal effort.
Blynk’s platform is built around flexibility and developer experience, offering a rich set of tools for both prototyping and production deployments.
What made Blynk stand out:
One particularly useful feature was the ability to configure automations without any code—like sending a push notification if a fridge door stays open longer than two minutes. Blynk also supports OTA firmware updates and device state syncing, making it a solid choice not just for prototypes, but for real-world field deployments. Blynk ultimately proved to be a great balance: powerful for developers, approachable for less technical users, and reliable enough to scale.
This project started with a very well known scenario in the IoT: remote monitoring of some "thing". In this case, it mirrored a restaurant that may have multiple refrigeration/freezer units and the need to constantly track internal temperature/humidity data and the status of the door.
Three nearly identical fridges—each assigned a different Notecard variant: Cellular, Wi-Fi, and LoRa. Each fridge was equipped with a simple reed switch sensor to detect door open/close status, and an embedded microcontroller running the same firmware.
The goal was to create a unified experience for gathering fridge data (like door status), sending it securely via the Notecard, routing it to the cloud with Notehub, and finally visualizing and managing the system with Blynk. The punchline? All three fridges used the exact same codebase and followed the same cloud flow, regardless of their connectivity method.
This setup simulates real-world deployment conditions—think a restaurant chain or food storage operation—where different locations may require different radio technologies based on environment or infrastructure.
Each fridge includes a reed switch to detect door status. A microcontroller keeps track of whether the door is open or closed, and how long it's been in that state. That data is formatted in JSON (using the Arduino SDK in this case) and sent to the Notecard.
The Notecard securely delivers that data to Notehub (Blues’ cloud service), which then routes it to Blynk using a dedicated HTTP integration.
In Blynk, I configured a dashboard that not only shows real-time fridge status but also triggers alerts—like sending a push notification if a door stays open too long.
The best part? This exact setup works the same across Wi-Fi, LoRa, and Cellular—no code changes required.
.png)
The workflow is clean: Notecard handles reliable data delivery; Blynk handles user interaction and automation.
The complete project is documented here on Hackster: The Three Fridge Problem.
The Blues Notecard is a low-power, device-to-cloud data pump designed to make connectivity easy. When you choose Notecard, you’re not locked into a single network type. It’s available in LoRa, Wi-Fi, Cellular, and even Satellite variants—giving you the flexibility to choose the best connectivity method for your deployment environment, all while sharing the same form factor and developer APIs.
Whether you're deploying in a rural area with poor infrastructure, building out a private LoRa network, or working in a facility with strong Wi-Fi and power access, the Notecard fits. Each variant uses the same JSON-based API and connects to Notehub, so you can switch connectivity types without rewriting firmware or rearchitecting your system.
This project highlighted how naturally Blues and Blynk complement each other — especially for developers who want to move fast without getting bogged down in infrastructure.
Blues Notecard delivers global, secure connectivity with minimal setup. There’s no modem configuration or network negotiation required, and no cellular-specific code to write. JSON-based communication and prepaid data plans make deployment straightforward, even across diverse environments.
On the Blynk side, I was impressed by how fast I could build and deploy a dashboard. Their event engine made it easy to add logic like “send a notification if the fridge door’s open more than 2 minutes.” And provisioning new devices? Smooth. It’s a strong platform for developers who don’t want to reinvent the wheel every time they spin up a new project. Together, Blues and Blynk enabled me to focus entirely on the solution. I didn’t need to worry about the transport layer or building custom cloud infrastructure. I went from idea to working prototype in hours — and everything I built is scalable and production-ready.
Tthese tools let you focus on solving problems, not fighting the stack—solid combination for any project that needs secure connectivity and real-time visibility. You can go from idea to working prototype in hours—not days—and everything scales cleanly when you’re ready to deploy more devices. Whether you’re building a smart appliance, deploying environmental sensors, or managing remote assets, the combination of Blues and Blynk is a powerful stack for getting to outcomes, faster.
If you're building connected devices that need to report data and provide real-time visibility or alerts, the combination of Blues Notecard and Blynk is worth serious consideration. The "Three Fridge Problem" is just one example, but this pattern applies to many use cases—from remote monitoring to smart infrastructure and beyond.
You get reliable connectivity, easy cloud integration, and a polished user interface—without having to build everything from scratch. I’ll definitely be looking to Blynk again for future projects.
If you're looking for next steps, try combining the Blues Starter Kit for Cell+WiFi with the Blues Routing Data to Blynk guide.
Explore what you can do:
.png)
