Baremetal vs RTOS: Making the Right Choice in Embedded System Designs

By CH Durga Prasad, Embedded Engineer at EurthTech Every embedded project starts with a decision that quietly shapes everything else that follows: Do we go with baremetal or use a Real-Time Operating System (RTOS)? It sounds like a technical formality. But in reality, this is where the architectural DNA of your product is formed. At EurthTech, we’ve lived through both sides of this debate—sometimes learning it the hard way in real deployments.

This is the story of how we evolved through both approaches, and how we help our clients choose the right one—not by theory, but through grounded, field-tested experience.

When Simplicity Works: Baremetal in Its Purest Form

Our first large-scale deployment was a smart soil moisture sensor for a precision agriculture pilot. The ask was simple on paper: sense soil moisture, send the data over LoRa every 30 minutes, and run on a coin-cell battery for months.

We chose an ultra-low-power Cortex-M0+ and built the firmware baremetal—a straightforward super-loop with interrupt handlers for timers and LoRa radio events. It worked. Beautifully. Sleep currents were under 1 µA, timing was precise, and the first 1,000 units went out on schedule and under budget.

At that moment, baremetal felt like the gold standard.

Until the product evolved.

When Requirements Outgrow the Code

Soon, the client returned with feature requests:

• BLE connectivity for on-site configuration

• Secure over-the-air (OTA) firmware updates

• Timestamped event logging

Suddenly, our hand-woven interrupt routines started resembling spaghetti. Interrupts started clashing. BLE stack brought in non-deterministic behavior. Flash writes interfered with radio operations. Debugging became a guessing game.

That was the moment we realized we weren’t just writing firmware anymore—we were building a software system. And it needed structure.

Enter RTOS: Scaling Responsibly

On our next project—a BLE-enabled smart lock—we didn’t make the same mistake. This time, we started with FreeRTOS.

We had tasks for:

• Maintaining the BLE connection and managing pairing

• Responding instantly to button presses

• Handling OTA updates from mobile apps

• Logging lock/unlock events into flash

With RTOS in place, each function became modular. Tasks could fail or restart independently. Shared resources were protected with semaphores. Sleep cycles were efficiently handled with task notifications. Most importantly, debugging became easier because we could isolate behaviors.

It wasn’t just better code. It was better engineering.

Baremetal vs RTOS: The Real-World Comparison

Let’s not oversimplify—baremetal isn’t outdated. It’s lean, fast, and power-efficient when your system is simple. But when concurrency, communication stacks, and OTA come in, an RTOS pays for itself in modularity and long-term maintainability.

Feature	Baremetal	RTOS
Startup time	Instant	Slight delay (scheduler init)
Memory footprint	Minimal	Moderate
Power optimization	Full manual control	Task sleep modes + idle hooks
Code modularity	Low	High (task isolation)
Concurrency handling	Manual (flags, ISRs)	Built-in (tasks, queues, semaphores)
Debugging complexity	Increases rapidly with scale	Easier module-wise debugging
Scalability	Limited	High, suitable for larger features

A Wearable That Taught Us the Difference

A healthcare startup approached us to build a wearable health monitor that tracked SpO₂ and heart rate. The MVP was built quickly on baremetal, and early trials were promising—until BLE sync and flash logging started stepping on each other.

Logs got corrupted. BLE connections dropped during sync. We had to re-architect.

In FreeRTOS:

• Sensor data was sampled periodically in a sampling task

• BLE was handled in a dedicated communication task

• Flash writes were queued and processed in a background logging task

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Battery life improved. BLE reliability increased. And most critically, the code became future-proof for later feature additions like AI-based health alerts.

So, When Should You Use Baremetal?

Baremetal still has its sweet spot. It’s perfect when:

• You have 2–3 functions to manage

• Battery life is ultra-critical

• RAM and flash are limited

• Timing needs are tight but simple

Ideal for:

• Low-cost LoRa/LPWAN sensors

• IR remotes and small peripherals

• Simple USB/HID devices

• BLE beacons with static roles

It’s the right choice when you’re building the equivalent of a firmware calculator, not a smartphone.

And When to Move to RTOS?

Use an RTOS when your design calls for:

• Connectivity stacks like BLE, Wi-Fi, MQTT

• OTA firmware updates

• Flash logging or secure storage

• Modular development by multiple engineers

RTOS is built for:

• Wearables

• Industrial edge gateways

• Smart home hubs and locks

• EV charging controllers and complex IoT nodes

It’s the conductor your growing firmware orchestra needs.

A Hybrid Strategy That Works

In many modern designs—especially with dual-core SoCs—we combine the best of both:

• Use baremetal on a low-power Cortex-M core for tight, deterministic operations like sensor reads.

• Use RTOS (or Linux) on a Cortex-A or higher-end core for UI, connectivity, OTA, and cloud sync.

This layered architecture helps keep real-time performance and power budgets under control while enabling product scalability.

Final Thoughts: Think Ahead, Design Smart

What we’ve learned at EurthTech is this—baremetal and RTOS aren’t opposing camps. They’re two tools in an embedded engineer’s kit. One is great for precision and frugality. The other brings order to complexity.

Start simple. Scale responsibly. When your code begins to feel like it’s holding its breath trying to do too much at once—it’s time to step up your architecture.

If you’re unsure which direction to take, or if your product roadmap includes OTA, BLE, or rapid feature expansion—reach out to us at EurthTech. We've helped clients migrate, scale, and re-architect their firmware for long-term success.

Want to talk through your architecture decisions?

📩 Get in touch with our embedded systems team – and let’s build something that lasts.