Sponsored by EM Microelectronic
As IoT continues to demand more compact, power-efficient, and secure wireless solutions, developers are looking beyond generic Bluetooth LE modules. Enter the em | bleu (EM9305) from EM Microelectronic, the world’s smallest Bluetooth® 5.4 SoC, engineered for precision, performance, and longevity in compact connected devices.
This blog serves as a hands-on guide to the em | bleu (EM9305) Evaluation Kit, offering a comprehensive walkthrough from unboxing to power profiling. Along the way, we’ll highlight the key features that make EM9305 stand out—not just as another Bluetooth LE chip, but as a finely tuned, ultra-efficient platform optimized for the next generation of smart, low-power devices.
EM Microelectronic and The Swatch Group: A Legacy of Miniaturization and Efficiency
When you think of cutting-edge semiconductor innovation, a watch company might not be the first thing that comes to mind. But EM Microelectronic, a proud member of the Swatch Group, has quietly built a reputation over the last few decades as a leader in ultra-low-power, highly integrated IC design—starting with the demanding constraints of the watch industry, and now spanning a wide range of high-impact markets.
Founded in Switzerland in 1975, and celebrating their 50th anniversary this year 🎉, EM Microelectronic began by creating custom chips for timekeeping applications, where power consumption, size, and precision aren’t just priorities—they’re non-negotiable. These early challenges became the foundation of EM Microelectronic’s DNA: a relentless focus on efficiency, miniaturization, and performance without compromise.
Today, EM Microelectronic’s portfolio has expanded to include:
- Bluetooth® Low Energy (Bluetooth LE) SoCs
- RFID and NFC transceivers
- Energy harvesting solutions
- Low-power displays and drivers
- Custom mixed-signal modules
EM Microelectronic’s products now power systems in automotive, industrial, healthcare, logistics, access control, smart home, and wearables—while still serving millions of timepieces each year.
EM Microelectronic also works closely with Swatch Group sister companies like Micro Crystal (oscillators) and Renata (batteries) to deliver integrated solutions that combine timekeeping, energy, and wireless capabilities in incredibly compact footprints.
What sets EM Microelectronic apart isn’t just their chip specs—it’s how they apply decades of low-power experience to real-world problems, enabling devices that run longer, take up less space, and deliver more reliability in the field.
So when EM Microelectronic launches a new Bluetooth LE SoC like the EM9305, it comes from a place of deep experience—not only in building radios, but also in architecting complete systems that sip power without sacrificing performance.
What Makes EM9305 Unique?
At a glance, the EM9305 may seem like just another Bluetooth LE SoC. But under the hood, it’s packed with thoughtful engineering and system-level efficiency that make it truly stand out in the Bluetooth LE ecosystem—especially for applications that demand long battery life, compact footprints, and dependable wireless performance.
Ultra-Compact Design
The EM9305 is currently the smallest Bluetooth LE 5.4-compliant System-on-Chip (SoC) available, measuring at a mere 1.8 × 1.8 mm in WLCSP format.
Its minimal footprint makes it a perfect fit for ultra-miniaturized designs, such as:
- Wearables (fitness trackers, rings, wristbands)
- Medical devices (patches, hearing aids, sensors)
- Asset tracking tags and smart labels
- Smart home buttons and compact controllers
When you’re working with limited PCB area and strict industrial design constraints, EM9305 gives you the flexibility to build sleek, modern products without compromising on connectivity.
Industry-Leading Power Efficiency
Where the EM9305 really shines is in its ultra-low-power performance. Every power mode—from deep sleep to advertising—has been optimized for minimal current draw:
- Deep Sleep: as low as 200 nA
- Bluetooth LE Sleep (RC): 610 nA (with 4 KB retention)
- TX @ 0 dBm: 3.4 mA
- RX: 3.1 mA
These numbers translate to years of battery life on small coin cells or energy-harvested systems. And unlike some competitors, these aren’t just theoretical values—they’re backed by real-world measurements using tools like Joulescope (showcased in the demo video towards the end of the article).
Additionally, EM Microelectronic offers PMICs for optimized energy harvesting solutions, supporting both solar cells and thermoelectric generation (TEG).
Integrated, Flexible Power Management
The EM9305 includes a highly configurable power management subsystem that simplifies your system design and extends battery life:
- Operates directly from 1.5V, 3.0V, or 5.0V sources and can go as low as 1.1V (a unique feature not available on many other SoCs)!
- Built-in DC-DC step-down and step-up converters
- Inductorless voltage multiplier for compact power regulation
- Efficient regulators minimize power loss at every stage
This power versatility makes the EM9305 ideal for platforms where supply voltage can vary over time—especially energy-harvesting and multi-chemistry battery systems.
Strong RF Performance
In Bluetooth LE applications, reliable connectivity is critical. The EM9305 delivers on that front with:
- +10 dBm max transmit power
- -97 dBm receive sensitivity @ 1 Mbps
- -103 dBm receive sensitivity @ 125 kbps
These values ensure robust communication even in dense environments—ideal for industrial plants, hospitals, smart homes, or anywhere interference is a concern.
Developer-Friendly SDK and Tools
A great chip means nothing without great tools. EM Microelectronic provides a clean, well-documented, and highly usable SDK that includes:
- Reference examples (GATT profiles, beacon, heart rate, AoA)
- Support for advanced Bluetooth LE 5.4 features:
- Coded PHY for long-range applications
- PAwR for electronic shelf labels and broadcast control
- Angle of Arrival (AoA) for direction finding
- Peripheral drivers (GPIO, I2C, SPI, ADC, etc.)
- CMake-based build system
- MetaWare-compatible debugger support
Whether you’re a seasoned Bluetooth LE developer or exploring new platforms, the EM9305 SDK gets you up and running quickly and supports full customization as your project scales.
Specs alone don’t tell the full story. What makes the EM9305 truly unique is how it combines:
- Ultra-compact form factor
- Best-in-class low-power operation
- Broad Bluetooth LE 5.4 feature support
- Integrated power management
- Reliable RF performance
- A developer-first SDK and toolchain
Note: the toolchain used is the MetaWare toolchain by Synopsys and is provided free of charge to EM’s customers (upon request), allowing customers to develop their products and solutions without any licensing constraints.
All of this is backed by EM Microelectronic’s decades of experience in low-power design for wearables, industrial applications, and timekeeping systems.
The result? A platform that enables more than just connectivity—it enables differentiation, efficiency, and long-term product success.
But Wait… It’s not ARM? Understanding ARC and Why You Shouldn’t Worry
One of the first questions developers ask when evaluating a new Bluetooth LE SoC is: “Is it ARM-based?” And understandably so—ARM Cortex-M cores have become the de facto standard for embedded development. They’re familiar, well-documented, and supported by a massive ecosystem.
But the EM9305 doesn’t use an ARM core. It’s built on the ARC EM7D processor, a 32-bit RISC architecture developed by Synopsys and purpose-built for ultra-low-power embedded applications.
So… What is ARC?
ARC (Argonaut RISC Core) is a family of compact, configurable CPU cores designed to maximize performance-per-milliwatt in embedded systems. While not as widely known as ARM outside of semiconductor circles, ARC is actually found in billions of chips worldwide—from audio codecs and SSD controllers to sensor hubs and wireless SoCs.
The ARC EM7D core in the EM9305 is optimized specifically for:
- Small code size
- Low active power and leakage
- Fast wake-up times
- Deterministic performance for real-time tasks
But I’ve Never Used ARC Before…
That’s a common concern, and it’s one EM Microelectronic has anticipated and addressed.
Here’s the good news: you don’t need to learn a new architecture to be productive with the EM9305. The SDK and tooling provided abstract the core completely. Development feels just like working on any other embedded platform:
- You write firmware in standard C
- You build using CMake or a command-line toolchain
- You debug using MetaWare-compatible tools, with clear symbol output and step-through support
- You don’t need to deal with ARC assembly unless you’re optimizing at the lowest level (which most developers won’t need to do)
The SDK also includes clean, modular examples with reusable drivers and reference GATT-based applications—so you’re rarely starting from scratch.
Comparing ARC and ARM at a High Level
| Feature | ARM Cortex-M | ARC EM7D (in EM9305) |
|---|---|---|
| Architecture | 32-bit RISC | 32-bit RISC |
| Code Density | Good | Excellent (smaller binaries) |
| Toolchain | GCC, Keil, IAR | MetaWare, ARC GCC |
| Ecosystem Size | Very large | Moderate but targeted |
| Power Efficiency | Strong | Exceptional |
| Real-time Performance | Good | Tuned for deterministic RT |
| Customization by SoC Vendor | Limited | High (core can be tailored) |
The ARC EM7D isn’t just an alternative—it’s actually better optimized for ultra-low-power wireless applications than some general-purpose Cortex-M cores. EM Microelectronic chose it deliberately to achieve a tighter, more efficient chip design without sacrificing development ease.
Focus on What Really Matters
The key takeaway? It’s not about the architecture. It’s about the developer experience.
EM Microelectronic provides everything you need to work comfortably and productively on ARC:
- A familiar SDK structure
- A toolchain that “just works”
- Solid documentation and application notes
- Examples that compile, flash, and run out of the box
So if you’re hesitating because it’s not ARM-based, don’t. With the EM9305, you won’t even notice the difference—except when you measure your battery life.
Common Questions Developers Have About ARC
Switching away from the familiar always raises questions. If you’re used to working with ARM Cortex-M cores, you might have a few concerns about using an ARC-based SoC like the EM9305. Below are some common objections—and why they shouldn’t hold you back.
“I’ve never heard of ARC—why would I choose a less-known architecture?”
ARC isn’t new or niche. In fact, ARC cores are used in billions of chips across SSD controllers, sensor hubs, and Bluetooth LE devices. The EM9305’s ARC EM7D core is highly optimized for low-power embedded systems, making it an ideal fit for wireless IoT.
Here are just a few examples of ARC being used in products:
- Starblaze MB1000 Enterprise SSD Controller uses the Synopsys DesignWare ARC HS38 processor for high-performance SSDs
- QLogic storage controllers (used in disk drives, RAID devices, tape drives, and SAN switches) incorporate ARC processors, specifically the ARCtangent-A4
- ARC processors are also integrated into flash storage controllers for SSDs and similar devices
- “Toshiba, ARC in configurable processor collaboration”
“What about the toolchain—will it be hard to use?”
EM Microelectronic provides a complete SDK and toolchain that includes:
- A MetaWare-compatible compiler and debugger
- A CMake-based build system with modular examples
- Command-line flashing tools and clean project structure
You can be productive without needing to learn any low-level ARC internals.
“Do I need to learn ARC assembly or change how I write firmware?”
No. The EM9305 SDK is written in portable, standard C. You use the provided APIs just like you would with any Bluetooth LE SDK. Unless you’re optimizing at the lowest level, you won’t need to write or understand ARC assembly.
“Will it integrate with my development workflow or CI setup?”
Yes. The SDK supports CMake, making it CI/CD–friendly and easily integrated into automation pipelines. Build and flash operations can be scripted and deployed across teams.
“Is there an easy way to test and evaluate it?”
Absolutely. The EM9305 Evaluation Kit is designed for quick evaluation:
- Easy-to-install SDK and toolchain (free)
- Sample applications readily available in the SDK
- CLI flashing tools
You can get from unboxing to running a Bluetooth LE app in under 30 minutes.
“What if my manager or customer insists on ARM?”
Remind them that ARC enables smaller die size, lower leakage, and longer battery life—especially in ultra-compact or power-constrained designs. EM Microelectronic has a long-standing track record and ships millions of ARC-based chips across multiple markets.
Choosing ARC in this context isn’t a risk—it’s a purpose-driven decision.
Summary
| Concern | Reality |
|---|---|
| ARC is obscure | Used in billions of devices worldwide |
| Tools are limited | Full SDK, debugger, build system provided |
| Need to learn new architecture | Standard C development with abstracted APIs |
| Doesn’t fit CI/CD | CMake-based, CLI friendly |
| Hard to evaluate | EVK is plug-and-play with demo apps |
| Not “mainstream” | Proven reliability, lower power, tighter integration |
The EM9305 may be based on ARC, but the development experience is polished, well-supported, and friendly.
Don’t let unfamiliarity keep you from evaluating a platform that might be exactly what your next product needs.
Unboxing the EM9305 Development Kit
Out of the box, the DVK includes the following components:
- An EM Microelectronic EM9305 DVK board.
- An EM Microelectronic EMREF9305QFN module.
- A Digilent JTAG cable, allowing on-chip debugging.
- A USB to USB mini cable to power the system and communicate with the PC, allowing, but not limited to, loading the FW and configuring the device.
EM9305 DVK Unboxing, Development, Testing, and Current Measurement
Summary & Next Steps
The EM9305 delivers on its promise: a compact, efficient, and accessible Bluetooth LE SoC. Whether you’re evaluating for wearables, tags, sensors, or custom devices, this kit provides:
- The hardware
- The SDK
- The toolchain
- The documentation
- Easy-to-build and use sample applications covering a variety of use cases
…and removes any barriers to getting started, regardless of whether you’re familiar with ARC or not.
Resources and Useful Links
- em | bleu (EM9305) Product Page
- EM9305 Datasheet
- EM9305 DVK factsheet
- EM9305 Bluetooth Module Factsheet (used with the DVK)
- EM9305 DVK from Digikey (to purchase for evaluation)
