Proving the Business Case for the Internet of Things

Silicon Labs launches microcontrollers for low-energy IoT applications

Steve Rogerson
May 20, 2015
To simplify USB connectivity for IoT applications such as smart metering, home and building automation, alarm and security systems, smart accessories, and wearable devices, Texas-based Silicon Labs has introduced what it claims to be the industry’s most energy-friendly USB-enabled microcontrollers (MCUs).
An addition to the company’s EFM32 32bit MCU portfolio, the Happy Gecko MCUs are designed to deliver the lowest USB power drain in the industry, enabling longer battery life and energy harvesting applications. They are based on the ARM Cortex-M0+ core and low-energy peripherals.
With more than three billion USB-enabled devices shipping each year, USB is the fastest growing interface for consumer applications and is also gaining significant traction in industrial automation. In today’s IoT world, developers have discovered that adding USB interfaces to portable, battery-powered connected devices can double the application current consumption. These MCUs target that market with energy-friendly USB connectivity.
They contain an energy management system with five energy modes enabling applications to remain in an energy-optimal state by spending as little time as possible in active mode. In deep-sleep mode, they consume 0.9μA standby current with a 32.768kHz RTC, RAM and CPU state retention, brown-out detector and power-on-reset circuitry active. Active-mode power consumption drops to 130µA/MHz at 24MHz with real-world code (prime number algorithm). There is a 2µs wakeup time from standby mode.
Like all EFM32 MCUs, they include a peripheral reflex system (PRS) that enhances overall energy efficiency. The six-channel PRS monitors complex system-level events and allows different MCU peripherals to communicate autonomously with each other without CPU intervention. The PRS watches for specific events to occur before waking the CPU, thereby keeping the core in an energy-saving standby mode as long as possible, reducing system power consumption and extending battery life.
They also have low-energy precision analogue peripherals including an analogue comparator, supply voltage comparator, on-chip temperature sensor, programmable current digital-to-analogue converter and a 12bit analogue-to-digital converter with 350μA current consumption at a 1MHz sample rate. On-chip AES encryption enables the secure deployment of wireless connectivity for IoT applications such as smart meters and wireless sensor networks.
Single-die integration enables developers to reduce component count and bill of materials. It eliminates nearly all the discretes with a crystal-less architecture featuring a full-speed USB phy, on-chip regulator and resistors. They are available in a choice of QFN, QFP and chip-scale packages.
“Happy Gecko MCUs bring the benefits of Silicon Labs’ energy-friendly EFM32 architecture to developers seeking an economical, plug-and-play solution for adding USB connectivity to their battery-powered IoT applications,” said Daniel Cooley, vice president and general manager of Silicon Labs’ MCU and wireless products.
The family is supported by the company’s Simplicity Studio development platform, which helps developers simplify low-energy design. The Simplicity energy profiler enables real-time energy profiling and debugging of code. The battery estimator calculates expected battery life based on an application profile, energy modes and peripherals in use. The configurator provides a visual interface for MCU pin configuration, automatically generating initialisation code. Code developed for other EFM32 MCUs can be reused with Happy Gecko applications.
“The combination of Happy Gecko USB MCUs and our Simplicity Studio development environment enables system designers to connect their 32bit applications to virtually anything with the lowest energy consumption and BoM cost,” said Cooley.
To help developers move rapidly from design idea to final product, the family is supported by the ARM Mbed ecosystem, which includes power management APIs developed by Silicon Labs and ARM. These APIs are designed with low-energy applications in mind, enabling rapid prototyping for energy-constrained IoT designs.
ARM Mbed APIs running on EFM32 MCUs automatically enable the optimal sleep mode based on the MCU peripherals in use, reducing system-level energy consumption. The starter kit supports ARM Mbed out of the box. Silicon Labs has also launched Mbed API support for Leopard, Giant, Wonder and Zero Gecko MCUs.
The Happy Gecko family includes 20 MCU devices providing an array of memory, package and peripheral options, as well as pin and software compatibility with the company’s’ entire EFM32 MCU portfolio. Samples and production quantities are available now in 24-pin and 32-pin QFN, 48-pin QFP and 3 by 2.9mm CSP packages.