Zero Gecko microcontroller aims for world’s lowest power for Internet of Things

Zero Gecko microcontroller aims for world’s lowest power for Internet of Things

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By eeNews Europe

The 49¢ EFM32 Zero Gecko MCU family is based around ARM’s ‘Flycatcher’ M0+ core and is designed to achieve the lowest system energy consumption for a wide range of battery-powered applications such as mobile health and fitness products, smart watches, activity trackers, smart meters, security systems and wireless sensor nodes, as well as battery-less systems powered by harvested energy for the Internet of Things (IoT).
Silicon Labs has changed the specification of the device from earlier announcements, reducing the clock frequency to 24MHz to match the embedded flash memory to avoid wait states that drain power, and adding a current DAC to power sensors without having to use the microcontroller.
The voltage range has also been increased to 1.85V to 3.8V to support Lithium Vinyl Chloride batteries used in smart meters. This will give a battery life of 10 to 20 years, says Daniel Cooley, director of marketing for MCUs and now based in Oslo following the acquisition of Energy Micro. “A lot of products that target long battery like run up to 3.6V and that just not enough,” he said. The MCU supports 6 to 12 months operation from a coin cell in a wearable application or two to three years in an IoT sensor node, says Cooley.
The EFM32 Zero Gecko MCUs have five energy modes that enable applications to remain in an energy-optimal state, spending as little time as possible in the energy-hungry active mode. In deep-sleep mode, Zero Gecko MCUs have an industry-leading 0.9 μA standby current consumption with a 32.768 kHz RTC, RAM/CPU state retention, brown-out detector and power-on-reset circuitry active. Active-mode power consumption scales down to 110 µA/MHz at 24 MHz with real-world code (prime number search algorithm) executed from flash. Current consumption is as low as 10 nA in shut-off mode. The EFM32 MCUs further reduce power consumption with a 2-microsecond wakeup time from standby mode.
Like all EFM32 Gecko products, the Zero Gecko MCUs include the Peripheral Reflex System (PRS) that significantly enhances system-level energy efficiency. The PRS monitors complex system-level events and allows different MCU peripherals to communicate directly with each other and autonomously without involving the CPU. This means an EFM32 MCU can watch for a series of specific events to occur before waking the CPU, thereby keeping the Cortex-M0+ processor core in an energy-saving standby mode as long as possible and reducing overall system power consumption. This can be used with the iDAC that generates a biasing current from 0.05-64 µA with only 10 nA overhead to power a sensor. The sensor then uses the PRS to wake up the microcontroller.
The low-energy peripherals also include an analog comparator, a supply voltage comparator, an on-chip temperature sensor and a 12-bit analog-to-digital converter (ADC) with 350 μA current consumption at a 1 MHz sample rate. The IDAC provides an accurate bias and/or control capability for companion ICs and other external circuits including amplifiers, sensors, Wheatstone bridges and resistor ladders, thereby eliminating the need for external power amplifier components for many cost-sensitive applications.
The Zero Gecko devices are also the only Cortex-M0+ MCUs containing a 128-bit Advanced Encryption Standard (AES) hardware block. With this built-in hardware AES encryption acceleration support, the Zero Gecko MCUs provide an ideal companion for RF transmitters and transceivers used in connected device applications for the Internet of Things.
“The Internet of Things is a huge and exciting market made possible by low-cost, battery-powered connected devices and wireless sensor nodes that sip nanoamps of energy,” said Geir Førre, senior vice president and general manager of Silicon Labs’ microcontroller products. “The IoT market requires battery-friendly Cortex-M0+ based MCUs that save both energy and system cost. Our new EFM32 Zero Gecko MCUs – shipping now at very cost-competitive prices – enable developers to create embedded systems that are four times more energy-efficient than possible with other Cortex-M0/0+ MCUs.”
The energyAware Profiler debugging tool and the energyAware Designer tool for debugging I/O pin conflicts allow developers to quickly drill down to the exact lines of code that are consuming the most power. The Simplicity Studio tool also includes an energyAware software library built around ARM’s standard CMSIS abstraction layer and supported by leading tool chains. Third-party tools support includes IAR’s Embedded Workbench, Keil’s MDK-ARM and CrossWorks from Rowley Associates.
Samples of Zero Gecko MCUs are available now in QFN and QFP packages with 4 to 32 kB flash sizes, and production quantities are planned for Q4 2013. Product pricing for the Zero Gecko MCUs in 100,000-unit quantities begins at $0.49. The EFM32ZG-STK3200 starter kit is available now and priced at $69.

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