EFM32 microcontrollers target very low active power consumption, reduced processing time, very fast wake-up time and ultra-low standby current. To achieve such characteristics, Energy Micro has listed 10 factors for microcontroller design improvements:
1. Very low active power consumption: EFM32 microcontrollers target significantly reduced active mode power consumption. At 32 MHz and 3V the MCU consumes 180 μA/MHz while running real life code from the internal Flash memory.
2. Reduced processing time: Energy Micro build the EFM32 Gecko microcontroller using the 32-bit ARM Cortex-M3 processor core which ARM developed for response and power sensitive applications. Tasks can therefore be executed with few clock cycles which dramatically reduces the active period.
3. Very fast wake-up time: Low power systems continually switch between active- and sleep modes. By minimizing the inefficient wake-up period between deep sleep modes and active mode as little energy as possible is used before the CPU starts processing its tasks.
4. Ultra-low standby current: Low energy usage in standby modes while still performing basic operations is useful for low power applications, and the sleep modes includes RAM and CPU retention, Power-on Reset and Brown-out Detection safety features plus and a Real Time Counter.
5. Autonomous peripheral operation: The EFM32 peripherals can operate in low energy modes without using the CPU. Using autonomous peripherals, an application can reduce power consumption while still performing very advanced tasks.
6. PRS - Peripheral Reflex System: It is possible to directly connect one peripheral to another peripheral without involving the CPU. With this system a peripheral can produce signals which other peripherals can consume and instantly react to while the CPU remains asleep.
7. Well architected Energy Modes: EFM32 microcontrollers have 5 efficient energy modes which give system designers the flexibility to optimize their application for highest performance and longer battery life.
8. Energy efficient peripherals include: a LCD controller driving 4x40 segments at only 0.55 uA, a Low Energy UART performing full communication at 32 kHz while consuming only 100 nA, a 12-bit ADC performing 1 million samples/sec at only 200 uA, the Analog Comparator using as little as 150 nA, the Hardware accelerator for 128/256-bit AES key encryption and decryption in only 54/75 cycles
9. AEM - Advanced Energy Monitoring: The Advanced Energy Monitoring system makes it possible to accurately view a prototype's current consumption data in real time, enabling early identification and removal of adverse current drains. The tools also integrate a full J-Link from Segger, for easy debugging and programming.
10. energyAware Software: The free energyAware software suite supports the EFM32 Gecko development tools. This includes code examples, CMSIS libraries and a Profiler that reads the kits Advanced Energy Monitoring (AEM) system data and enables simple graphical visualization and optimization of application energy consumption and code.
Energy Modes
A wide selection of energy modes available in the EFM32 makes it possible to optimize a systems energy consumption to meet low energy requirements both in active- and sleep modes. The very short transition time between the energy modes in combination with the autonomous operation in the low energy modes favor long sleep times. In all but the deepest energy mode application data is maintained with full RAM retention.
In active mode the industry standard Cortex-M3 RISC processor delivers high performance in terms of computational performance, system response, and low power consumption. Challenging tasks are handled by the processor and the highly integrated peripherals, and the fast interrupt handling and low latency makes the EFM32 very well suited for battery operated applications and systems with critical response times.
Peripherals for autonomous operation
EFM32 microcontrollers use various control techniques for efficient energy management. Low power and customizable peripherals surround the powerful 32-bit ARM Cortex-M3 processor and enable fast autonomous operation and reduce the need for CPU. High overall integration reduce a systems need for external components. Peripherals can react and respond to input from external or internal triggers without any CPU intervention via a system called the Peripheral Reflex System.
