Silicon Labs (Austin, TX) has introduced an energy-friendly 32-bit microcontrollers (MCUs) based on the ARM Cortex-M0+ processor. The EFM32 Zero Gecko MCU family 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. The new Zero Gecko family is the latest addition to the EFM32 Gecko portfolio pioneered by Energy Micro. The family includes 16 cost-effective MCU products designed from the ground up to enable the lowest possible energy consumption for connected devices enabling the Internet of Things (IoT). 

The EFM32 Zero Gecko MCUs feature a sophisticated energy management system with 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. 

  • Deep-sleep mode: 0.9 μA standby current consumption, 32.768 kHz RTC, RAM/CPU state retention, brown-out detector, and power-on-reset circuitry active. 
  • Active-mode: 110 µA/MHz at 24 MHz consumption, real-world code (prime number search algorithm) executed from flash. 
  • Shut-off mode: less than 20 nA consumption.
  • Power consumption further reduced with a 2-microsecond wakeup time from standby mode. 

Like all EFM32 Gecko products, the Zero Gecko MCUs include an energy-saving feature called 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. Leveraging the PRS, 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.

The EFM32 Zero Gecko MCUs feature many of the same power-saving precision analog peripherals included in Silicon Labs’ popular Tiny Gecko, Giant Gecko, and Wonder Gecko devices. These low-energy peripherals include:

  • Analog comparator.
  • Supply voltage comparator.
  • On-chip temperature sensor.
  • 12-bit analog-to-digital converter (ADC) with 350 μA current consumption at a 1 MHz sample rate. 

The EFM32 Zero Gecko devices integrate a programmable current digital-to-analog converter (IDAC). This on-chip precision-analog IDAC generates a biasing current from 0.05-64 µA with only 10 nA overhead. 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 contain a 128-bit Advanced Encryption Standard (AES) hardware block, making them ideal companions for RF transmitters and transceivers used in connected device applications for the Internet of Things.

The EFM32 Zero Gecko family is pin- and software-compatible with Silicon Labs’ broad portfolio of nearly 250 EFM32 Gecko MCU products. This compatibility provides developers with a cost-effective, energy-friendly entry point to higher-performance Gecko devices including the new Wonder Gecko based on the ARM Cortex-M4 core featuring a full DSP instruction set and dedicated floating point unit (FPU). 

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