Low Cost, Low Power 32-bit Cortex-M0+ Takes Aim At 8-bit Space

Oct. 17, 2013

Silicon Labs’s EMF32 Zero Gecko uses a 32-bit Cortex-M0+ core to target low end applications bringing high end support like AES encryption to the mix.

Silicon Labs’s EMF32 Zero Gecko (Fig. 1) uses a 24 MHz, 32-bit Cortex-M0+ core to target low end applications bringing high end support like AES encryption to the mix. It is not the first to target the 8- and 16-bit market with a 32-bit platform (see “Cortex-M0+ Family Supports The Low-End Space” on electronicdesign.com) but it does bring a few new things to the arena.

Figure 1. The EMF32 Zero Gecko from Silicon Labs surrounds a 32-bit Cortex-M0+ core with low power peripherals that can interact with each other using the Peripheral Reflex System even when the core is powered down.

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It includes the Peripheral Reflex System (PRS) found on Silicon Lab’s Cortex-M3 platforms. This system allows peripherals to work together even when the core is powered down. Programmers can set up triggers and other signals between peripherals so actions such as the completion of one operation like an ADC conversion can initiate the sending of data from a serial port without the need to wake up the processor. Many of the peripherals are designed to use very little power in deep sleep mode (EM2) further reducing power requirements for an application. For example, there is a regular, high speed USART and a slower but lower power UART. Even the DMA can operate in deep sleep mode that only uses 900 nA.

The cost of the chip starts under $0.50 but it includes features like hardware AES encryption support found on higher end units. This is useful for sensor applications where the chip is communicating in an Internet-of-Things (IoT) type cloud.

The chip has impressive analog support with a 1 Msample/s ADC, a comparator and a current DAC. The DAC can sink or source from 50-nA to 60-mA. There is also an analog comparator.

The chips are available with up to 32 Kbytes of flash storage and 4 Kbytes of SRAM. The smallest package is a 5 mm by 5 mm QFN24.

Silicon Labs provides the Eclipse-based Simplicity Studio free to developers. It also includes the energyAware Profiler, energyAware Designer, and energyAware Battery development tools. These tools help developers tailor applications for optimum power utilization.

Developers can evaluate the EFM32 Zero Gecko using the$69 EFM32ZG-STK3200 starter kit (Fig. 2). It has a built-in SEGGER J-Link debugger plus a memory LCD and capacitive touch buttons for I/O. It has a built-in power monitoring system.

Figure 2. The $69 EFM32ZG-STK3200 starter kit provides its own diagnostics for power analysis.