It’s Raining Low-Power Microcontrollers

Wow. The Embedded World show in Nuremberg is really shaking the low-power microcontrollers out of the tree this year. Cases in point: announcements of new, low-power 8- and 32-bit microcontrollers from Microchip and Energy Micro (a Norwegian fabless microcontroller company) respectively. Microchip’s 8-bit parts are offered in packages ranging from a tiny 8-lead device to 64 leads. Energy Micro’s parts are available in 20-, 32-, and 64-lead packages.

Energy Micro’s EFM32 “Tiny Gecko” microcontrollers are the little brothers to the Gecko microcontrollers I wrote about last November when the company first announced them at the ARM Techcon 3 conference held in Santa Clara, California. Like their bigger brethren, the Tiny Gecko processors are based on the ARM Cortex-M3 processor core. They consume 180µA/MHz, have a deep-sleep current draw of 900nA, and an “off” mode where the part draws a mere 20nA. There are 13 new members of the Tiny Gecko family with Flash capacities of 8 to 32 Kbytes, RAM capacities of 2 or 4 Kbytes, and 24 or 56 multipurpose I/O pins. Other peripherals included in the Tiny Gecko microcontroller family are a low-energy UART, I2C serial interfaces, A/D and D/A converters, and several counters and timers. Unique to the Gecko microcontroller and continued in the Tiny Gecko line is what Energy Micro calls the “peripheral reflex system,” which allows peripherals to run and communicate autonomously while the CPU sleeps for a big cut in energy consumption. Architecture, instruction set, and peripherals are compatible between the Gecko and Tiny Gecko families, which is the surest way to building a following. Embedded systems designers need broad lines of compatible microcontrollers to accommodate the wide-ranging, diverse needs of embedded design.

To that end, Microchip’s offerings fill in the low-power end of its line. The PIC12F182X and PIC16F182X (PIC1XF182X) microcontrollers—which consume less than 50 µA/MHz and have a rated sleep current of 20nA at 1.8V (30nA at 3V)—extend Microchip’s “Enhanced Mid-range” 8-bit core product line into the realm of 8-pin devices and bring the total number of Enhanced 8-bit core PIC microcontrollers to 16, available in packages ranging from 8 to 64 pins. The family features a range of internal peripherals including Microchip’s mTouch capacitive touch-sensing technology and multiple communications peripherals. The PIC1XF182X microcontrollers include dual I2C/SPI interfaces, more PWM outputs with independent time bases, and a “Data Signal Modulator” that implements a variety of modulation schemes including frequency-shift, phase-shift, and on-off keying along with synchronization and polarity control. Microchip is targeting these general-purpose microcontrollers at a wide range of applications in the appliance (coffee makers, blenders, dishwashers); consumer (vacuum cleaners, printers, remote controls); and automotive markets (LED lighting, keyless entry, body electronics). Here’s a video demonstrating the various low-power operating modes of Microchip’s PIC16LF1823 microcontroller:



Microchip’s Enhanced Mid-range 8-bit architecture employs 14-bit instructions that improve performance as much as 50% relative to 8-bit instructions and 14 new instructions in the Enhanced architecture improve code-execution performance by as much as 40% over Microchip’s previous-generation 8-bit PIC16 MCUs. Significantly, the “enhanced” architecture and instructions extend the instruction address space from 8K to 32K instructions and RAM space from 446 bytes to >4 Kbytes.

Although these new microcontrollers from Energy Micro and Microchip both focus on extremely low-power embedded design and essentially cost a buck each, give or take, they’re really quite different. There’s a substantive difference in both ability and ease of programming between a 32-bit device and an “8-bit” device (I still find it hard to label a processor “8-bit” when it has 14-bit instructions, but Microchip’s parts do operate on 8-bit data) and there are many differences in the available on-chip peripheral devices. Your specific application will likely not need all of the available on-chip peripherals but there are some unique ones in there from both vendors that can make the difference between an easy design and a tough one. Microchip has been in the microcontroller business for decades, has built a substantial ecosystem around its devices, and has recruited a small army of loyal users familiar with its architectures. Energy Micro is the definite newcomer, first announcing products late in 2009. It is inheriting and leveraging the huge ecosystem of the ARM 32-bit architectural empire. You, fortunately, get nothing but tremendous advantage in the form of choice.

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