Cortex-M4 set to become ARM's power core

The M4 is an important watershed architecture for Cortex-based microcontroller suppliers because of the DSP capability.

To date Freescale and NXP announced microcontrollers based on the Cortex-M4 processor core, which adds a DSP block to ARM’s popular Cortex-M3.

Now Cortex-M series heavyweight, STMicroelectronics has introduced its first microcontroller based on the ARM Cortex-M4 processor core.

With its STM32 series ST has one of the most popular Cortex-M based microcontrollers which are used in metering, point of sales and building security systems.

Now the Cortex-M4 based STM32 F4 MCUs with their single-cycle DSP instructions will be aimed at digital signal control applications such as high-end motor control, medical equipment and security.

There is pin-to-pin and software compatibility with the existing STM32 F2 parts.

The key to the Cortex-M4 core is its built-in integer DSP, and an optional floating point unit.

As a result it is effectively a digital signal controller aimed at applications in audio, motor control, industrial automation and automotive.

Its instruction set is a superset of the Cortex-M3’s.

When not executing DSP or floating point instructions, the M4 has a similar performance to the M3. Differences start to show once the DSP instructions are invoked.

Power consumption is predicted to be less than 40µW/MHz, with MP3 decode consuming 0.5mW.

Rather than use the Cortex-M4 core, Texas Instruments has opted to integrate its own higher performance C28x DSP core with an ARM Cortex-M3 core.

The Concerto F28M35x microcontroller series, announced in the summer, features a real-time control subsystem based on TI’s C28x core with floating point.

The communications subsystem is based on Cortex-M3 and there are peripherals such as Ethernet, USB On-The-Go, dual CAN, and multiple serial communication ports.

Performance can be tailored to different applications with options for 150/75MHz, 100/100MHz or 60/60MHz on the C28x and Cortex-M3 cores, respectively

Freescale Semiconductor’s Kinetis family of controllers is based on ARM’s Cortex M4 processor core.

M4 is a higher performance version of the Cortex-M3.

NXP Semiconductors also has a dual-core microcontroller which is its first asymmetrical dual-core device integrating ARM Cortex-M4 and Cortex-M0 processors.

It is essentially a programmable DSP device with the Cortex-M4 providing the DSP horse power and the Cortex-M0 providing house-keeping and peripheral control .

“The LPC4000 is not just another Cortex-M4. We’re introducing multi-core processing to microcontroller and DSP applications,” said a spokesman for microcontrollers at NXP Semiconductors.

According to NXP, the combination of the DSP performance with configurable peripherals will make the devices suitable for applications such as motor control, power management and embedded audio.

TI has already integrated the M4 in a 28nm system-on-chip device with four ARM processors on-chip.

The latest generation OMAP 5 mobile applications processor integrates two Cortex-A15 MPCores running at 2GHz and two Cortex-M4 processors.

The new chip has x3 the processing power of the previous OMAP 4 device. “There is nearly 60% average power reduction,” said TI.