Cortex-M4 is a big number for ARM, and MCU suppliers

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


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

But STMicroelectronics will soon have an M4 chip and Texas Instruments is understood to be planning an M4 launch.

“The M4 has been a significant change for our group as we have always designed our own cores, but from requests from our customers we have decided to introduce this ARM family,” said Jim Stuart, Freescale’s European marketing manager for industrial and multi-market MCUs.

He is aiming to poach existing Cortex M3 users from companies such as NXP as well as stop existing Coldfire users migrate to other suppliers.

The key is having MQX real time operating system and the Code Warrior development environment from Freescale so that a code can be ported to any 8-bit, 16-bit, or 32-bit Coldfire or ARM device, with any combination of peripherals as the low level drivers are generated in real time.

ARM announced the M4 core a year ago. A feature of this 32-bit 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.

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.

In November, NXP Semiconductors introduced 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 Geoff Lees, v-p and general manager for microcontrollers at NXP Semiconductors.

“Equally important are the configurable peripherals that enable LPC4000 users to reduce the need for external Asic functionality,”

According to Lees, 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.

The M4s will be used for offloading real-time processing from the Cortex-A15 cores for mobile handset control functions.

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