New ARM Cortex Family from ST Boasts LOW Power

  

June 11, 2007 (Microcontroller.com) - A new ARM Cortex-M3 STM32 family has been announced by STMicroelectronics. Based on the ARM Cortex-M3 core, it is similar to the ARM7 programming model except that the Cortex boasts a Harvard architecture.

Harvard architectures have separate instruction and data buses (and consequentially separate instruction and data memories) and can run with significant speed advantages over linear Von Neumann cores. For deterministic code, the Cortex core can perform a simultaneous instruction and data fetch, which for pipelined architectures results in a single-cycle core. The disadvantage of a Harvard Architecture microcontroller is that because instruction and data memory do not share the same PHYSICAL bus, there can be a reduced level of flexibility in the hardware for some applications.

From a programmer's point of view, STMicroelectronics' implementation of the ARM Cortex does not overlap the instruction and data memory address locations.

At present, the only other significant licensee of the ARM Cortex is Texas Instruments. Luminary Micro of Austin, Texas is also a Cortex licensee; however, Luminary Micro is a startup company with seed funding from ARM, representing ARM's intent to compete with their own licensees and making many major microcontroller manufacturers wary to adopt the Cortex; however, in the words of Carol Brown of ST's U.S. Media Relations, ST expects to compete against Luminary because of "more enticing manufacturing plants".

ARM Cortex Roadmap

The new ARM Cortex STM32 family boasts a low power rating of 0.5mA/MHz. The STM32 ARM Cortex is available in two product families: the "Performance" line boasts a 72MHz core speed with a 24MHz on-chip Flash speed, while the "Access" line has a 36MHz clock and plenty of peripherals.

Other features of the Cortex STM32 family include:

• ARM Cortex core @ 72MHz in 0.18µ CMOS
• ARM Cortex Thumb2 Instruction Set
• Up to 128KByte embedded Flash
• Up to 20KByte SRAM
• 36mA @ 72MHz run
• Power-On Reset
• Power-Down Reset
• Voltage Supervisor
• 2.0V to 3.6V supply
• On Chip 8MHz RC oscillator
• Embedded 4-16MHz oscillator for external crystal
• Separate oscillators for the core (requires external crystal), and 32kHz RTC (uses on-board RC oscillator)
• Single cycle multiply (16x16, 16x32, 32x32 with 32-bit destination)
• Full 32x32 Multiply with 64-bit destination in 7 cycles max.
• Up to 3 16-bit timers
• Dedicated 6 PWM timer
• 7 DMA channels
• CAN or USB (both share a packet buffer, and therefore cannot be implemented together)
• 12-bit ADC with 1µ conversion time
• Up to 3 USARTs
• Up to 2 SPI (18MHz Master/Slave)
• 6 cycle interrupt
• Nested interrupts

ARM Cortex Low Power Operation

Designed for low power systems, the ARM Cortex STM32 microcontroller family operates from a 2.0 to 3.6V power supply and draws as little as 2 microamps in standby mode with reset circuitry active. Four sophisticated low power modes are available.

An Access Line 48-pin STM32 in LQFP with 32KBytes of Flash will sell for U.S. $1.80 in quantities of 10Ku.

About STMicroelectronics
"With headquarters in Italy, the United States, and France, STMicroelectronics is a global leader in developing and delivering semiconductor solutions across the spectrum of microelectronics applications. An unrivalled combination of silicon and system expertise, manufacturing strength, Intellectual Property (IP) portfolio and strategic partners positions the Company at the forefront of System-on-Chip (SoC) technology and its products play a key role in enabling today's convergence markets. The Company's shares are traded on the New York Stock Exchange, on Euronext Paris and on the Milan Stock Exchange. In 2006, the Company's net revenues were $9.85 billion and net earnings were $782 million."