gned to deliver impressive levels of performance and energy efficiency while retaining all the benefits of working with the open, industry-standard ARM architecture and development environment, the STM32 is offered in two lines: the STM32F103 “Performance” line, with 72MHz clock frequency, provides best-in-class 32-bit MCU performance, while the STM32F101 “Access” line, with 36MHz clock frequency, offers users of 16-bit devices a significant increase in performance at the same 16-bit price levels. Both lines offer from 32K to 128K of embedded Flash memory but differ in maximum SRAM size and peripheral combinations. At 72MHz, executing from Flash, the STM32 consumes only 36mA, the lowest power consumption in the 32-bit market, corresponding to an impressive 0.5mA/MHz.
The Cortex-M3 core was specifically developed to target the low-cost requirements of a broad range of markets and applications where memory and processor size significantly impact device costs. The Cortex-M3 core’s enhanced integrated features include a nested vector-interrupt controller with down to 6 CPU cycles inter-interrupt latency, atomic bit manipulation allowing individual bits to be modified in a single write operation, branch speculation, single-cycle multiply, hardware divide, and the highly efficient Thumb 2 instruction set, leading to superior performance, code density, real-time behavior, and power consumption.
Ideal for battery-operated applications, the STM32 operates from a 2.0 to 3.6V power supply and has a power consumption down to 2 microamps in standby mode with reset circuitry active. Other power-saving features include an integrated RTC with dedicated pin for battery operation and a dedicated 32kHz Oscillator, and four low power modes.
“Until now, 16-bit and 32-bit designers have often been faced with difficult choices, involving compromises between factors such as cost, power, and performance and whether to use industry-standard or proprietary platforms,” said Jim Nicholas, general manager of ST’s microcontroller division. “By eliminating the need to make these compromises, the STM32 will lead the obvious convergence of the 16-bit and 32-bit MCU markets.”
In performance terms, the STM32 family offers up to 30% faster processing than an equivalent ARM7TDMI-based product, or, for the same processing power, STM32 devices require 75% less power. Similarly, the Thumb 2 instruction set of the new core allows designers to reduce code size by up to 45%, almost halving the amount of memory they need to hold their applications. In addition, Dhrystones and other benchmarks show that the STM32 delivers at least twice the performance of the best 16-bit architectures.
The rich peripheral set includes up to 128KB embedded Flash, up to 20KB of RAM, up to two ADCs (12-bit at 1 microsecond conversion time), up to three USARTs; up to two SPI (18MHz master/slave); up to two I2C; up to three 16-bit timers (4 input capture/4 output compare/4 PWM each) and a dedicated 6-PWM timer with embedded dead times for regulation and motor control vector drive applications, as well as USB, CAN, and seven DMA channels. Embedded reset circuitry includes Power-On reset, Power-Down reset and Voltage supervisor, an embedded accurate 8MHz RC factory-trimmed oscillator that can be used as the main oscillator, an embedded 4-16MHz oscillator for external crystal, and dual watchdogs. As a result of this high integration level, only 7 capacitors are needed (in addition to a power supply) for LQFP100 packaged devices.
In addition to traditional applications, such as industrial PLCs, domestic appliances, domestic and industrial security, fire and HVAC systems, and consumer/PC applications such as card readers and biometrics, the new STM32 family is particularly well-suited for portable applications such as glucose and cholesterol monitors where low power consumption is important.
“The low power capability, the ease-of-use and the cost of the STM32 eliminate all remaining obstacles to broad 32-bit usage,” said Nicholas. “We believe the STM32 will meet every designer’s expectation. Further developments of the STM32 family will see an expansion of the current options with larger packages, up to 512KB Flash, 64KB SRAM and with extended features.”
The STM32 is fully supported by development tools from ST and third parties. ST offers an evaluation board, USB developer’s kit and a free software library. Starter kits based on proven tool solutions for ARM core-based devices will soon be available from Hitex, IAR, Keil and Raisonance. Currently the Hitex, IAR, Keil, Raisonance, and Rowley toolchains support the STM32.
STM32 is currently sampling at lead customers and samples will soon be generally available. Both STM32 lines are offered in LQFP48, LQFP64, LQFP100 and BGA100 packages, with
32, 64, and 128K embedded flash options. Distribution pricing (10 Ku) for LQFP devices ranges from $1.80 (Access line, 32K Flash, 48-pin) to $3.60 (Performance line, 128K Flash, 100 pins).