ST ARM7 Motor Control Development Kit Simplifies Vector Drive

STMicroelectronics (NYSE: STM) announced a new motor control kit, built around the recently-announced 32-bit STR750 microcontroller, which enables the rapid development of high-performance vector-control applications, using both Permanent Magnet Synchronous Motors (PMSM) and 3-phase AC Induction Motors, for cost-sensitive appliance, industrial and HVAC (heating, ventilation and air conditioning) markets. The kit includes all the necessary firmware and hardware – including a 24V DC permanent magnet motor for initial evaluation – to allow the user to be up and running within minutes, and to continue through to development of the target application.

ST STR750-MCKIT ARM7 Motor Control Development KitVector (or ‘field-oriented’) control algorithms are widely used in high-performance drives, providing precise and responsive speed control, and guaranteeing optimized efficiency during transient operations. They also have the practical advantage of using the same framework to control both asynchronous and synchronous motors, a cost-saving feature for development teams dealing with a variety of applications and motor types. In addition, most sensor-less drive algorithms are based on field-orientation methodology, leading to further opportunities to reduce the drive cost.

The STR750-MCKIT is based on the highly integrated STR750 MCU, with ARM7TDMI CPU core, whose rich embedded peripheral set includes a PWM timer with three-phase motor-control features, synchronized with a high-speed analog-digital converter, designed to simplify the implementation of complex vector mode projects. Optimized and fully documented C firmware libraries for the control of both motor types are provided free in the kit, ensuring that most of the motor-control section of the application is already developed. Designing in the industry-standard ARM architecture saves development time compared to the use of a proprietary architecture.

The same hardware platform can be used for both PMSM and AC induction motors, operating at up to 48V; schematics are provided to minimize hardware design time. The kit allows real-time control and monitoring via a PC-based graphical user interface (GUI), or standalone operation using on-board push buttons and trimmers. Segger/IAR J-Link emulation is included, and the Flash programming and real-time debugging capability allows the same hardware and firmware platform to be used from evaluation through to an advanced stage of development, removing the need for the user to build a platform before starting work on the target system. A debugger and programmer are also included.

The STR750 family is the first general-purpose ARM7 Flash microcontroller to support full-spec, 54 MIPS (at 60MHz) operation at both 3.3V and 5V, providing maximum flexibility in electrically noisy environments without additional costs. In addition to motor-friendly timer and ADC systems, its rich peripheral set includes innovative new features such as a backup clock that operates if the main clock fails; a fast startup capability that allows it to begin executing code in only 55µs, instead of typically 1ms required by MCUs using a quartz crystal; and an Automatic Wake Up (AWU) capability that removes the need for an external input to wake from low power STOP or STANDBY modes.

Its advanced timers and security features make the STR750 family particularly suitable for motor control, in appliances such as washing machines, dishwashers and air conditioners; in low and medium range industrial drives and electric vehicles; in HVAC blowers and pumps; and in vending machines and office automation. Serial communications include up to three high-speed (2-Mbit/s) UARTs with support for the LIN protocol, and a serial memory interface for glueless connection to external serial Flash memory.

The family comprises some 30 derivatives, embedding between 64KB and 256KB of Flash memory, plus an additional 16KB bank of Read-While-Write Flash for EEPROM emulation. Up to eight communication peripherals are available, including USB and CAN, as well as a 4-channel DMA controller that significantly reduces CPU loading, and a fast 10-bit ADC. Some members of the family are specified over an extended temperature range of -40°C to +105°C.

The STR750-MCKIT is available now, priced at $895, including a 24V DC PMSM. An AC induction motor for use with the evaluation board can be ordered separately.

About STMicroelectronics
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.