
ARM Cortex microcontrollers for Digital Signal Control at competitive cost
The STM32 F3 microcontrollers are system-on-chip devices based on the Cortex-M4 core with FPU, and are optimized for efficient handling and processing of mixed signals in circuits such as three-phase motor controls, biometrics and industrial sensor outputs or audio filters. They will help simplify design, cut power consumption and reduce pc-board size in consumer, medical, portable fitness, system monitoring and metering applications.
With versatile analog circuitry and the ARM Cortex-M4 with FPU, the STM32 F3 series provides low to medium memory sizes at competitive cost. The Cortex-M4 with FPU core augments the proven Cortex-M3 CPU with additional Digital Signal Processing (DSP) capability, optimized single-cycle and saturating arithmetic instructions, and Floating-Point Unit (FPU), to boost performance over ST’s STM32 F1 Cortex-M3 devices. It positions the new series between the successful STM32 F1 and the best-in-performance-class STM32 F4, which features the Cortex-M4 with FPU core and large memory capacity combined with high-speed 168MHz maximum CPU frequency for complex applications.
The F3 family comprises four product lines, differentiated according to on-chip memory density and integrated peripherals. The peripherals deliver analog integration with such a 12-bit Analog-to-Digital Converter (ADC) offering 5Msamples per second performance. The F30x devices have seven fast comparators with 50ns response time, four programmable gain amplifiers supporting four different gain settings with 1% accuracy, two 12-bit digital-to-analog converters (DACs), and four 12-bit 5Msps analog-to-digital converters (ADCs). This is the fastest ADC performance in any ARM Cortex-M microcontroller, achieving up to 18Msps in interleaved mode. The devices also have two advanced motor-control timers running at up to 144MHz. These allow one microcontroller to manage two motors plus power factor correction (PFC) via its on-chip analog peripherals, in equipment such as home appliances. Among other capabilities of the advanced timers, timing resolution better than 7ns supports new applications such as digital power supplies in telecom infrastructure or data servers, micro-inverters in solar installation and LED lighting.
To help developers optimize code execution time, the STM32 F30x devices have 8Kbytes of SRAM mapped to the instruction bus as Core Coupled Memory (CCM-SRAM). Critical routines loaded in the 8KB CCM at startup can be completed at full speed with zero wait states, achieving 94 Dhrystone MIPS at 72MHz. This compares with 62 DMIPS when executing from Flash or SRAM; equivalent to a 52% performance increase for critical routines. The STM32 F30x series also has up to 40Kbytes of SRAM mapped on the data bus. The 8K CCM-SRAM can also be used for data storage with no performance trade-off. Devices are pin compatible with the STM32 F1 series, and also share the same API, which simplifies migration to higher performing devices.
The STM32 F37x devices are the first microcontrollers from ST to integrate a 16-bit Sigma-Delta ADC on-chip for precision-sensing applications and providing a single-chip solution capable of replacing a discrete general-purpose processor and separate ADC. Up to three 16-bit Sigma-Delta ADCs are integrated on-chip, with separate analog supply from 2.2V to 3.6V, up to 21 single or 11 differential channels, and seven programmable gains per channel.
Other F37x analog peripherals include two fast comparators, three 12-bit DACs, and one 12-bit 1Msps ADC. There is also an enhanced CEC (Consumer Electronics Control) unit, making these devices ideal for consumer multimedia products.
Both series are sampling now to lead customers and are scheduled to enter full production in Q3 2012.
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