July 14, 2012 - STMicroelectronics, which created a new sensation in the MCU field with its domestic Cortex-M3, is making headlines by announcing the STM32F3, equipped with a Cortex-M4 core, following the announcement of the STM32F4, which features a high-performance MCU-class Cortex-M4 core, last year.

The existing STM32F4 is ST’s top-tier Cortex Core MCU currently in existence, boasting the best performance with 168MHz and 210 DMIPS. However, there was some resistance due to its high price when trying to access the low-end market that requires FPU and DSP functions. It appears that the new STM32F3 addresses this issue and adds specifications that were lacking in the existing STM32F1, thereby enabling a more stable product configuration for the existing market.

Currently, the visible optimized parts include DACs, Advanced ADCS, Temp Sensor, Comparators, RTC, and Op Amps, which conventional MCUs could not replicate. By enabling all of these to be replicated in the F3, it appears that this will contribute to significantly reducing BOM costs.

With this announcement, ST is now able to offer a total of over 350 different solutions. This means that the benefits provided by STM32 devices and the related ecosystem can now be applied to applications such as high-performance motor controllers or embedded digital audio, which previously required high-performance analog and basic digital signal controllers.

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The ARM Cortex-M4-based STM32 F3 family with an integrated FPU consists of four different product lines depending on the on-chip memory density and the peripherals installed. The peripherals achieve outstanding analog integration, delivering best-in-class performance through features such as a 12-bit ADC providing 5M samples per second. This superior analog integration offers designers the greatest flexibility to implement advanced system functions and characteristics without the need to add additional components to the PCB.

The STM32 F30x device features seven fast comparators with a response time of 50ns, four programmable gain amplifiers with 1% accuracy and supporting four different gain settings, two 12-bit DACs, and four 12-bit 5Msps ADCs. This represents the fastest ADC performance among ARM Cortex-M-based microcontrollers, achieving up to 18Msps in interleave mode. Because the STM32 F30x device is equipped with two advanced motor-control timers running at up to 144MHz, it is possible to control two motors and Power Factor Correction (PFC) via on-chip analog peripherals in products such as consumer electronics using a single microcontroller. Among the various capabilities of these advanced timers, the excellent timing resolution of 7ns or more enables modern applications such as digital power supplies for telecom infrastructure or data servers, micro-inverters for solar devices, and LED lighting to benefit from the power-saving and cost-effective features and scalability of the STM32 family.

To enable developers to optimize code execution time, the STM32 F30x device incorporates 8 KB of SRAM mapped to the instruction bus as core-coupled memory (CCM-SRAM). During initialization, critical routines loaded into the 8 KB CCM are completed at maximum speed without any waiting, enabling 94 Dhrystone MIPS (DMIPS) at 72 MHz. This compares significantly to 62 DMIPS when running on Flash or SRAM, representing a 52% improvement in critical routine performance. The STM32 F30x also features built-in 40 kbyte SRAM mapped to the data bus. 8K CCM-SRAM can also be used as data storage without performance degradation. These devices are pin-compatible with the STM32 F1 series and share the same APIs, allowing for a simple transition to devices with enhanced performance.

The STM32 F37x device offers a variety of peripheral capabilities. As the first ST microcontroller to feature an on-chip 16-bit Sigma-Delta ADC, it enables the STM32 family to deliver a wide range of precision-sensing applications and provides a single-chip solution that replaces designs using a general-purpose processor and an external ADC separately. Up to three 16-bit Sigma-Delta ADCs are included in the on-chip solution, and separate analog supplies are provided from 2.2V to 3.6V. Additionally, up to 21 single or 11 differential channels are available, each featuring 8 programmable gains.

Other STM32 F37x analog peripherals include two fast comparators, three 12-bit DACs, and one 12-bit 1Msps ADC. It also includes an enhanced CEC (Consumer Electronics Control) unit, making it ideal for consumer multimedia products. Compared to the STM 32 F1 series, the STM32 F37x device provides an SoC solution that can reduce BOM (material costs) and simplify board design.

Key features of STM32 F30x/F37x
1. Parity bit SRAM and CCM-SRAM for secure software data and code execution
2. Memory Protection Unit (MPU)
3. Capacitive touch-sensing capability (24 keys)
4. Supports USB and CAN connections
5. Communication Peripherals: SPI 18Mbps, I²C 1MHz (Fast Mode Plus), USART 9Mbps
6. Sub-ppm RTC (real time clock) equipped with a hardware calendar
7. Four power saving modes, including a 5µA Stop mode with a waking-up capability to wake up communication peripherals with a fast startup time.
8. Implementation of 2µA standby mode in RTC operation state
9. Less than 1µ in Vbat mode (battery backup)
10. Debug Mode: Serial Wire Debug (SWD), JTAG Interface, Cortex-M4 ETM
11. Power Supply: 2.0V ~ 3.6V or 1.8V+/-8% (Specific sales type)

For orders of 1,000 or more, the pricing for the STM32 F30x series ranges from a base price of $2.54 for the 128Kbyte Flash STM32F302 in an LQFP48 package to up to $3.86 for the 256Kbyte STM32F303 in an LQFP100 package. The pricing for the STM32 F37x series varies from $2.24 for the 64Kbyte STM32F372 in an LQFP48 package to $3.69 for the 256Kbyte STM32F373 LQFP100. Pricing options for larger unit orders are available upon inquiry.

Both series are currently being sampled with major customers, and full-scale mass production is scheduled to begin in the third quarter of 2012.