FRANCE: STMicroelectronics (ST) recently introduced its new, 8-bit microcontroller, the STM8S. The STM8S105 and STM8S207 MCUs are meant for industrial and consumer applications. The discussion with Patrice Hamard, 8-bit Product Line Marketing Manager, STMicroelectronics, focused on how MCUs are now beginning to shape the embedded world. Excerpts:

CIOL: How are microcontrollers shaping the embedded world?

Patrice Hamard: ST is reshaping the microcontroller with a solid offer on 8bit that has a strong overlap with STM32 in terms of feature and price. Therefore, we are going to cover the need for embedded functions with only two architectures. Compared to the previous segmentations (8, 16 and 32bit), we are changing it to become 8bit and 32bit only.
 
CIOL: STMicroelectronics recently launched the STM8S, a new 8bit microcontroller. What are the application areas?

PH: The key application areas addressed by the STM8S are industrial and appliances in consistent with the robustness and the reliability. The STM8S family is supporting 5V as well as 3V making it ideal for the platform evolution as well as a good offer for consumer and mass markets.

The cost advantage given with the fine lithography also allows us to propose this family to key customers in PC peripherals and consumer applications.
 
CIOL: Rich feature set is an imperative in the MCU market. How is the STM8S meeting this requirement?

PH: Absolutely, the feature set is driven by the need to reduce the bill of material. The robustness allows simple design and board layout with less filtering. The clock controller gives low noise emission figure reducing the need for shielding. The precise clock allows the suppression of external resonator. The embedded true E²Data suppress the need for additional E²PROM. Safe reset (no grey area) makes the reset system safer suppressing the need for external reset circuit.

The clock system, as well as the two independent watchdog will contribute to pass safety regulations together with our class B libraries.
 
All communications peripherals are available (U(S)ART, I²C, SPI, CAN, LIN), advanced 16bit timers and timebase, fast and precise 10bit ADC.
 
Finally, the 8bit core is one of the most efficient with 20MIPS at 24MHz. Built around 8bit data path, the micro has 16bit registers and 32bit memory memory width.
 
CIOL: Please elaborate on how the STM8 delivers high performance with excellent code compactness?

PH: Thanks to the new CISC instruction set designed in collaboration with ST's C compiler partners, the compactness has been significantly improved. The Harvard architecture with its 3-stage pipeline allows to reach up to 20MIPs @ 24MHz.
 
CIOL: How does it compare to say, Freescale's 8-bit automotive MCU?

PH: The STM8S is covering up to 125degreesC. However this family is addressing industrial. For automotive, there is the STM8A device family. Both are coming from the same vein of design and process. The process used is giving advantage on price, the design is giving advantage in performance. We have proven records on benchmarks.
     
CIOL: Is ST offering or has plans to offer family demonstration boards and instrument cluster reference designs?

PH: Yes, In fact there are currently solutions available in ST with the STM8S/128-EVAL  as well as with third parties like resonance with the REVA KIT. Many reference designs are complete or in progress demonstrating motor control (sensorless brushless DC motors), power management, smart card protocol, capacitive sensing.
 
CIOL: What would be the key factors that influence choice of MCUs today? How does ST stand out?

PH: The key factors influencing the choice of MCUs are various depending on the customer profile, we can list few of them.

The Platform: With the STM8S (4K/128KB, 20to 80pins) combined with the STM32  ST is covering a wide area. Facilitating migration paths from a device to an other.

The Price: The price erosion is still very present. We believe that our technology roadmap is allowing us to profitably propose product and reach the expectation of the market.

The Service and the trust: ST is committed to serve semiconductors and solutions for long term. Our structure is currently a strong asset to give assurance that customers will be served. With the current economic context, it becomes a key argument.
 
CIOL: What are the reasons for the demand in low-power MCUs?

PH: The trend of low power is coming from the increase of application base on battery in consumer and personal care, combined with a strong demand for power meters (electricity, water, gas). Energy saving is important and electronics can contribute a great deal to reduce our overall energy consumption.
 
The STM8S is not specifically aiming low power applications even though the features of the family are good for many low power devices. It is in our plan to introduce later this year a dedicated family to address low voltage/low power arena.
 
CIOL: 8- vs. 16- vs. 32- bit MCUs! Also, affordable prices are also the reason the Asian region is witnessing a migration to 16-bit architectures. Then, why 8-bit?

PH: Everything depends on what we consider to be "affordable" and who we are talking to. For large quantity and for simple functions affordablity is between $.20cts to $.50cts. By construction, a 16bit device cannot be as effective a 8bit product. We even believe that microcontroller prices will decrease and address application served with few discrete device. The main reason is the consistency of architecture.
 
The construction of the 32bit and 16bit are very similar, especially with the new generation of ARM-based products. The only reason to go from 8 to 16bit is for performance improvement. We say that our 32bit portfolio is already overlapping the 8bit segment in performance and in price, leaving no room for 3rd core structure.

Taking a closer look at our portfolio, you will realize that our 32bit is also providing 16bit instruction set, our 8bit is build with 16bit register, 24bit memory address bus.