How Cortex-M3 MCU can become a differentiated 8-bit microcontroller replacement

How can Cortex-M3 MCU take the road of differentiated 8-bit microcontroller replacement?

A while ago, the MCU market was frequently hit by "bad news". Due to the continuous decline in profits of microcontroller products, Fujitsu Semiconductor first announced the sale of its MCU business, and then Samsung Semiconductor had to withdraw from the MCU market. However, there is not only bad news in the MCU market, which is currently overcast. Recently, Silicon Labs announced the signing of a final agreement to acquire Energy Micro AS.

Mr. Zhang Yuangen, who is in charge of the microcontroller business of Shiqiang, a well-known distributor of Silicon Labs' MCU product line, also said: "The main reason for Fujitsu Semiconductor and Samsung Semiconductor to withdraw should be that the MCU profit has declined too much, and the technical advantages are not enough to make up for it. At present, in addition to the international old MCU manufacturers, new manufacturers from Taiwan and mainland China are also pouring in, which has further lowered the price."

The market competition is fierce, and if you don't advance, you will retreat! Especially in the market using the same core, how to implement differentiation and localization of product development and how to improve the cost performance of products are becoming challenges that semiconductor manufacturers must face.

For example, for battery-powered handheld device applications, 32-bit products based on the ARM Cortex-M3 core are probably the most suitable choice for 8-bit MCU replacement solutions, with high cost-effectiveness, lower power consumption and great flexibility. However, even Fujitsu's FM3 series is not working and has to be sold, and TI is almost giving up this market and turning to Cortex-M0 and M4. How will the remaining players achieve differentiated competition and carve out a way out?

Mr. Zhang Yuangen took Silicon Labs' successful Precision32 mixed-signal MCU full series products (including SiM3Uxxx series for USB applications, SiM3Cxxx series for non-USB applications, and SiM3Lxxx series for ultra-low power applications) as an example to analyze how Cortex-M3 MCU has opened up a differentiated 8-bit replacement path in the industrial control instrumentation, smart home, portable medical, IoT wireless terminal, computer peripherals and other markets.



Figure 1. Silicon Labs - Mixed-signal MCU innovation process.


32-bit microcontrollers are the only way for 8-bit manufacturers to expand the application market upward, and the most important thing is how to do a good job of integration. It seems that everyone will integrate an ARM core, but the final effect is different. Zhang Yuangen pointed out: "The Precision32 series uses Silicon Labs' patented Crossbar architecture to ensure maximum flexibility. Coupled with the amazing ultra-low power consumption characteristics of the SiM3Lxxx series, Silicon Labs' Precision32 32-bit MCU series stands out among many ARM Cortex-M3 MCUs." Patented Crossbar

architecture ensures maximum flexibility

Crossbar is Silicon Labs' patented technology. As shown in Figure 1 below, the Precision32 series includes two Crossbars that can connect any I/O function to different pins. The benefits of doing so are obvious. It can optimize the layout, there is no pin conflict, and the peripheral function set can be customized (beneficial to choosing a low-pin count MCU).



Figure 2. Precision32 I/O crossbar-Silicon Labs MCU includes two internal crossbars that enable any I/O function to be connected to different pins.

Designers can configure chip pins to simplify board design, such as configuring output pins close to the chip they are connected to. In some cases, this approach can even allow the use of fewer wiring layers on the PCB, saving costs. In addition, pin reconfiguration can easily cope with the challenges of final board changes.

This approach provides greater flexibility when choosing which functions to connect to the pins and which to leave floating. Flexibility is particularly important when using small packages with a small number of I/O pins. Most other MCUs also offer some configurations, but may only support one or two functions on each pin, limiting the number of options and leading to potential pin conflicts.

Users don't have to worry about the confusion that so many configurations may bring. The application builder (AppBuilder) tool provides a graphical interface that allows designers to configure pins using drag-and-drop functions. Once the configuration is complete, the tool can generate boot code that loads the configuration into the MCU. The tool can work with commercial IDEs, including Keil and IAR, as well as the popular Eclipse. Silicon Labs has adapted Eclipse to support Precision32 products.

Multiple innovative technologies to achieve ultra-low power 32-bit MCUs

The Precision32 series uses a low-power Cortex-M3 core MCU that is comparable to 8-bit MCUs, but with much more powerful performance. It is generally considered by the industry to be the preferred 32-bit MCU for replacing the 8-bit MCU market.

In particular, the SiM3L1xx, which focuses on ultra-low power battery-powered applications, reduces the power consumption in working mode through many key innovations. For example, dynamic voltage regulation can adjust the voltage of internal devices according to changes in application conditions. Compared with other 32-bit MCUs, its integrated high-efficiency DC-DC converter can reduce system power consumption by 40% and increase battery life by 60%! Its performance in sleep mode is even more amazing, with power consumption 5-10 times lower than similar competitors (the lowest sleep current can be as low as 50nA), and power consumption in working mode is 33% lower than similar competitors.

In addition, autonomous peripherals can operate without CPU intervention, and the data transfer manager (DTM) does not require CPU intervention when performing complex data transfers; enhanced direct memory access (DMA) can reduce protocol-related power consumption by 90%, and RAM and register retention states can be quickly woken up within 4μs. This series of MCU products also has a patented LCD controller, whose charge redistribution architecture can reduce display power consumption by about 40% without affecting performance.

In addition, the on-chip oscillator allows the CPU to run at any desired frequency; if an 8MHz external crystal is used, the MCU operating frequency must be a multiple of 8MHz. For the same reason, Silicon Labs allows CPU and USB frequencies to be set independently, rather than in fixed ratios. This flexibility enables system designers to fine-tune CPU frequency to provide the required performance while maintaining minimum speed and power consumption.


Figure 3. SiM3L1xx's impressive ultra-low power performance.

Silicon Labs is also focused on reducing system power consumption, as many MCU applications are powered by batteries or through the restricted levels of the USB specification. For developers, the integration of multiple advantageous analog devices, such as oscillators and USB terminals, can shorten signal path lengths and integrate peripheral components, thereby reducing overall system power consumption.

Development environment - faster, easier to use, power-aware,

graphical simplify embedded application development based on the Precision32 series, Silicon Labs provides a rich set of hardware and software tools, including a unified development platform (UDP) with replaceable MCUs, RF components and other subsystems, which can adapt to the application needs of various developers.

Developers can take advantage of a large number of software and development tools optimized for the ARM architecture, including Keil and IAR tool chains. To accelerate development and code porting between MCU platforms, Silicon Labs also provides Cortex Microcontroller Software Interface Standard (CMSIS) compatible code. The generic peripheral ARM software interface allows peripheral drivers to be reused, simplifying code porting with other ARM-based microcontrollers.

Silicon Labs UDP hardware tools include economical SiM3U1xx-B-DK and SiM3C1xx-B-DK development kits. Enhanced SiM3U1xx-B-EDK and SiM3C1xx-B-EDK development kits contain I/O expansion cards and additional demonstration functions to enhance the development experience.

As one of Silicon Labs' largest domestic distributors, Sekorm is currently conducting an exclusive promotion for Silicon Labs MCU development tools. Sekorm's XXX revealed: "During the event, not only are there discounts on the MCU development kits of these three product series, but the first 100 buyers will also receive a Bluetooth speaker worth 300 yuan!" For more information, please click: http://www.sekorm.com/Ecactivity/82 .



Figure 4: Precision32's complete toolkit shortens time to market.

In addition, Precision32 development tools also have power-aware features. Silicon Labs' free Eclipse-based IDE and AppBuilder software integrate new power estimation and configuration wizard capabilities. This feature is the first designed specifically to achieve the lowest system power consumption.

The Power Estimator provides a graphical view of total power supply current consumption and peripheral current consumption. The raw current value of each peripheral clearly shows the current power consumption, and a pie chart shows the percentage of total power consumption for each peripheral device. The Power Estimator automatically updates when the configuration changes, allowing designers to optimize each mode for the lowest power consumption. The

Power Tips label provides software configuration guidance to help developers minimize current consumption. This feature automatically appears in AppBuilder when the cursor hovers over a configurable setting. The ability to see the power optimization tips label function while configuring the MCU can greatly save development time. A

full range of models meet different application requirements

Precision32 chips can well meet a variety of end applications. For example, the SiM3Uxxx series emphasizes high integration (power consumption characteristics are also good), which is very suitable for barcode scanners, card readers and other peripherals that need highly integrated USB interfaces. And its 6mm package will help meet the form factor requirements of 10Gbps optical transceivers.

For industrial applications, the MCU's 5V-compatible inputs and high-drive outputs are particularly useful in motor control and monitoring. For example, the SiM3Cxxx series has one 6-channel PWM output and two 2-channel PWM outputs, which are ideal for LED dimming control systems.

The main feature of the SiM3Lxxx is ultra-low power consumption. It is very suitable for applications that require high performance, low power consumption, and small packages, such as:

wireless terminal devices for the Internet of Things;
water meters, gas meters, heat meters, etc.;
security and energy management terminals;
smart buildings/homes.

In addition, the SiM3Lxxx has a low-power LCD interface that can reduce display power consumption by 40% and has a small package, making it an ideal choice for battery-powered LCD applications (portable medical; remote control, wireless devices; handheld terminals; smart homes; meters (water meters, gas meters)).

Figure 3 lists the models of the full range of Silicon Labs Precision32 MCUs for reference. There is always one that suits you!



Figure 5. Models of the full range of Silicon Labs Precision32 MCUs.

Zhang Yuangen of Shiqiang concluded: "The power consumption is close to or even better than that of 8-bit MCUs, but the performance is much stronger. In addition, the unique Crossbar architecture of the Precision32 series makes the Precision32 series MCU the first choice for replacing the 8-bit market. In addition, the acquisition of Energy Micro will expand Silicon Labs' 32-bit MCU products to 250 types, and the future prospects are bright."