Flexible MCU architecture enables easy product upgrades

As market competition becomes increasingly fierce, how to bring new products to market faster has become an issue that engineers are increasingly concerned about. When launching upgraded products that meet higher performance requirements, the flexibility of the original design becomes the key. Highly flexible designs can effectively shorten the design cycle, enable new products to enter the market quickly, and minimize investment, thereby obtaining higher profits. 

Compatibility reduces upgrade investment 

Upgraded products should often have higher performance, integration, lower power consumption, and richer peripherals. How to meet these new requirements with the least investment? If the design of new products can make full use of the intellectual property (IP) of existing peripherals, the investment in existing products will be maintained during the migration, and the peripheral driver software can continue to play a role. 

Taking the core device MCU of the design as an example, if the low-end products based on 8-bit MCUs can use the same development environment as the upgraded new products based on 16-bit or 32-bit devices, it will greatly reduce investment and significantly shorten development time. 

Freescale's "Controller Continuum" is an MCU product roadmap compatible with 8-bit and 32-bit architectures. Controller Continuum provides interoperability across a wide range of consumer and industrial MCU families by using common peripherals, tools and software. 

Flexible MCU Architecture 

The full compatibility of MCUs is reflected in chip pins, peripheral interfaces and development tools. If bit boundaries can be eliminated, 8-bit MCUs can be easily ported to higher-performance 32-bit MCUs. Designers can develop new applications using software and hardware development tools shared by 8-bit and 32-bit devices, and more easily upgrade to the next generation of products as the product matures. 



Figure 1 Controller Continuum product roadmap 

Taking Controller Continuum as an example, it includes six cores: 8-bit RS08, S08 and 32-bit ColdFire V1~V4. As shown in Figure 1, the Flexis series based on the S08 and ColdFire V1 cores is the connection point of Controller Continuum. [page] S08

is a high-speed, low-power core suitable for battery-powered devices. RS08 is a simplified version of the S08 core, designed for devices with less than 16Kb of flash memory and fewer pins. ColdFire V1 takes advantage of the dual-stage instruction fetch pipeline and dual-stage operand execution pipeline of the V2 architecture. At the same time, the V1 core uses the S08 bus structure, which provides an ideal entry point for achieving 32-bit performance. Upward compatibility with all other ColdFire cores ensures that designs can be upgraded to higher performance. 

Comprehensive compatibility 

MCUs based on the ColdFire V1 core use the same peripheral modules and development tools as products based on the S08 architecture, while also providing upward compatibility, effectively simplifying application design. Table 1 compares the main features of the operating modes of the Flexis series CPUs based on S08 and ColdFire V1. The following will use this series as an example to introduce the comprehensive compatibility provided by the Controller Continuum. 

1 Chip Pins 

The ColdFire V1 core uses the S08 single-pin background debug module (BDM) to achieve package pin compatibility. The new version of the debug interface implements a buffer for implementing the BDM readable trace function while maintaining minimal processor overhead. 

Background debug mode (BDM) has been one of the difficulties in maintaining the same pin count. The BDM in the traditional ColdFire is implemented using a three-pin serial interface (clock, data in, data out) with a fourth pin for breakpoints. This BDM supports the ability to insert read/write registers and read/write memory commands in succession, as well as run and stop the processor. Since the S08 is used in lower-end applications and has a very limited number of pins, the debug functions of the traditional ColdFire core have been remapped to a single-pin interface for the V1, which is exactly the same as the S08. 
Table 1 Comparison of CPU modes between the S08 and ColdFire V1 cores 



2 Development Tools 

The biggest challenge in the transition from 8-bit to 32-bit is the development tools. The main development tools must be interchangeable and provide the same simple look and feel to 8-bit users when porting to 32-bit. The CodeWarrior integrated development environment supports software development for Freescale 8-bit and 32-bit microcontrollers. With the latest version of CodeWarrior, users can simply remove the S08 and replace it with the ColdFire V1 core using exactly the same tools, cables, and CodeWarrior tools. Users can simply recompile the code developed in C language with just a few clicks of the mouse. 

Designers can further speed up application development with the help of Processor Expert, a rapid application development tool integrated into the CodeWarrior tool suite. The core of Processor Expert is its expert knowledge base, which allows the graphical interface to only provide valid choices and quickly points out potential resource conflicts, allowing developers to solve such problems in the initial design stage. 

3 Peripherals 

The V1 core has a standardized 8-bit bus to S08 peripherals and tightly coupled 32-bit local memory (flash and SRAM), allowing similar peripheral and memory modules to be used. 

4 At the same time, meeting low power requirements 

Taking the Flexis series as an example, using them to design can minimize the power consumption of the entire final product series, and there is no need to redesign for higher performance and richer peripherals, which is particularly suitable for cost-sensitive applications. The V1 core uses advanced low-voltage, low-power processes to provide a 32-bit MCU with extremely low power consumption in both standby and running modes. In addition, many new applications can be created with its high power density. 

Because ColdFire V1 MCUs have up to 10 times the performance of S08 devices, it is possible to significantly improve product performance in an application without having to increase the frequency. This will be an important advantage for applications that are sensitive to EMC, such as home appliances. 

For example, the highly flexible upgrade route of Freescale Controller Continuum makes it no longer necessary to re-invest and develop resources for consumer and industrial products to expand into new markets. If the latest entry into the market is a low-end product based on an 8-bit MCU, the seamless compatibility of Controller Continuum can be used to design high-performance upgrade products for that market using the same development tools. For example, upgrade from a home wrist blood pressure meter to a medical blood pressure meter, and from a webcam to a security surveillance camera. Thanks to its comprehensive compatibility, Controller Continuum will make it easier for engineering designers to upgrade applications such as medical equipment and monitoring, PoS, metering, and consumer electronics, while saving design time and cost, allowing new products to enter the market faster and have a more competitive advantage.