In weighing up microcontrollers (MCUs) versus microprocessors (MPUs), engineers have to take into account the fundamental architectural differences and the core differences, but also the role IoT has played in blurring the lines between these two technologies as the requirements of IoT applications have driven design changes in MCUs and MPUs.
What is a microcontroller and what is a microprocessor?
MCUs and MPUs serve different purposes in electronic systems. A microcontroller is a compact integrated circuit designed to perform specific tasks within an embedded system. It typically includes a central processing unit (CPU), memory (RAM and flash) and a range of peripheral interfaces, including timers, ADCs and communication protocols, integrated into a single chip.
This level of integration makes MCUs ideal for applications where space, power consumption and cost are all critical factors.
MPUs are designed for more demanding processing tasks. A microprocessor usually only includes a CPU, with memory and peripherals being external components. This allows for greater flexibility and processing power, but it also adds complexity to system design. MPUs are commonly used in applications where complex computations, multitasking or large-scale data handling are requirements, such as in smartphones and computers.
Architectural differences
Integration: One of the most significant differences between a microcontroller and a microprocessor is the level of integration. A microcontroller includes the CPU, memory, and peripherals in a single package, which makes it a self-sufficient unit ideal for simple tasks. A microprocessor, however, requires external components for memory and I/O functions.
Power consumption: MCUs are designed with energy efficiency in mind, making them a natural choice for battery-powered devices such as wearables, remote sensors, and low-power IoT applications. MPUs, while generally more power-hungry, offer better performance and are better suited for tasks where power consumption is less of a concern, such as high-end computing applications.
Processing power: A microcontroller’s CPU is typically less powerful than that of an MPU. Microcontrollers usually operate at clock speeds ranging from tens to hundreds of megahertz and are optimised for handling simple, deterministic tasks in real time. In contrast, microprocessors operate at much higher clock speeds, often in the gigahertz range, and are capable of running complex operating systems and managing multitasking environments.
Memory architecture: Memory in MCUs is generally limited, with the RAM and flash typically integrated on the same chip. MCUs often have relatively small memory, designed to handle specific tasks efficiently without the need for external storage. MPUs, in contrast, rely on external RAM and storage, allowing for much larger memory capacities.
How the IoT is “blurring lines”
MCUs and MPus have traditionally occupied different realms, as MCUs are suited to simple, low-power systems while MPUs have been applied to more complex, performance-intensive applications. The “blurring” of the lines between these two technologies can be attributed to the IoT’s demand for connectivity, Edge computing and real-time decision-making which have caused a shift in design choices.
This includes the increasing processing power in microcontrollers; increased power efficiency in microprocessors; and integrated peripherals in both MCUs and MPUs.
For example, IoT devices require both low power consumption and the ability to handle complex tasks – a requirement which has pushed the boat out for MCUs and MPUs. MCUs are becoming more powerful, with some having multi-core architectures and advanced peripherals. It’s more commonplace now to see MCUs which are equipped with wireless communication interfaces such as Wi-Fi and Bluetooth – meaning they can handle more complex IoT tasks without the need for an external processor.
Microprocessors are becoming more power-efficient, with some designed to operate in low-power modes, making them potential options for Edge computing tasks which require intermittent, high-performance data processing.
An example of this in action was observed when STMicroelectronics announced a new generation of microcontrollers “conscious” of power consumption, which it contextualised as leading to less frequent battery replacements and subsequently, the environmental impact of discarded batteries.
Conclusion
Although the core architectural differences between microcontrollers and microprocessors have long defined their roles in embedded systems, the rise of IoT can be attributed to some convergence in the features offered by MCUs and MPUs, thanks to its low power consumption, real-time processing and complex computation requirements.
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