MCUs can be applied in various systems, from automotive engine control and implanted medical devices to remote controls, office machines, appliances, power tools, toys, and other embedded systems. They serve as a bridge between reality and the physical world, enabling communication protocols and hardware abstraction layers to interact and perform the necessary operations of devices.

Microcontrollers provide powerful functions in a tiny package and are the preferred brain for embedded devices. Regardless of architecture, all MCUs share some commonalities:

Bit-based MCU core architecture: The bit count (8, 16, 32) used by MCUs (sometimes referred to as bit depth or data width) indicates the number of bits the CPU can simultaneously store and process binary digits, corresponding to the number of bits in the CPU’s registers. Simply put, an 8-bit MCU’s register is 8 bits, but the address bus width can differ from the CPU word length; for example, the original PC’s 8086 is a 16-bit CPU, but the address bus is 20 bits, supporting a maximum of 1MB (2²⁰ Bytes) of memory.

Memory: MCUs have two types of memory. Program memory (flash) stores the code running on the MCU, while data memory (RAM) stores the data used by the code.

Peripheral devices and communication interfaces: These built-in interfaces allow microcontrollers to interact with the outside world, such as sensing temperature or controlling motors.

Security: MCU security is crucial for protecting firmware intellectual property, safeguarding private data within devices, and ensuring service execution.

Since the 1980s, 8-bit MCUs have been at the core of embedded development, and even as 32-bit architectures become more common, they still play a significant role in IoT development. The simplicity and cost-effectiveness of modern 8-bit MCUs ensure they will remain a key component for engineers for years to come.

Here are some examples of popular 8-bit MCU architectures:

PIC: PIC chips were developed by General Instruments in 1975 and now belong to Microchip, powering countless toys, remote controls, and affordable gadgets.

AVR: AVR chips were developed by Atmel and now also belong to Microchip, loved by hobbyists and professionals alike, forming the core of Arduino boards, making electronics accessible to everyone. They are catalysts for innovation and widely used in embedded systems.

8051: Developed by Intel in 1980, this is a truly classic product, with the 8051 thriving in industrial applications and medical devices, highlighting the enduring appeal of simplicity and reliability.

8-bit microcontrollers have several significant advantages over 32-bit microcontrollers.

Cost: 8-bit MCUs are affordable and ideal for budget-conscious projects and hobbyist experiments.

Power Consumption: 8-bit MCUs are much simpler than 32-bit MCUs, making them very suitable for simple applications where power consumption is critical.

Code Size: 8-bit MCUs have smaller code sizes, suitable for applications that do not require much memory.

Ease of Use: 8-bit MCUs are easy to learn and use. With ready-made development tools and online communities, users can start coding right away.

Availability: 8-bit MCUs are readily available, with a wide range of options. Whether you’re building simple robots or smart home sensors, 8-bit MCUs can turn ideas into reality.

Although 8-bit microcontrollers are popular due to their affordability and compact size, they do have some limitations compared to higher-bit microcontrollers.

Limited Storage: One of the main drawbacks of 8-bit microcontrollers is their limited storage space, which can pose challenges for executing complex tasks or processing large amounts of data.

Processing Speed: Due to their limited instruction set, the ability of 8-bit MCUs to execute complex tasks or process large amounts of data may be restricted. This can be a significant drawback for applications that require real-time processing or high-speed data transmission.

32-bit MCUs excel at handling complex tasks, processing large amounts of data, and supporting advanced algebra and floating-point calculations. Here are some examples of popular 32-bit MCU architectures:

ARM Cortex-M: The ARM Cortex-M series is a series of 32-bit microcontrollers designed for embedded systems. It is the powerful force behind smartphones, drones, and wearables.

PIC32: The PIC32 microcontroller is a series of 32-bit microcontrollers developed by Microchip. From industrial automation to robotics, PIC32 can efficiently handle demanding tasks.

AVR32: AVR32 is a 32-bit microcontroller architecture developed by Atmel, bringing the user-friendly AVR world into the 32-bit realm, making it an excellent choice for hobbyists and professionals alike.

RISC-V: RISC-V is an open-source architecture (ISA), the latest development in the RISC architecture family, designed to be simple, modular, and extensible. The RISC-V architecture is becoming increasingly popular due to its open-source nature, allowing for greater flexibility and customization. RISC-V MCUs are widely used in various applications, including embedded systems, IoT devices, and high-performance computing.

Compared to 8-bit microcontrollers, 32-bit microcontrollers have multiple advantages. Here are some of the most significant advantages:

Processing Power: 32-bit MCUs are designed to deliver high performance and efficiency. They are faster and more powerful than their 8-bit and 16-bit counterparts while still being energy-efficient. 32-bit MCUs can support larger RAM and Flash, as well as higher clock speeds. This makes them ideal for applications requiring high-performance computing, such as FFT calculations, high-quality audio or video, high-resolution image processing, and various edge computing applications.

Memory: A 32-bit memory bus provides a wider data path than an 8-bit memory bus, enabling it to transfer more data in a single clock cycle. This leads to faster data transfer rates and improved overall system performance, allowing us to store high-resolution images, complex algorithms, or even entire operating systems.

Peripherals: 32-bit MCUs have multiple advantages in terms of peripherals. They offer more advanced communication interfaces, such as UART, USB, Ethernet, CAN, SDMMC, integrated LCD controllers, etc. These peripherals are essential for many modern applications, including IoT devices, automotive systems, and industrial automation. 32-bit MCUs also provide more advanced ADCs, DACs, advanced timers, programmable counters, and high-precision internal RC oscillators, among others.

Code Efficiency: 32-bit MCUs can pack more instructions per cycle, resulting in faster execution speeds and lower power consumption. This is because they can process more data bits per clock cycle, meaning they can do more with fewer resources. Additionally, 32-bit MCUs can achieve excellent code efficiency, allowing complex operations to be performed using smaller programs.

Library and Driver Availability: Access to a variety of libraries and well-maintained drivers is crucial for efficient software development and seamless hardware integration. When developers can leverage existing libraries and drivers, it can significantly improve productivity and help create robust applications, providing a better user experience.

Despite the dominance of 32-bit microcontrollers in functionality and versatility, they are not a one-size-fits-all solution. Here are some trade-offs to consider before supporting your project:

Power Consumption: The 32-bit architecture increases complexity, making it much more challenging to achieve optimal low-power operation compared to simple 8-bit MCUs. Developers may need to manage more complex energy states and make peripheral trade-offs to achieve similar power consumption metrics.

Complexity: 32-bit MCUs are more complex than 8-bit MCUs, making them harder to program and debug.

Code Size: For less complex operations, the code for 32-bit MCUs may be larger than that for 8-bit MCUs, which can be a disadvantage for memory-limited applications. However, code size largely depends on the code optimization tools used in product development.

In embedded development, choosing the right processor platform is crucial, as both 8-bit and 32-bit MCUs can address different challenges and occupy a place in modern IoT development.

In terms of cost-effectiveness and efficiency, 8-bit MCUs are champions! They are economical and compact, making them ideal for simple tasks like wireless IoT sensors. Their superior efficiency also makes them the preferred choice for battery-powered devices compared to 32-bit MCUs.

On the other hand, 32-bit MCUs offer more processing power and memory than 8-bit MCUs. This makes them more suitable for applications that require higher performance and more memory. However, this comes at the cost of increased complexity.

So, who will win in the IoT space? For basic tasks and budget constraints, 8-bit MCUs can do the job. However, when strong performance is needed for intensive tasks, 32-bit MCUs are more appropriate.