Exploring the role of the microcontroller in modern embedded system design

In the world of embedded systems, microcontrollers are no longer simple circuits executing basic instructions. Today, over 30 billion MCUs are shipped annually worldwide (source: IC Insights), and the global market is expected to reach USD 47 billion by 2028. With growing demands for performance, connectivity, and energy efficiency, MCUs have evolved into advanced platforms integrating artificial intelligence capabilities, wireless communication, and extensive edge computing functionalities.

In this article, we will explore what embedded microcontrollers truly are, examine their structure and architecture, discuss their various types, and analyze how they are applied in modern technologies.

Processor, memory, and communication: the building blocks of microcontroller design

A microcontroller is a specialized integrated circuit that incorporates all the essential electronic components necessary to independently perform control, monitoring, and communication tasks within embedded systems. Its central element is the Central Processing Unit (CPU), whose primary function is to execute logical and arithmetic operations and process program instructions. The CPU manages data flow and oversees the overall operation of the system.

In addition to the central processing unit, semiconductor memories play a key role in the structure of a microcontroller. A typical microcontroller features three main types of memory:

• Program memory (usually Flash or ROM), where the code that controls the entire device is stored;
• Data memory (RAM), used for storing operational variables during program execution;
• Non-volatile memory (EEPROM), enabling the permanent storage of configuration data, device parameters, or measurement results even after power is switched off.

A very important component of the architecture is the set of general-purpose input/output ports (GPIO), which allow the microcontroller to communicate with the external environment. GPIO pins can be configured either as inputs — receiving signals from sensors, switches, or other electronic circuits — or as outputs — controlling actuators such as relays, motors, or LEDs.

Peripheral modules, on the other hand, are additional functionalities integrated into the microcontroller’s structure, significantly expanding its range of applications. The most important peripheral modules include:

• Analog-to-Digital Converters (ADC) – allowing the measurement of analog voltage values, e.g., from temperature, light, or humidity sensors.
• Digital-to-Analog Converters (DAC) – used to generate analog signals from digital data, for instance to control analog actuators.
• Pulse Width Modulation (PWM) modules – enabling the generation of signals with adjustable pulse width, used for controlling motors, LED lighting, or power regulators.
• Communication interfaces – facilitating data transfer between the microcontroller and other components or peripheral devices. The most commonly used interfaces include UART (asynchronous serial communication), SPI (synchronous serial communication), I²C (communication with multiple peripherals over a shared data bus), and ethernet (for reliable and high-speed network communication in industrial and IoT applications).

Tab. 1 Key Peripheral Modules

Other important components of microcontrollers include clock systems (oscillators) that generate timing signals for the CPU and peripherals, as well as internal reset circuits and watchdog timers that monitor the correct operation of the device. Furthermore, modern microcontrollers are often equipped with advanced security mechanisms designed to protect stored data from unauthorized access and safeguard the system against disruptions or software errors.

Microcontrollers explained: choosing the bit width for your project

Microcontrollers can be classified in various ways; however, the most common distinctions are based on data bus width, architecture, and application specificity. The basic division includes 8-bit, 16-bit, and 32-bit microcontrollers.

8-bit microcontrollers are designed for simple applications where computational requirements are minimal, and low power consumption and low production cost are of primary importance. They feature a simple architecture and are commonly used in devices such as keyboards, battery chargers, basic automation systems, and electronic toys. Examples include devices from the AVR family (e.g., ATmega328) and PIC microcontrollers by Microchip.

16-bit microcontrollers offer greater processing power and more advanced features compared to their 8-bit counterparts. They are used in applications where faster data handling, more precise control processes, or more complex algorithms are required, such as motor controllers, advanced measurement systems, or medical devices. A popular example from this group is the MSP430 family by Texas Instruments, well-known for its low-power performance.

32-bit microcontrollers represent the most advanced category, combining high computational performance with great application flexibility. They are most often based on the ARM Cortex-M architecture and support advanced real-time operating systems (RTOS), complex signal processing algorithms, and multi-channel communication. They are utilized in applications such as IoT systems, multimedia devices, industrial control systems, and security systems. Notable examples include STM32 microcontrollers from STMicroelectronics and the ESP32 series from Espressif Systems.

Performance, power, and cost: finding the right microcontroller balance

As the demand for smarter, smaller, and more efficient devices grows, so does the diversity of available microcontroller architectures. Understanding the distinct characteristics and design philosophies behind each family is essential for engineers, developers, and educators working across the embedded landscape.

ARM Cortex-M – The most popular group of 32-bit microcontrollers based on RISC architecture. The Cortex-M0/M0+ series (e.g., STM32G0, NXP Kinetis KE) is optimized for ultra-low power consumption and cost efficiency. Cortex-M3 and Cortex-M4 (e.g., STM32F4, LPC4300) offer performance suitable for real-time operating systems (RTOS) and advanced peripheral control. Meanwhile, Cortex-M7 and Cortex-M33 microcontrollers (e.g., STM32H7, i.MX RT1170) provide high throughput for DSP operations and enhanced system security thanks to integrated TrustZone technology.

AVR (Microchip) – 8-bit microcontrollers known for their very simple architecture, low power consumption, and fast response times. They are popular in low-cost systems and IoT devices with limited computational requirements. Examples include the ATmega328P (Arduino Uno) and the ATtiny85 (basic sensors). “Arduino brought microcontrollers out of the shadows of engineering labs and into the hands of artists, students, and makers”, said Massimo Banzi, co-founder of Arduino.

PIC (Microchip) – A broad family covering 8-bit (PIC16 series), 16-bit (PIC24 series), and 32-bit (PIC32 series) microcontrollers based on the MIPS architecture. They are characterized by low power consumption, a large number of integrated analog peripherals, and a comprehensive development ecosystem (MPLAB X IDE, Harmony Framework).

MSP430 (Texas Instruments) – Ultra-low-power 16-bit microcontrollers dedicated to battery-powered and measurement applications. They feature extremely fast wake-up times (<6 μs) and specialized analog blocks (such as operational amplifiers and ADCs). They are ideal for portable medical devices and smart energy metering solutions.

RISC-V – A modern, open 32-bit and 64-bit architecture that is rapidly gaining traction in the embedded market. Chips like the SiFive FE310 and ESP32-C6 (featuring Wi-Fi 6 and Thread support) offer high implementation flexibility and no licensing fees. RISC-V is becoming increasingly important in IoT, automotive, and sectors where complete supply chain transparency is required.