Microcontroller

Aka. MCU. A compact integrated circuit designed to control embedded systems.

Includes:

• CPU
• Memory
• I/O interfaces
• Timers and peripherals

Often implemented as a System-on-Chip (SoC)

Microcontrollers are widely used in IoT devices because they:

• consume very little power
• require few external components
• provide built-in I/O capabilities.

Microcontroller Architecture

Hardware Model

Describes the physical structure and electrical characteristics of the microcontroller, which includes:.

• Power supply requirements
• Clock system
• Bus architecture
• Memory types
• Bus timing
• Pin configuration

Programmer’s Model

Represents the microcontroller from the software developer’s perspective, which includes:

• Instruction set architecture
• Memory organization
• Register model
• ALU capabilities
• Interrupt handling
• Peripheral device access
• Resource management

Components

Microprocessor Unit

Aka. MPU. The central processing unit inside the microcontroller that executes instructions and controls system operations. Uses a specialized or scaled-down processor design. Often based on architectures like 8051, 8048, or 68HC11. Executes instructions and coordinates peripherals.

Memory Subsystems

IoT systems use Howard architecture to improve instruction execution efficiency.

Program Memory

Stores the executable instructions of the microcontroller program. Usually implemented as flash memory. Often read-only during program execution. May be read-protected for intellectual property protection.

Data Memory

Stores variables and temporary program data. Often implemented as RAM. Sometimes structured as a register file for faster access.

Peripheral Modules

Peripheral modules extend the functionality of the microcontroller by enabling interaction with external devices.

Examples:

• Timers and counters
• Analog-to-digital converters
• Communication interfaces
• Digital I/O ports

Peripherals act as interfaces between the processor bus and the external environment.

Communication Interfaces

Communication interfaces enable data exchange with external systems or networks.

Examples:

• UART
• SPI
• I²C
• Network interfaces

Supervisory Modules

Supervisory modules monitor system health and ensure correct processor operation.

Watchdog Timer

A watchdog timer resets the system if software becomes stuck in an infinite loop.

• Requires periodic reset by software
• If timeout occurs → system reset

Burnout Detection

Burnout detection monitors supply voltage and resets the microcontroller if power instability is detected.

Startup Delay

Delays processor execution after power-up until the system stabilizes.

Oscillator Delay

Ensures the system clock stabilizes before instruction execution begins.

Examples

PIC and AVR support many peripherals. AVR supports analog input/output. Intel 8051 is an older architecture with limited resources which uses 8-bit instruction set. ARM is a newer architecture with more powerful features and better performance, but it is more complex and consumes more power than PIC and AVR.