What is embedded?

Learn the embedded system concept and C++ constraints.

What is embedded?

An embedded system is a computer designed for a specific task, with limited memory and power. A washing machine, a car engine control unit, a smart watch are all embedded systems.

Embedded C++ programs typically run without an operating system (bare-metal) or on an RTOS (Real-Time Operating System). Memory is very tight; tools that use dynamic memory like std::vector are avoided. Hardware is accessed directly through memory-mapped I/O.

Constraints and tools

In embedded systems dynamic memory allocation is constrained; the heap is small or absent. Large data is kept static or on the stack. Exception handling is usually disabled (-fno-exceptions); exception tables take memory.

Hardware access happens through memory-mapped I/O: writing to a specific memory address changes a register. These addresses are read/written as volatile pointers; this prevents the compiler from skipping reads. An RTOS handles task scheduling; bare-metal programs manage their own loop.

Exercise Write an embedded-style message

In main write std::cout << "Embedded"; and end with return 0;.

Show example solution

#include <iostream>

int main() {
    std::cout << "Embedded";
    return 0;
}

Test yourself

What characterizes an embedded system?
```
// program running on a microcontroller
```
- Unlimited memory
- General-purpose operating system
- Designed for a specific task, constrained resources
- Always a powerful CPU
Show answer

Designed for a specific task, constrained resources — An embedded system is designed for a specific task with constrained resources.

Complete the main name

int ____(void) { /* embedded entry */ }

Show answer

int main(void) { /* embedded entry */ }

Match each concept to its role

RTOS

Real-time kernel
MMIO

Memory-mapped I/O
volatile

Hardware access
interrupt

Hardware interrupt

Next lesson: Memory-mapped I/O

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