Embedded Systems Lecture Notes

Introduction

• Welcome to the course on embedded systems.
• Today's lecture focuses on the differences between embedded systems and general-purpose systems.

What is an Embedded System?

• Definition: An embedded system is a microcontroller or microprocessor-based programmable system embedded within a larger system.
• Functionality: Takes inputs from the environment, processes information, and returns outputs to the environment.
• Sphere of Control: The parts of the larger system that are sensed and actuated by the embedded system.

Examples of Embedded Systems

• Everyday Devices:
  • Mobile phones with multiple communication systems and controllers.
  • Inkjet and color printers with embedded controllers.
  • Intelligent washing machines that adjust operations based on content.
• Automobiles:
  • Modern cars contain multiple embedded systems for brakes, cruise control, and locking systems.
• Aerospace:
  • Many airplanes rely on embedded systems for navigation and control.
• Warfare Technology:
  • Rocket launchers and other military technology uses embedded systems for operation.

Cyber-Physical Systems

• Definition: Systems where embedded controllers interact with physical environments (e.g., cars negotiating road conditions).
• Internet of Things (IoT): A network of embedded systems that communicate over the internet.

Components of an Embedded System

• Processing System: Typically a microcontroller or microprocessor.
• Sensors: Interact with the environment to gather data.
• Actuators: Affect the physical world based on the processed information.
• Analog-Digital Conversion: Necessary for interfacing with analog sensors and actuators.

Differences Between Embedded Systems and General-Purpose Systems

• Purpose: Embedded systems are usually for a single application, while general-purpose systems serve multiple applications.
• Constraints:
  • Cost: Must be low.
  • Power: Often battery-operated.
  • Real-time: Many systems require real-time processing capabilities.
  • Speed: Must often operate quickly.

Real-Time Systems

• Types:
  • Hard Real-Time Systems: Strict time constraints (e.g., nuclear power plant controls).
  • Soft Real-Time Systems: Time constraints are less strict; delays reduce quality of service but do not lead to catastrophic failures.

Design Challenges in Embedded Systems

• Cost: Must balance development costs and production costs.
• Power: Must be efficient, especially for battery-operated devices.
• Performance: Includes latency (time to complete a task) and throughput (the number of tasks completed in a time frame).
• Flexibility: Ability to adapt to new demands and technologies.

Hardware-Software Trade-Offs

• Design decisions involve determining which functions to implement in hardware versus software.
• Hardware Advantages: Faster performance, but may increase costs and physical size.
• Software Advantages: Greater flexibility, but potentially slower performance.
• Key Challenge: Designers must optimize the balance between hardware and software implementations for an effective embedded system.

Conclusion

• Understanding embedded systems involves recognizing their unique challenges and applications compared to general-purpose systems.
• The interplay between hardware and software design is critical in developing efficient embedded systems.