Essential Notes · Chapter 2.4 Embedded Systems and Software

2.4.1 Definition and Characteristics of Embedded Systems

Definition

An Embedded System is a dedicated computer system that is application-centric, based on computer technology, with customizable hardware and software, and meets strict requirements for functionality, reliability, cost, size, and power consumption in application systems.

In simple terms: an embedded system is not a general-purpose PC, but rather a computer system embedded in specific devices to perform dedicated tasks.

Main Characteristics

• • Specialization: Designed for specific applications.
• • Real-time: Must complete tasks within specified time limits.
• • Resource-constrained: Limited storage and computing capabilities.
• • High reliability: Typically operates in unattended, long-term stable scenarios.
• • Miniaturization and low power consumption: Adapted to the environment of embedded devices.

👉 Example: Baseband processors in smartphones, automotive ECUs, control chips in home appliances, industrial control systems.

2.4.2 Components of Embedded Systems

Embedded systems generally consist of embedded hardware + embedded software:

1. 1. Embedded Hardware

• • Processor: MCU, DSP, ARM, RISC-V.
• • Memory: ROM/Flash (stores programs), RAM (runs data).
• • Peripherals: Timers, I/O interfaces, sensors, communication modules.

2. Embedded Software

• • Firmware: Programmed into Flash/ROM, directly drives hardware.
• • Embedded Operating Systems (RTOS): Such as VxWorks, FreeRTOS, μC/OS-II.
• • Middleware and Applications: Protocol stacks (TCP/IP, Bluetooth), control logic, UI interfaces.

2.4.3 Embedded Operating Systems

Functions

• • Provides task management, memory management, and driver interfaces.
• • Ensures real-time performance and high reliability.

Characteristics

• • Occupies minimal resources, with a customizable kernel.
• • Supports real-time scheduling with predictable response times.
• • Manages multiple tasks and inter-task communication (semaphores, message queues).

Common Embedded Operating Systems

• • Commercial: VxWorks, QNX.
• • Open-source: FreeRTOS, RTEMS, Zephyr.
• • Specialized: Embedded Linux (powerful, suitable for complex applications).

2.4.4 Embedded Software Development

Development Process

1. 1. Requirement analysis (determine functionality, real-time, and reliability requirements).
2. 2. Hardware selection (MCU/DSP/ARM, memory configuration).
3. 3. System design (determine whether to use RTOS, task division).
4. 4. Software development (firmware, drivers, applications).
5. 5. Joint debugging and testing (hardware/software collaborative verification).
6. 6. System deployment and maintenance.

Typical Development Tools

• • Embedded C/C++ languages.
• • Cross-compilation toolchain (Cross Compiler).
• • JTAG debuggers, emulators.

2.4.5 Application Areas

• • Consumer Electronics: Smartphones, smart homes, wearable devices.
• • Automotive Electronics: ECUs, ADAS, in-car entertainment systems.
• • Industrial Control: CNC machine tools, robots, sensor networks.
• • Aerospace and Military: Flight control systems, navigation, radar.
• • Medical Devices: Heart rate monitors, ventilators.

2.4.6 Key Points for Architects to Focus On

• • Resource constraints: Need for memory optimization and low-power design.
• • Real-time: Task scheduling and interrupt latency must be predictable.
• • Reliability: Fault tolerance and redundancy design.
• • Security: Embedded devices are often IoT nodes, requiring attention to security measures.

Summary

1. 1. Embedded systems are dedicated, real-time, resource-constrained, and highly reliable computer systems.
2. 2. Composed of hardware (processors, memory, peripherals) and software (firmware, RTOS, applications).
3. 3. Embedded operating systems emphasize miniaturization, real-time performance, and customizability.
4. 4. Development requires specialized tools such as cross-compilation and hardware debugging.
5. 5. Widely applicable across consumer electronics, automotive, industrial, aerospace, and medical fields.