The real-time requirements of embedded systems are one of the key factors for their successful operation. Real-time requirements involve ensuring that the system can respond and perform tasks within a predetermined time. This article will discuss how to deal with the real-time requirements of embedded systems and illustrate it with specific cases and parameters.
1. Classification of real-time requirements
Before dealing with the real-time requirements of embedded systems, it is first necessary to understand the classification of these requirements:
Hard Real-Time Systems: These systems require tasks to be completed within a specified time. For example, flight control systems on airplanes must operate within strict time constraints, otherwise catastrophic consequences may result.
Soft Real-Time Systems: These systems are more flexible in the timing of tasks, but still need to be completed within a reasonable time. Video streaming is an example where a slight delay may be acceptable, but too much delay will degrade the user experience.
2. Processing of hard real-time systems
For hard real-time systems, real-time requirements are critical. Here are some ways to handle the real-time requirements of hard real-time systems:
Task priority assignment: Assign tasks to different priorities to ensure that critical tasks are executed within the scheduled time.
Task Scheduling Algorithm: Use an appropriate task scheduling algorithm such as Shortest Job First (SJF) or Earliest Deadline First (EDF) to maximize time requirements.
Hardware support: Use specialized hardware, such as a real-time operating system or coprocessor, to improve task response times.
3. Processing of soft real-time systems
For soft real-time systems, the real-time requirements are relatively flexible, but still need to be processed. Here are some ways to handle the real-time requirements of soft real-time systems:
Task Optimization: Optimize a task's algorithm to reduce execution time and thus better meet time constraints.
Buffering and Prediction: Use buffers to handle bursts of load while predicting system load to better prioritize tasks.
Resource management: Ensure reasonable allocation of system resources to avoid excessive competition, resulting in tasks not being completed on time.
Case Study: Automotive Anti-Lock Braking System (ABS)
Let’s use a car’s anti-lock braking system (ABS) as an example of how to handle real-time requirements.
Hard real-time requirements: ABS must quickly adjust brake pressure when the wheels are about to lock. This is a hard real-time requirement, as delays can cause the vehicle to lose control.
Task priority: The ABS system divides braking tasks into different priorities. With hardware support, the highest priority task (preventing wheel lock) has the shortest response time.
Real-time operating system: ABS systems usually run on a real-time operating system to ensure that tasks can be executed on time.
In this case, the ABS system uses a variety of methods to meet its hard real-time requirements and ensure that the vehicle remains safe during emergency situations.
In summary, the real-time requirements of embedded systems can be met through appropriate task allocation, scheduling algorithms and hardware support. Different types of systems and applications may require different methods to ensure tasks are completed within time constraints. Therefore, understanding and handling real-time requirements is an important part of embedded system design.
1. Classification of real-time requirements
Before dealing with the real-time requirements of embedded systems, it is first necessary to understand the classification of these requirements:
Hard Real-Time Systems: These systems require tasks to be completed within a specified time. For example, flight control systems on airplanes must operate within strict time constraints, otherwise catastrophic consequences may result.
Soft Real-Time Systems: These systems are more flexible in the timing of tasks, but still need to be completed within a reasonable time. Video streaming is an example where a slight delay may be acceptable, but too much delay will degrade the user experience.
2. Processing of hard real-time systems
For hard real-time systems, real-time requirements are critical. Here are some ways to handle the real-time requirements of hard real-time systems:
Task priority assignment: Assign tasks to different priorities to ensure that critical tasks are executed within the scheduled time.
Task Scheduling Algorithm: Use an appropriate task scheduling algorithm such as Shortest Job First (SJF) or Earliest Deadline First (EDF) to maximize time requirements.
Hardware support: Use specialized hardware, such as a real-time operating system or coprocessor, to improve task response times.
3. Processing of soft real-time systems
For soft real-time systems, the real-time requirements are relatively flexible, but still need to be processed. Here are some ways to handle the real-time requirements of soft real-time systems:
Task Optimization: Optimize a task's algorithm to reduce execution time and thus better meet time constraints.
Buffering and Prediction: Use buffers to handle bursts of load while predicting system load to better prioritize tasks.
Resource management: Ensure reasonable allocation of system resources to avoid excessive competition, resulting in tasks not being completed on time.
Case Study: Automotive Anti-Lock Braking System (ABS)
Let’s use a car’s anti-lock braking system (ABS) as an example of how to handle real-time requirements.
Hard real-time requirements: ABS must quickly adjust brake pressure when the wheels are about to lock. This is a hard real-time requirement, as delays can cause the vehicle to lose control.
Task priority: The ABS system divides braking tasks into different priorities. With hardware support, the highest priority task (preventing wheel lock) has the shortest response time.
Real-time operating system: ABS systems usually run on a real-time operating system to ensure that tasks can be executed on time.
In this case, the ABS system uses a variety of methods to meet its hard real-time requirements and ensure that the vehicle remains safe during emergency situations.
In summary, the real-time requirements of embedded systems can be met through appropriate task allocation, scheduling algorithms and hardware support. Different types of systems and applications may require different methods to ensure tasks are completed within time constraints. Therefore, understanding and handling real-time requirements is an important part of embedded system design.
