Hello EMBEDIN viewers,

  • Real-time systems require hardware components that can meet stringent timing constraints and ensure predictable behavior.
  • Key requirements:

1. Clock and Timer:

  • Real-time systems rely on accurate clocks and timers to schedule tasks and events.
  • Components need precise clock sources with low jitter to ensure accurate timing.

  • examples:

    • SysTick timers is the heart beat of RTOS as discussed in previous post for task switching.
    • RTC

2. Processor:

  • The processor should have sufficient processing power to execute tasks within their deadlines.
  • Real-time systems often require deterministic execution, so processors with predictable instruction execution times and minimal
    interrupt latency are preferred.

  • examples:

    • non-real time capabilities: ARMv8A (aarch64)
    • real-time capabilities: ARMv7-M (arm32) and ARMv7-R (arm32)
    • Overview
    • ARMv7-R/R5

3. Memory:

  • Both volatile (RAM) and non-volatile (ROM, Flash) memory should have predictable access times to support real-time operations.
  • Memory access latency should be minimized to ensure timely data retrieval and storage.
  • examples: Flash, SRAM, DRAM

4. I/O Interfaces:

  • Hardware interfaces for input and output should have low latency and deterministic behavior.
  • This includes interfaces for communication with sensors, actuators, networks, and other peripherals.
  • examples: I2C, SPI, CAN, UART

5. Interrupt Handling:

  • Interrupt latency can significantly impact real-time system performance.
  • Hardware components should support fast and prioritized interrupt handling to minimize latency and ensure timely response to external events.
  • examples: emergency braking systems

6. Bus Architecture:

  • The system bus architecture should minimize contention and provide efficient data transfer between components.
  • Dedicated buses or high-speed interconnects can reduce communication latency and improve overall system performance.

  • examples:

7. Power Management:

  • Power management mechanisms should be designed to minimize energy consumption without compromising real-time performance.
  • Low-power states should be carefully managed to ensure timely wake-up and recovery.
  • examples: spacecraft to save power, generated from solar energy and batteries

8. Fault Tolerance:

  • Real-time systems often operate in mission-critical environments where system failures can have severe consequences.
  • Hardware components should incorporate fault-tolerant features such as redundancy, error detection, and error recovery mechanisms.

  • examples:

    • CRC checks on medical systems to handle patients data
    • Implement a redundant memory array with error correction codes and dynamic redundancy management for fault tolerance in space systems,
      ensuring reliability through robust voting logic and environmental hardening.

9. Temperature and Environmental Considerations:

  • Components should be designed to operate reliably across a range of environmental conditions, including temperature, humidity, and vibration.
  • Thermal management solutions may be necessary to prevent overheating and ensure consistent performance.
  • examples: satellite systems to protect the hardware components and payload

10. Testing and Verification:

  • Hardware components should undergo rigorous testing and verification to ensure they meet real-time requirements under various operating
    conditions.
  • This includes testing for timing accuracy, reliability, and compliance with relevant standards.
  • examples: medical systems

Overall, hardware components in real-time systems must be carefully selected and configured to meet stringent timing constraints, ensure deterministic behavior, and provide reliable operation in mission-critical applications. Next time, we shall start with a design problem on timers, stay tuned!

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