(SEM VI) THEORY EXAMINATION 2023-24 EMBEDDED SYSTEM

EMBEDDED SYSTEM – KOE062

Section-wise Important Questions & Ready Answers

SECTION A

(Attempt all – 2 marks each)

(a) Need of Watchdog Timer

A watchdog timer is used to enhance system reliability by resetting the embedded system when the software fails to execute properly. It detects software hangs, infinite loops, or crashes and ensures automatic recovery without human intervention.

(b) Temporal Requirements

Temporal requirements define timing constraints such as response time, deadlines, latency, and throughput. These ensure that tasks execute within specified time limits, which is critical in real-time embedded systems.

(c) Features of CAN (Controller Area Network)

CAN supports high-speed communication, message prioritization, multi-master architecture, error detection, fault confinement, and reliable real-time data exchange, commonly used in automotive systems.

(d) Limitations of Polling Technique

Polling wastes CPU time because the processor repeatedly checks device status even when no data is available. It also increases response time and reduces system efficiency in multitasking environments.

(e) Models Used in Embedded System Development

Common development models include the waterfall model, spiral model, V-model, and prototyping model. These guide systematic design, testing, and implementation of embedded systems.

(f) State Machine Model

A state machine model represents system behavior using states, transitions, events, and actions. It is useful for modeling control-oriented embedded applications.

(g) Preemptive vs Non-Preemptive Scheduling

In preemptive scheduling, a running task can be interrupted by a higher-priority task, while in non-preemptive scheduling, a task runs until completion or voluntary release of CPU.

(h) Thread and Process

A process is an independent program with its own memory space, whereas a thread is a lightweight execution unit within a process that shares memory and resources.

(i) Goals of Design Process

The design process aims to achieve correctness, reliability, performance, low power consumption, scalability, and cost-effectiveness while meeting functional and timing requirements.

(j) Input Parameters of Engine Control Unit (ECU)

ECU inputs include engine speed, throttle position, air temperature, oxygen level, crankshaft position, and coolant temperature to control fuel injection and ignition timing.

SECTION B

(Attempt any three – 10 marks each)

2(a) Design Process for Embedded System

The embedded system design process starts with requirement analysis, followed by system specification, hardware-software partitioning, architectural design, implementation, testing, validation, and maintenance. Each stage ensures functionality, timing accuracy, and reliability.

2(b) RS-232, RS-422, and RS-485 Protocols

RS-232 is a short-distance, point-to-point serial communication protocol. RS-422 supports longer distances with differential signaling, while RS-485 allows multi-point communication with higher noise immunity, widely used in industrial automation.

2(c) Embedded Design Life Cycle (EDLC)

EDLC includes concept development, feasibility study, system design, hardware and software implementation, integration, testing, deployment, and maintenance. It ensures structured development and quality assurance.

2(d) Inter-Process Communication and Context Switching

IPC enables data exchange between processes using mechanisms like semaphores, message queues, and shared memory. Context switching involves saving and restoring task states during multitasking.

2(e) Smart Card System Application

A smart card system consists of a microcontroller, memory, card reader, and application software. It is used in banking, identity verification, and access control due to its security and portability.

SECTION C

3(a) Direct Memory Access (DMA)

DMA allows peripherals to transfer data directly to memory without CPU intervention. This improves system performance by freeing the processor for other tasks. DMA architecture includes DMA controller, memory, and I/O devices.

3(b) Real Time Clock (RTC)

RTC maintains accurate time and date information even when the system is powered off. It is commonly used in scheduling, data logging, and time-stamped applications.

4(a) I/O Device Ports and Characteristics

I/O ports provide an interface between the processor and external devices. Their characteristics include addressability, data direction, speed, and control signals.

4(b) Device Drivers in Embedded Systems

Device drivers are software components that control hardware devices. Types include character drivers, block drivers, and network drivers, enabling hardware abstraction.

5(a) Embedded Design Life Cycle (Detailed)

EDLC objectives include reliability, reusability, maintainability, and performance. Phases involve requirement analysis, system design, implementation, verification, validation, and maintenance.

5(b) State Machine Model of Chocolate Vending Machine (ACVM)

The ACVM operates through states such as idle, selection, payment, dispensing, and return. Transitions occur based on events like coin insertion and button press.

6(a) RTOS Terminologies

Semaphores manage synchronization, mailboxes enable message passing, pipes support data streaming, and shared memory allows fast inter-task communication.

6(b) Interrupt Handling in RTOS and RTLinux

RTOS handles interrupts by prioritizing and scheduling tasks accordingly. RTLinux provides real-time extensions to Linux with deterministic response and low latency.

7(a) Engine Control Unit (ECU)

An ECU uses sensors, microcontroller, and actuators to control fuel injection, ignition, and emission systems. It improves engine efficiency and performance.

7(b) Washing Machine Embedded Application

A washing machine embedded system controls water level, temperature, motor speed, and cycle timing using sensors, controller, and actuators for automated operation.