(SEM VI) THEORY EXAMINATION 2022-23 EMBEDDED SYSTEM

EMBEDDED SYSTEM (KOE-062)

Important Questions & Answers – Section-wise

SECTION A

(Attempt all questions – 2 × 10 = 20 marks)
 

a. Challenges in building an embedded system

Building an embedded system involves several challenges such as limited memory and processing power, strict real-time constraints, low power consumption requirements, and high reliability. Developers must ensure the system works continuously without failure, often in harsh environments, while keeping the cost low and performance optimized.

b. How SPI is different from other serial interfaces

SPI (Serial Peripheral Interface) is faster than interfaces like I2C or UART because it uses a separate clock line and full-duplex communication. It supports high data rates and simple hardware design but requires more pins, unlike I2C which uses fewer lines.

c. Functions of RTOS

A Real-Time Operating System manages task scheduling, memory management, inter-task communication, and timing constraints. It ensures tasks are executed within deadlines, which is critical for time-sensitive embedded applications like medical devices and industrial control systems.

d. Phases of Embedded Development Life Cycle (EDLC)

The phases include requirement analysis, system design, hardware and software co-design, implementation, testing and debugging, deployment, and maintenance. Each phase ensures reliability and correctness of the embedded product.

e. State machine model

A state machine model represents a system using states, events, and transitions. It helps in designing control-based embedded applications like washing machines, traffic lights, and elevators.

f. Different states of a thread

A thread can exist in states such as new, ready, running, waiting, blocked, and terminated. These states define the execution lifecycle of a task in an RTOS.

g. Remote Procedure Call (RPC)

RPC allows a program to execute a procedure on another system as if it were a local call. It simplifies communication in distributed embedded systems.

h. Sensors and Actuators

Sensors convert physical quantities like temperature or pressure into electrical signals, while actuators convert electrical signals into physical action such as motion or heat.

i. Watchdog timer

A watchdog timer resets the system if the software fails or enters an infinite loop. It improves system reliability and fault recovery.

j. Shared memory

Shared memory allows multiple tasks or processes to access the same memory space for fast data exchange, but it requires synchronization mechanisms to avoid conflicts.

SECTION B

(Attempt any THREE – 10 × 3 = 30 marks)

Q2(a) Characteristics of Embedded Systems

Embedded systems are application-specific, real-time oriented, resource-constrained, and highly reliable. They often operate continuously with minimal user interaction and are optimized for performance, power efficiency, and cost.

Q2(b) Semaphores, Pipes, and Shared Memory in RTOS

Semaphores are synchronization tools used to control access to shared resources. Pipes provide unidirectional communication between tasks, while shared memory allows fast data exchange but requires careful synchronization.

Q2(c) Communication strategies for embedded systems

Embedded systems use communication methods like serial communication (UART, SPI, I2C), parallel communication, network-based protocols (CAN, Ethernet), and wireless communication depending on application requirements.

Q2(d) Washing machine application (concept explanation)

A washing machine uses sensors to detect water level, temperature, and load. A controller processes these inputs and controls actuators such as motor and valves. The system operates using a state machine model for different wash cycles.

Q2(e) Memory management and DMA

Memory management ensures efficient allocation of RAM and ROM. DMA (Direct Memory Access) allows peripherals to transfer data directly to memory without CPU involvement, improving performance.

SECTION C

(Attempt ONE part from each question)

Q3(a) Oscillator unit and Real Time Clock

The oscillator generates clock signals required for CPU operation. The Real-Time Clock (RTC) keeps track of real-world time and date, even when the system is powered off.

Q3(b) Serial bus communication protocols

Protocols like SPI, I2C, and UART enable communication between embedded components. They are widely used in networking embedded devices due to simplicity and low cost.

Q4(a) Product life-cycle of embedded products

The product life cycle includes introduction, growth, maturity, and decline stages. Each stage affects cost, demand, and design updates.

Q4(b) Edge-triggered vs Level-triggered interrupts

Edge-triggered interrupts respond to signal changes, while level-triggered interrupts respond as long as the signal remains active. Edge-triggered interrupts are faster and preferred in real-time systems.

Q5(a) Task synchronization techniques

Synchronization techniques include semaphores, mutexes, event flags, and message queues. These prevent race conditions and ensure safe resource sharing.

Q5(b) Timing and clock in embedded systems

Timing ensures correct task execution order. Clocks synchronize CPU operations and peripherals, crucial for real-time applications.

Q6(a) ARM processor families

ARM families include ARM7 (low power), ARM9 (higher performance), Cortex-M (microcontrollers), Cortex-A (applications), and Cortex-R (real-time systems), each designed for specific needs.

Q6(b) Role of RAM and ROM

ROM stores firmware permanently, while RAM stores temporary data during execution. Both are essential for embedded operation.

Q7(a) Issues of RTOS

RTOS issues include priority inversion, deadlock, limited memory, and timing unpredictability if not designed properly.

Q7(b) SPI and I2C

SPI is a high-speed full-duplex protocol using multiple lines, while I2C uses only two lines and supports multiple devices on the same bus.