Top Embedded Systems Interview Questions and Answers 2025

Top Embedded Systems Interview Questions for 2024

1. What is the startup code?

It is a code that is called before the execution of the main function. It creates a platform for an application to run. It is called an assembly language.

2. What is the Semaphore?

It is a variable that is non-negative and can be shared between threads. It solves the critical selection problem and achieves synchronization in the processes.

3. What are the 2 types of Semaphore?

The 2 semaphores are Binary Semaphore and Counting Semaphore.

4. What is the full form of ISR?

ISR means Interrupt Service Routines. It is used when an interruption occurs. These procedures are stored at a memory location in the software.

5. When do we use a volatile keyword?

When a compiler changes its behavior unexpectedly after optimization, a volatile keyword is used.

6. What are the advantages of an Embedded system?

Some advantages of embedded systems are

• It is reliable
• It is inexpensive and small in size
• It ensures mass production
• Its operations are fast and require low power
• It improves product quality

7. What are the disadvantages of Embedded Systems?

• It is hard to maintain because of its use and throw nature
• It does not improve the technology
• It uses less power if it is battery operated
• Backup of embedded files is hard to take

8. What is an embedded system?

It is a hardware system that software designed to perform a specific specialized function or task. It can be a complete system or belong to a large system.

9. List the components of an embedded system.

There are 3 components of an embedded system

• Hardware
• Software
• Operating system

These components are further divided into

• Processor
• Memory
• Timers counters
• Communication ports
• Output
• Input

10. State the difference between thread and process.

A process is a program under execution running in separate memory spaces, whereas a thread is a segment of a process that shares information with other threads while containing its registers, counters, etc.

11. What is interrupt latency?

It is the time taken by ISR to respond to an interruption. Less latency means a faster response to the interrupting event.

12. When does a segmentation fault occur?

When a program instruction tries to access the prohibited memory address, a segmentation fault occurs. It sometimes leads to crashes in the programs.

13. Can a variable be volatile and const both?

Yes. Const keyword is used when a variable’s value should not change. But interrupts can still change the value.

14. What is a RISC architecture?

RISC architecture means Reduced instruction set computer architecture. It is a type of microprocessor architecture utilizing a small and highly optimized set of instructions to compute tasks in the least amount of time.

15. What is a reentrant function?

When a function can be interrupted during execution and can be called again safely, it is a reentrant function. The function resumes from the same point where it was left.

16. Which loop is better?

Countdown to zero loop is better than count up loops. This ensures the optimization of comparison to zero during loop termination.

17. What is the watchdog timer?

It is a part of the hardware that detects malfunctioning or anomalies in the software of the computer. It prevents the system from dangerous situations by detecting the faults in advance.

18. What is a Null pointer?

A Null pointer does not point to any valid memory location. It ensures that no pointer should be used to modify as it is invalid. It is addressed as NULL.

19. What is the syntax for a null pointer?

Data_type *pointer_name = NULL;

20. What does “const int x;” mean?

It means the variable is a read-only constant integer.

21. Which statement is faster ++I or i+1?

++i is faster because it uses single machine instruction, but i+1 requires loading. 

22. How can the errors in segmentation fault be avoided?

The Errors can be avoided in the following ways  

• Initializing pointer properly
• Minimizing the use of pointers
• Troubleshooting

23. Can printf() be used inside ISR?

No, it cannot be used in ISR because printf() is a non-reentrant and thread-safe function.

24. Can we pass or return a value or a parameter to ISR?

This is not possible because ISR does not allow anything to pass or return from it.

25. Why does interrupt latency happen?

It happens because

• The signal synchronization with the CPU depends on the hardware of the processor. It can take up to 3 CPU cycles for a signal to reach the processor.
• After the execution of an instruction, it takes some extra CPU cycles to refill the pipeline again with the instructions. This leads to latency.

26. How can you reduce interrupt latency?

Interrupt latency can be reduced by shortening the ISR routines.

27. How can you avoid a character pointer from pointing to a different address?

Since constant protects a pointer from modifications, The pointer should be defined as a constant character pointer.

28. What is a memory leak?

When the developers create objects or use the memory to help memory and then forget to free it before completing the program, a memory leak occurs. This leads to reduced memory availability and often crashes of the application.

29. What are the errors in an Embedded System?

Some common errors are

• Data connection malfunctioning
• Address line malfunctioning
• Inaccessible memory location
• Faulty control signals
• Faults in memory devices

30. How can you avoid a memory leak?

A Memory leak can be avoided by freeing the objects or pointers when no longer in use.

31. List some live examples of embedded systems use.

Embedded Systems are widely used in

• Identifying the speed of vehicles on a highway and intimating the authorities.
• Finding the accurate location of a vehicle by using GPS.
• The Automation system in houses with the help of android-operated remotes.

32. Explain a Microcontroller.

A Microcontroller also called an embedded controller, is a system inserted in a device to control the functioning of a product.

33. How can you swap 2 variables?

2 variables can be swapped in the following ways

• Using extra memory space
• Using arithmetic operators
• Using Bitwise operators
• Using One-Liner Bitwise operators
• Using One-Liner Arithmetic operators

34. Explain Automotive Embedded System.

Automotive Embedded System is a computer system designed for electronic devices that controls the mechanism of data and devices.

35. What is an Embedded C?

Embedded C is a part of the C programming language. It develops applications that are based on microcontrollers like Cameras, WiFi, etc.

36. List the 4 levels of testing in Embedded Systems.

The 4 levels of testing are

1. Unit testing
2. Integration testing
3. System testing
4. User acceptance testing

37. What are the different types of Buses used by Embedded Systems?

• Memory Bus

It is related to the memory-connected processor.

• Multiplexed Bus

It reads and writes in memory.

• De-multiplexed Bus

It contains 2 wires in the same bus. One has the address, and the other contains the data.

• Input/Output Bus

It multiplexes the same input and output signals by using multiplexing techniques.

FAQs

1. What are the 5 characteristics of Embedded Systems?

Characteristics of Embedded Systems

• Sole Functioning 

It usually performs a single specialized function repeatedly.

• Constraints

All computing systems on Embedded Systems have tight constraints.

• Real-Time

The embedded systems react to the system’s environment changes And bring quick results.

• Memory

Since the software is embedded in ROM, it has a memory and does not need any other secondary memory in the computer.

• Processor 

It must be based on a microprocessor or a microcontroller.

2. What are the types of Embedded Systems?

Embedded systems are classified on 2 factors

1. Based on performance and functional requirements

It is further divided into 4 types

• Real-time embedded systems
• Standalone embedded systems
• Networked embedded systems
• Mobile embedded systems

2. Based on the performance of microcontrollers

It is divided into 3 types

• Small-scale embedded systems
• Medium-scale embedded systems
• Complex embedded systems

3. Which software is used for Embedded Systems?

In most cases, embedded systems use basic embedded system software like C, C++, ADA, etc. The Specialized systems use operating systems such as Windows CE, LINUX, TreadX, Nucleus RTOS, OSE, etc.

4. What are Embedded Tools?

• Text editor
• Compiler
• Assembler
• Debugger
• Linker
• Emulator
• Integrated development environment (A software that provides necessary tools in a single package)

Important questions regarding Embedded Systems have been listed above. Practice and understand these to have deep knowledge about the types of questions that can be asked during the interview.

Conclusion

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