Top 10 Interview Questions & Answers for Embedded System Engineers

The way you perform in an interview will determine your role in the organization. An interview may last for a maximum of one hour, during which you have to showcase the skills and knowledge you acquired over the years. Read and understand the embedded systems interview questions below and ace your next interview.

10 Senior Embedded Software Engineer Interview Questions to Learn in 2023

Apart from your technical knowledge, you need to possess the confidence and good communication skill to win an interview. The below provided embedded system interview questions can help you to become interview ready.

• When is it necessary to utilise the volatile keyword? Give a thorough justification.

A volatile keyword can denote a specific variable with the conditional point of memory where that variable is mapped with another device in circumstances where a program is willing to use a particular parameter that belongs to other mapped devices. 

The stated variable can be easily modified from outside of that particular program, which is the key benefit of the same. Normally, the compiler defaults to performing additional optimisation for that particular program when we build any program. However, the compiler cannot make any further code optimisations in the case of volatile parameters.

• Describe ISR.

ISR stands for Interrupt Service Routines. These programs are stored in a specific memory area and launched in response to specific interrupts. 

The term "interrupt" describes the signal that tells the processor that an urgent situation needs to be handled immediately. To handle the high-priority event, the processor halts the usual program flow and executes the instructions in ISR. The program continues its regular flow when the ISR has been executed.

• Describe the C programming language's forwarding reference.

This is one of the embedded systems interview questions that are asked the most frequently. 

In the C programming language, a forward reference denotes when we intend to address or point to a smaller data type using a specific pointer of a larger data type.

• What are the specific differences between using the inline and macro functions?

Macro just assumes one of the symbolic representations whenever programming is involved, but it never aids in data type distinction, which is something we typically do. In contrast, it is simple to define various data types using inline functions.

• Can a static variable be declared in a header file?

Static variables are local to the block they are defined in and have a single initialisation, lasting until the end of the program. The definition is necessary for a declaration of static variables. 

It can be declared in the header file. But if we do so, each source file where the header is included will contain a private duplicate of the variable from the header file.

• What are the specifics of a soft and a hard real-time system?

Hard real-time have a strict deadline, never considering late delivery or response. If the system failed to deliver timely responses, it would be considered a failure.

However, a slight delay in responses is accepted in the instance of soft real-time. It focuses mainly on the delivery's performance and the product's quality. Other factors could be considered for slight delivery delays or deadline violations by a superior product.

• Recursive functions: What are they?

A code function known as a recursive function executes itself by referencing itself. Recursive operations can be straightforward or complex. They make it possible to write more effective code, for example, by listing or assembling collections of integers, strings, or other variables using a single repeated procedure.

• Explain a memory leak.

On a small embedded MCU, memory leaks are more likely to happen when there are lots of hardware interrupt calls, lots of nested subroutine calls, and big data arrays. As a result, the amount of memory required to process interrupt and subroutine calls increases to the point where they interfere with the data area.

• What common mistakes do embedded systems make?

Embedded system problems frequently include the following:

• Data lines not working
• Address line malfunctioning as a result of a circuit short
• Access to specific memory locations is lost
• Incorrect control signals
• Memory device damage
  

• Clearly define pass-by-value and pass-by-reference. How can we pass a single structure as the argument if we wish to?

Consider a situation when a programmer must transmit a value from one function to another. To pass this value through a parameter of that particular function, there is just one method that is quite popular. Now, one of the copies of the required value can be passed as a variable, object reference, or memory reference, depending on where the variable value is kept. 

The first method is regarded as passing by value, while the second pass is by reference. Supplying a parameter by value prevents changes from being reflected in the calling method, whereas passing a parameter by reference causes all changes to be reflected in the calling code.

Some Common C Interview Questions for Embedded Engineers

• Why do segmentation fault errors occur?
• A stack overflow issue in C is what?
• Why does C utilise a "volatile" keyboard?
• What do the terms "pre-decrement" and "post-decrement" mean?
• The default size for primitive kinds like Int, Char, and Float data types needs to be maintained – Justify.
• How does the utilisation of the location of a local variable cause less-than-ideal code?
• Describe the C programming language's forwarding Reference.

Skill-Lync with its expertise in providing technical education offers placement training to eligible students. We conduct mock interview and resume building session to make you interview-ready. 

Conclusion

Due to its simplicity, effectiveness, quick development time, and portability from one system to another, embedded C is the most often used language for creating embedded systems. It is crucial to managing hardware resources wisely and ethically because embedded systems have limitations on their CPU, memory, and other resources. 

There is a huge demand for embedded professionals who could take up challenging roles. You can use the above list of embedded engineer interview questions as a guide to start your interview preparation.