Embedded System Interview Questions With Answers

I was involved few times in the interviews of students applying for an internship. In my department we’re doing only embedded software/firmware, not hardware, however we’re in close contact with hardware guys to align interfaces. It looks like you are looking for an EE who knows how to write code. I would have difficulty answering your questions, despite 40 years experience && writing many device drivers and being mentored by top EEs. Obviously, your questions are based on your specific domain. This question can help the interviewer determine if you have the skills necessary to succeed in this role.

This exists in C because it allows the compiler to potentially produce more optimal code than an if-then-else sequence. Given that performance is normally an issue in embedded systems, knowledge and use of this construct is important. Basic knowledge of the #define directive as used in macros.

It refers to a specific function that calls to them any time before given the final result. Suppose a programmer needs to pass one value to one function to another. There has one very common approach to passing this value through a parameter of that specific function. We can now pass one of the copies of that require value as a variable or an object reference or memory reference where that variable value has been stored.

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Other queries are for assessing an applicant’s knowledge of embedded systems. Embedded C is a set of language extensions for the C programming language specified by the C Standards Committee. It is generally used to address commonality issues that exist between C extensions for different embedded systems.

It executes pre-processing of the High-Level Language . It is the first step of the language processing system. The main tasks of a pre-processor are comments removing, the inclusion of files and expansion of macros. The applications for which the embedded systems are designed to require no human intervention.

Here I have tried to create some collection of “embedded system interview questions with answers” that might ask by your interviewer. These embedded system questions not only for fresher but also good for the experienced person. This article is mainly focused embedded system meaning on the most repeatedly asked embedded system interview questions. If you are looking for “embedded system interview questions” or “simple questions on embedded systems”, then you at the right place. Yes, a variable can be both constant and volatile in C.

Thus, it is clearer, and penalty free to spell out how you are calculating the number of seconds in a year, rather than actually doing the calculation yourself. Loop unrolling is a compiler optimization that reduces the frequency of branches and loop maintenance instructions. It enables other optimizations and increases the parallelism degree in the loop body given the increase of its operations. It is easily applied to sequential array processing loops where the number of iterations is known prior to the execution of the loop. JFET stands for the junction-gate field-effect transistor.

Volatile

It can cause serious issues as reduces the performance of the computer by reducing the amount of available memory which leads to system slowdown due to thrashing. Semaphore is simply a variable that is non-negative and shared between threads. This variable is used to solve the critical section problem and to achieve process synchronization in the multiprocessing environment. https://globalcloudteam.com/ Another thing to note is an important issue that arises from this bad practice is that you perform the inclusion process with preprocessor text replacement in mind. Examples could be the use of virtual drivers in the case of Network simulators, also the support of virtual device drivers in case a user runs an additional OS in a virtual box kind of software.

Static global variables and functions are also possible in C++. They are mainly used to limit the scope of a variable or function to a file. Static variables are allocated memory in the data segment, not the stack segment. It is not possible to pass any parameter and return a value from the ISR. The ISR returns nothing and does not allow passing any parameter.

• Hope these embedded systems interview questions and answers will help you answer your interviews confidently and with better preparedness.
• It handles the rest of the start-up as well as input/output requests from software, translating them into data-processing instructions for the central processing unit.
• This is done deliberately to prevent any tampering or removal as it is critical for the device to run and can cause serious consequences if removed.
• It is the amount of time that elapses between the arrival of an external interrupt and the processing of the interrupt.

When answering this question, think of a skill or quality that you have that others may not. Try to choose something that is relevant to the job description. From my own experience the interviews get increasingly difficult as you apply for more senior positions, which also makes logical sense. Entry levels jobs are mostly based on coding and basic firmware theory concepts. For more senior positions you can expect some deep design questions.

Software Engineer Interview Questions

„volatile” is used to prevent the compiler to optimize any variable. Embedded software engineers are in high demand, with thousands of contract and permanent positions open across the United States. As a result, professionals with the right mix of technical and soft skills have every chance of landing their dream job — if you’re well prepared for your interview. Java is used in an embedded system for sophisticated and non-hard real-time tasks. Java has a set of standard libraries, so the functionality rewriting is not needed.

You need to be able to show that your skills and abilities can get the job done better than anyone else. F) ISR tells the processor or controller what to do when the interrupt occurs. 2) A kind of memory that retains data in the absence of a power supply. Request and the first instruction of the interrupt handler.

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Other languages used are JavaScript and Python for microcontrollers. Some Pre-processors Are Only Capable Of Performing Relatively Simple Textual Substitutions And Macro Expansions, while others have the power of full-fledged programming languages. 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.

Stack Memory

In Embedded C, ISR stands for Interrupt Service Routines. These are the procedures stored at specific memory addresses and called when a certain type of interrupt occurs. The occurrence of segmentation fault error is the reason to generate stack overflow error in C. The volatile keyword is mainly used when we have to deal with GPIO, interrupt or flag Register directly. It is also used with a global variable or buffer shared between the threads.

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The buses are data, bus, address bus and control bus. The purpose of the segment register is to hold the base address of the memory where a particular segment begins. There are different types of segment registers to perform various functions. They are code segment , data segment , stack segment and extra segment . This question can help the interviewer understand how you approach your work and what steps you take to complete it.

Use your answer to highlight some of the most important skills for an embedded systems engineer and explain why they are so important. The right Embedded Software Engineer has a strong knowledge of both software development and electronics. Their multifaceted skill set is defined by logical thinking and analytical abilities, programming skills in languages like C++ and strong organizational and writing abilities. Combined with their education and work experience, the ideal hire for this role has strong communication skills and is apt at providing support and helping people resolve issues. ARM processors are used for executing a small number of instructions at higher speeds by removing unnecessary instructions. They are used extensively along with embedded systems to reduce complexity, increase speed due to its reduced instruction set and decrease the power consumption.

How Can You Protect A Character Pointer By Some Accidental Modification With The Pointer Address?

This question can give the interviewer insight into how you approach challenges and solve problems. Your answer should show that you are willing to put in the time and effort needed to find a solution. Explain about forwarding Reference available in C programming language. Actually, the size of the char and int, not possible to define, as it always depends on the specific operating system or define firmware.

If you don’t have any experience with a specific language, consider highlighting another skill or attribute that makes you qualified for the job. To help you prepare for your interview, we’ve compiled a list of common embedded system engineer interview questions and answers. Memory Fragmentation is an issue that arises while using dynamic memory allocation. When we keep allocating and releasing memory spaces over time, in the end, we will get non-contiguous memory blocks that are free, and our in-use variables are scattered everywhere in the RAM. This can potentially lead to dynamic memory allocation failure.

Sometimes it creates hidden issues and can because of memory leak. In C language, the stack overflow error may occur if the program tries to access the memory beyond its available maximum limit. For example, the stack overflow error may occur if a pointer exceeds the stack limitations . It is an extension of C programming language that is used to develop micro-controller based applications.

No right answer, but it helps to identify their mindset and experience. In my experience, people that are technically very good, does not perform well in an interview. Getting a person to tell you what exites then and what they feel passioate about is a good approach, then dig deeper and deeper into that to evalute their skill and ability. Often, people that interview well becomes the bad apple in the team. This once again is not remembering the topology and calculation formulas for a specific type of opamp or filter or current source.

The functionality doesn’t need to be fixed but it has to be defined by the application higher-level. So, you can use a call back function that points to nothing. And in the application code, the user will write the interrupt handler function’s code and set the timer call back to point to this handler routine. So, whenever an interrupt is fired, the ISR will call the call back function which points to the user handler code and it’ll get executed. Where possible, it is best to avoid using char and short as local variables.

The const type qualifier declares an object to be unmodifiable. The watchdog timer is a timing device with a predefined time interval. During that interval, some event may occur or else the device generates a time out signal. It is used to reset to the original state whenever some inappropriate events take place which can result in system malfunction.

It could be in the same interview or you can have separate interviews focused on either coding or theory or design. I believe that the above mentioned embedded system interview questions are helpful. Here, I have mentioned some unsolved embedded system interview questions for you. The Cortex-M processors have very low interrupt latency. In the below table, I have mentioned, Interrupt latency of Cortex-M processors with zero wait state memory systems. Machine Code is the language of the computer rather than the programmer.

An interrupt latency is a latency that occurs while handling the interrupts. It is the amount of time that elapses between the arrival of an external interrupt and the processing of the interrupt. Some automated tools for testing embedded systems are Parasoft, Tessy, TestPlant, and KlocWork.

It is based on a program counter that starts from an initial value and counts down to zero. If the system gets disabled or hanged the timer starts working. An embedded system can be considered as a combination of both software and hardware that is designed for a particular function. It can be independent or attached to another system to increase its functionality.