How would you explain firmware to someone in our organization who doesn't have a technical background?

"Firmware is just another piece of software much like the programs you use every day. The difference being is that it is placed in hardware that contains permanent or non-volatile memory. The purpose of firmware is to provide a set of instructions used by an electronic device such as a computer, phone, or just about any other modern appliance. Without firmware, you and I or other software programs could not interact with the device, nor would it function properly."

This is a general or opening question which the interviewer will ask to begin the conversation, learn more about you, and uncover information that they can use throughout the interview. This provides a great opportunity to direct the conversation toward subject areas that you are familiar with and can easily discuss. When answering this question, be sure to use simple, easy-to-understand, and non-technical language and keep your answer brief and to the point.

Assuming that I have no technical background, please describe how firmware communicates with electronic devices.

"Firmware can be thought of as the permanent instructions an electronic device needs to start up and begin operating. Another key component of most electronic devices is a central processing unit, or CPU, which is the brain of the device. These two components communicate using computer code over an electronic circuit for the device to function properly. When the device powers up, the CPU sends a message to the firmware asking for its initial instructions. It then executes those instructions, which begins the operation of the device and sets up the parameters the device will use to function."

The purpose of this question is to demonstrate to the interviewer how you would communicate with individuals from other departments in their organization who are stakeholders in the projects you will be assigned. Firmware engineers frequently have to communicate with stakeholders from outside of their organization when discussing a project. Doing this using simple, easy-to-understand language will convince the interviewer that you are a team player and will fit well into the organization.

How can you reduce the amount of memory required in an embedded system?

"There are several different techniques you can use to reduce the amount of memory required by an embedded system. Some of these include factoring your code, only returning values when they are necessary, making a large number of calls to a small function as opposed to a small number of calls to a larger function, and using as many local variables as you can, reducing the number of system calls and memory usage. All of these techniques work, so I use the ones that are most applicable to the function of the device and the type of code I am writing."

Organizations hire employees for one of three reasons: to help them make money, save money, or save time. During an interview, you will be asked how you will accomplish this for the organization. Having creative ideas to accomplish some of these objectives will distinguish you from other candidates and convince the hiring manager to bring you on board. Before the interview, you should research the organization to understand its challenges and have a few ideas about how your work can help them overcome these.

Can you describe the steps required to create a firmware architecture?

"Creating any firmware architecture usually includes several fundamental steps. The basic ones are identifying the requirements, separating the firmware architecture from the system design, defining the time management parameters, testing the firmware, and finally, customizing the firmware for different types or versions of the device. Within each phase are individual steps that vary depending on the type of firmware being designed and its purpose. Firmware engineers are engaged in each phase to ensure that their design functions properly."

During the interview, the interviewer will ask you how you go about performing your job. These are known as operational questions. Interviewers use operational questions to confirm your qualifications and understand whether the work you do aligns with the processes and procedures used by their organization. They may also be interested in determining if you can improve their operations and make them more efficient.

What programming languages have you used to write firmware?

"Early in my career, most of the firmware I wrote was either in C or basic assembly code. This was sufficient because the code was then assembled into machine code which the hardware would access during start-up. However, with the proliferation of firmware into a wider variety of devices and appliances, I am now writing code using higher-level languages such as JavaScript, C++, Ruby, and Pearl. These are more efficient and enable me to create code specific to the device and its functions."

Contemporary firmware engineers must be familiar with a wide range of programming languages. Originally, firmware was written in low-level languages such as C or assembly code. However, many types of firmware are now written in higher-level languages such as JavaScript, Ruby, or Perl. While there is no right or wrong answer to this question, your research should indicate the types of programming languages the organization prefers. If possible, include these in your answer.

Do you know of any techniques which can be used to reduce the power requirements for an embedded system?

"There are several ways you can reduce the power requirements of an embedded system. One is to put the system into sleep mode and periodically refresh your operating system. If the system is simple or static, you can pause some of the nonessential functions, such as the timer or clock, when it is not needed. While these power reductions will be minimal, they will help increase the efficiency of the entire system."

During the interview, the interviewer may ask you to help them resolve a specific issue. This can take the form of a simple question or they may present you with a use case and ask you to resolve it. Most of these questions should be easy to address since they correspond with the experience and knowledge gained in your previous roles. However, if you do run across one that you are unfamiliar with, rather than solve the case, describe the steps you would take to resolve it, including gathering the information you currently don't have.

What are some of the common hardware and software errors or issues you run into when developing firmware?

"While there are a wide variety of issues I encounter in my work as a firmware engineer, some of the more common ones include damage to the system from static discharge or power surges and short circuits which impact the function of the software, firmware, or operating system. There are also common issues with component malfunctions, errors caused by users, and missing information due to memory address malfunctions. It is difficult to prevent some of these, but recognizing the cause of the errors enables me to quickly address and resolve them."

One of the critical tasks a firmware engineer performs is to debug their code and help resolve issues within the system. Some of these issues are caused by other devices and software beyond the firmware engineer's control. However, knowing about and being familiar with these will help you diagnose issues and assign the appropriate resources needed to resolve them.

How would you store data from a serial receiver line by using a specific data structure?

"When storing data from a receiver line, the first command I use stops the transmitter side from sending additional data. Commands that accomplished this include X/ON and X/OFF or RTS and CTS. I then set up a queue to store and prioritize the data. An alternative to this is using a ring-buffer. Both of these data structures establish a queue and are relatively easy to set up."

There are many different processes you can use as a firmware engineer. Some of these will be dependent on the type of system you design, while others may be a personal preference. In either case, when you were asked about specific processes, describe the steps using easy-to-understand, non-technical language. If you do not use the process you are being asked about, provide the interviewer with a reasonable alternative that can be used and is just as efficient.

What is one way you can test firmware before implementing it in the embedded system?

"One common way of testing firmware before it is installed in the embedded system is to use an emulation process. This involves simulating the firmware functions on a piece of test equipment that has an environment similar to that of the embedded system. The engineer recreates the functions, commands, and other performance features of the firmware. This allows them to debug and optimize the code before installing it."

This question requires you to have both technical and operational knowledge. You need to first understand how firmware is developed and the type of features you'll be testing for. You also need to understand the operations used to test the firmware and confirm that it will function once embedded into the system. Experienced firmware engineers should be able to easily answer this question.

Have you ever performed testing for middleware?

"I have a great deal of experience working with middleware. Since much of the code I write needs to interact with this layer, I get involved in the testing to assure that the two pieces of code are interacting appropriately. Some of the components I verify include the middleware's ability to provide authentication and messaging across the system."

Firmware engineers perform duties in addition to designing firmware and writing code. One of these duties is testing their software as well as other components of the system it interacts with. One of those components is called middleware. This question will test your knowledge of middleware and inform the interviewer of your experience interacting with this component and testing it to ensure that the code you write is compatible with it. Most firmware engineers have experience in this area.

Do you have experience working on computer kernels?

"Since I have worked for several computer manufacturers, I have a great deal of experience working with kernels. The firmware I create loads the kernel as one of the first steps in the start-up process for the computer. Once this is complete, the kernel manages the balance of the start-up process including memory, peripherals, and any I/O request from the operating system."

This question is specific to firmware engineers who work on computers rather than dedicated devices or appliances. This is because the kernel is a central processing unit or CPU component that interacts with the firmware when the device is powered on. It loads the code needed for the computer to complete the start-up and then function. If you work with computers and design firmware for them, then you have experience with kernels. Even if you haven't, you probably learned about them during your education and training. As with any question asking about a piece of technology, keep your answer brief and to the point and expect a follow-up question from the interviewer.

Can you define the term static keyword and describe its function?

"The term static keyword refers to the process of defining a function or variable. A static variable is stored in the computer's data memory rather than in the stack. Static keywords can only be initialized once, but they sustain their values out of the function. Their scope can be restricted to the file that was originally defined."

You'll be asked about many different terms and terminology during an interview for a firmware engineering job. This is an easy way for the interviewer to learn about your knowledge and experience. These are known as technical questions. Technical questions should be responded to directly and succinctly, using plain language. Be prepared for follow-up questions which the interviewer will use to collect additional information or explore the topic in more detail.

What are some of the uses of volatile keyword when writing code in the C programming language?

"The volatile keyword command can be used for several purposes. One is to turn off compiler optimizations, thereby removing loops that contain global variables. Another use of volatile keyword is to make the compiler aware that other processes may change variables during runtime. This comes in handy when you need to change volatile variables and update the values being used by execution commands. I have used volatile keyword commands for both of these purposes in my code."

By carefully listening to the interviewer's questions, you can gain a lot of information about their operations which you can use later in the interview. For example, this question indicates that the organization programs in C and use volatile keyword in their code. Knowing this helps you align your answers to this and any future questions with the type of work they do. Doing this will encourage the interviewer to begin to picture you in the role they are trying to fill. Carefully listening to the interviewer's questions will also help you provide the answer they are looking for.

What does the acronym EFI stand for, and how is it used in firmware engineering?

"The acronym EFI stands for extensible firmware interface. This is a new type of firmware being used in newly released computers. It allows the central processing unit to access the instructions in the embedded firmware with the subsequent control functions being provided by the bootloader. This technology enables the system to start faster and load the initial software programs designated by the user more efficiently."

As a firmware engineer, you frequently deal with specific acronyms used in your profession. This is common among most of the technical professions. While it is okay to use acronyms when speaking with colleagues or other people with technical backgrounds, you should avoid them or at least first define them when talking with someone from outside of your field. This applies even if the interviewer uses acronyms when questioning you.

What is flashing, and how is it used with firmware?

"Flashing is the process of updating firmware. For flashing to be possible, the firmware must be contained in a special type of memory storage device known as an EEPROM, or electronically programmable read-only memory. The purpose of flashing is to add new lines of code to the firmware to increase its functionality or adapt to changes in its environment. An example of this is when your phone is updated when you move between providers."

While most users or people with non-technical backgrounds may perceive firmware as permanent, as a firmware engineer, you know that some types of firmware can be updated or flashed. Being able to describe this and the benefits of flashing will help you validate your qualifications as a firmware engineer and demonstrate to the interviewer that you are fit for this role. Since this is a technical question, make sure to keep your answers brief and to the point, using non-technical, simple-to-understand language.

What is RISC architecture, and does it require firmware?

"RISC, which stands for reduced instruction set computer, is an architecture which uses a smaller optimized set of instructions to operate. This is in contrast to more complex and highly specialized sets of instructions found in other computers or processors. While this latter group of computers can perform more functions, the RISC architecture device is designed for a very specific functionality. These are common in dedicated devices or appliances."

When asked about a specific technical term, the interviewer seeks to understand how in-depth your knowledge is and whether you have the expertise required for this position. While it is impossible to be knowledgeable about all the technical terms used in any job, you should be familiar with most of them and be able to discuss them. If you aren't, admit this to the interviewer and then describe how you would go about learning about the technology.

Can you define middleware, and discuss how it is used?

"Middleware is the layer software that functions between the hardware layer and the application layer. Its purpose is to provide services to the applications while communicating with the hardware to gain access to the resources that the applications need to execute. Middleware typically consists of small sets of code with a very specific function. It is not as comprehensive as the operating system and has more dependencies than firmware."

Do not be surprised if the interviewer asks you about some other technology or component of the devices for which you will be writing firmware. As a firmware engineer, you need to be familiar with the operation of the complete device so that your code will interact with the other components effectively. Researching the organization and understanding the types of devices you will be working on will prepare you for these types of questions.

Can you describe some of the fundamental differences between firmware and other types of software?

"The primary difference between firmware and most other types of software is that the firmware is permanent and not accessible by users of the device. Most other types of software need to be loaded onto the device where they can be copied, changed, or removed by the users. Also, firmware typically has limited and dedicated purposes, whereas other software may be more general or able to execute multiple functions on different devices."

To someone who does not have a deep technical background or isn't directly involved in firmware development, firmware may seem like another piece of software. This is due to its dependence on coding and how it is executed using some type of processor. Interviewers may ask you this question because they generally don't understand these differences or want to see how you perceive them. Another purpose may be to test your communication skills and determine if you can describe complex technologies to individuals with little to no technical background.

What is one advantage of using C++ code for the Arduino platform?

"One of the advantages of using C++ code for the Arduino platform is that it enables you to use classes. This simplifies the programming and also makes the firmware perform better. It also allows for the use of virtual functions. An advantage of this is that it broadens the function of the firmware and allows it to handle many different types of operations. An example of this is the print base class. When invoked, it customizes the print methods to specific types of outputs."

This is an example of a very specific question you may be asked during an interview for a firmware engineer job. While you cannot be aware of all the interviewer's questions, you can narrow the field by reviewing the job description and learning more about the company's operations. This will provide you with specific information related to the work you will be doing and help you focus your preparation on the most likely questions you will be asked.

Are you familiar with a recursion function? If so, can you discuss when to use it and what happens when it is declared inline?

"I have employed recursion functions in some of the firmware I've written. I typically use these when I know there are only a few recursion calls in the program. When used inline, the recursion call will copy the complete definition of the function. This creates extra work for the compiler and slows down the performance of the firmware."

When writing firmware code, you will use a wide variety of functions and other lines of code. Interviewers are likely to ask you about some of these to test your knowledge and confirm that you have worked with firmware in your previous roles. While you can't be familiar with all the functions and lines of code used in firmware, you should be familiar with the most common ones and be able to describe them. If you are asked about something you are unfamiliar with, state that, then describe to the interviewer how you would research it.

What is a semaphore, and how is it used?

"A semaphore is a type of code used to enable multiple devices to access a resource or another device. One type of semaphore functions by only allowing one resource to access the device and excluding the second one. This is called a binary semaphore. The other type of semaphore enables multiple resources to access a device but limits the number of resources or time for the access. This type uses process synchronization which employs complex problem-solving."

During an interview for a firmware engineer's job, the interviewer may present you with a use case that requires you to resolve a problem or demonstrate how to program using certain values or tasks. They may ask you about a specific type of code used to execute a specific function. Most of these questions should be simple to answer due to your experience and knowledge. Some may be more obscure and address functions and code you don't commonly use. If you don't recognize the topic the interviewer is asking you about, admit this, and then describe how you would learn the code and include it in your firmware.

How are timers used in systems with embedded computing devices or appliances?

"One of the key elements of any system which uses embedded computing devices are the timers. These timers have several different functions depending on the system. Some of these include a real-time clock used by the system and software, initiating events, scheduling events, allowing for time delays between events, allowing for time-division multiplexing, and other time-related functions."

The interviewer will continue to ask you questions about components of embedded computer systems which interact with the firmware you develop throughout the interview. You can predict some of these questions by understanding the system the organization works with, develop, or use in their operations. This information is available in the job posting, on the organization's website, and from other sources.

What are some of the standard buses used in a computer system and what are they used for?

"There are several different types of buses used within computer systems and other devices for communication. Each of these has a specific function, and some of the common ones include PCI, ISA, and EISA. Other standard buses used for communication in computing devices are: Universal Serial Bus or USB, is used to communicate between a device's central processing unit and external devices, such as power supplies, speakers, and keyboards. - I2C is a serial bus that enables communication between multiple integrated circuits. - Controller Area Network or CAN bus, is specific to vehicles and allows various components of the vehicle's electronic control systems to communicate. "

As a firmware engineer, you focus on a very specific piece of hardware and programming code. However, since the firmware you develop interacts with various systems within a computer or electronic device, you need to be familiar with all the components and how they work. Being able to describe this to the interviewer will demonstrate your competency and proficiency in doing this work.

What is interrupt latency, and what steps can you take to reduce it?

"In the context of computing, interrupt latency is the time between when an interrupt call in the computer software is initiated and when it begins to perform the interrupt. Increased latency or delay may cause conflicts or performance issues within the system. The way I typically address this is to create some small ISR routines. These reduce the latency and make the system function faster and without conflicts."

As you can tell from the structure of this question, it is asking you about a technical feature or issue related to the type of systems you will be working on. Interviewers will ask you about technical issues that are important to them or challenges they are currently facing. Knowing how to resolve these types of issues will reinforce your qualifications for this role. You may be able to learn about the organization's current challenges by reviewing the job posting, exploring their website, or talking to current or former firmware engineers in their organization.

Can you define DMA, and discuss how it interfaces with devices containing firmware or microcontrollers?

"DMA, also known as direct memory access, is a feature built into computer systems which enable data to be transmitted directly to the system's memory bypassing circuits or the buses typically used to perform this function. This functions as a physical address, much like any other piece of memory. Devices can transmit data directly to the physical address, thereby saving time and freeing up resources for other processes."

As a firmware engineer, you need to be intimately familiar with the different types of devices and computer systems and how they interact with each other. Much of the code you program into firmware or microcontrollers will work with other parts of the computer system or external devices. Since this is a technical question, make sure to use easy-to-understand language and keep your answer brief and to the point. The interviewer will ask you additional questions if they need more information or explore the topic in more detail.

What are some of the differences between a microprocessor and a microcontroller?

"The difference between a bit microprocessor and microcontroller is small. Both of these are chips that contain software code used to control other devices. The main difference is that the function of a microprocessor is broad. It manages resources for other devices such as the input-output ports, memory, the operating system, and software programs. Microcontrollers have very specific functions related to the device within which they are embedded."

Often during an interview, the interviewer will return to questions they've previously asked. The purpose of these is to test your knowledge of the subject, correlate your answers, and ensure you respond to questions consistently throughout the interview. Providing honest answers to every question is an easy way to remain consistent. Keeping your answers brief and to the point will also help you to line up your answers to similar questions.

Does a computer operating system require firmware?

"All operating systems require a piece of firmware to boot or start. This bootstrap program is known as BIOS or the basic input/output system. The BIOS is contained in the computer's ROM or non-volatile memory. It contains what is known as the kernel of the operating system and loads this into the computer's random access memory when the power is turned on. It also manages other start-up activities to put the computer in a state in which the operator can use it."

As the interview progresses, the interviewer will continue to ask you questions about technology. These can range from very basic to very complex. As a firmware engineer, you should be well acquainted with the technology used in this profession and be able to easily discuss it and respond to the interviewer's questions. It is recommended that you take time to review fundamental technologies used in this job before the interview.

What is the programming language commonly used to write code for microcontrollers?

"When originally introduced, microcontrollers were typically programmed using assembly language. However, modern microcontrollers can be programmed in a wide variety of higher-level programming languages such as C++, Python, and JavaScript. The language used depends on the function of the microcontroller and the individual or organization that is creating it."

One of the responsibilities of firmware engineers is to create code for microcontrollers. Microcontrollers are similar to firmware in that they are embedded chips in electronic devices used to perform specific functions. However, they may be more complex and contain instructions requiring additional programming and specific programming languages. As a firmware engineer, you should be familiar with microcontrollers and be able to discuss how to write code for them.

How would you define embedded software design?

"Embedded software design is just another form of firmware. It is computer code written specifically for a piece of electronic equipment or household appliance. The code is embedded on a microchip and does not require power. When the device is switched on, it accesses the code in the firmware and uses it to perform the functions that it was designed for."

During an interview for a firmware engineer job, you will be asked a wide variety of questions. Many of these will be specific to the technology you use and the operations you perform in this role. When answering these types of questions, keep your answers brief and to the point, and use non-technical, easy-to-understand language. The interviewer is evaluating your communication skills and your knowledge when they ask these types of questions.

Can you describe the difference between a driver and a piece of firmware?

"Both firmware and device drivers have similar functions. However, they differ in several ways. They both provide instruction sets that allow hardware devices to function. However, firmware is standalone code specific to the device in which it resides. A driver, on the other hand, is code written to help two devices interface and is dependent on other programs, the device's operating system, or the hardware for which it is written."

This could function as a standalone question or a follow-up to a question the interviewer asked you earlier in the interview. Each time you answer a question, you should be prepared for follow-up questions that provide the interviewer with more information or to explore the topic in more detail. The question also asks you to compare two types of technology used in this profession. When doing so, you should define each technology and then discuss the differences between them.

Firmware Engineer Interview Questions

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1. How would you explain firmware to someone in our organization who doesn't have a technical background?
2. Assuming that I have no technical background, please describe how firmware communicates with electronic devices.
3. How can you reduce the amount of memory required in an embedded system?
4. Can you describe the steps required to create a firmware architecture?
5. What programming languages have you used to write firmware?
6. Do you know of any techniques which can be used to reduce the power requirements for an embedded system?
7. What are some of the common hardware and software errors or issues you run into when developing firmware?
8. How would you store data from a serial receiver line by using a specific data structure?
9. What is one way you can test firmware before implementing it in the embedded system?
10. Have you ever performed testing for middleware?
11. Do you have experience working on computer kernels?
12. Can you define the term static keyword and describe its function?
13. What are some of the uses of volatile keyword when writing code in the C programming language?
14. What does the acronym EFI stand for, and how is it used in firmware engineering?
15. What is flashing, and how is it used with firmware?
16. What is RISC architecture, and does it require firmware?
17. Can you define middleware, and discuss how it is used?
18. Can you describe some of the fundamental differences between firmware and other types of software?
19. What is one advantage of using C++ code for the Arduino platform?
20. Are you familiar with a recursion function? If so, can you discuss when to use it and what happens when it is declared inline?
21. What is a semaphore, and how is it used?
22. How are timers used in systems with embedded computing devices or appliances?
23. What are some of the standard buses used in a computer system and what are they used for?
24. What is interrupt latency, and what steps can you take to reduce it?
25. Can you define DMA, and discuss how it interfaces with devices containing firmware or microcontrollers?
26. What are some of the differences between a microprocessor and a microcontroller?
27. Does a computer operating system require firmware?
28. What is the programming language commonly used to write code for microcontrollers?
29. How would you define embedded software design?
30. Can you describe the difference between a driver and a piece of firmware?

Firmware Engineer Interview Questions

1. How would you explain firmware to someone in our organization who doesn't have a technical background?

2. Assuming that I have no technical background, please describe how firmware communicates with electronic devices.

3. How can you reduce the amount of memory required in an embedded system?

4. Can you describe the steps required to create a firmware architecture?

5. What programming languages have you used to write firmware?

6. Do you know of any techniques which can be used to reduce the power requirements for an embedded system?

7. What are some of the common hardware and software errors or issues you run into when developing firmware?

8. How would you store data from a serial receiver line by using a specific data structure?

9. What is one way you can test firmware before implementing it in the embedded system?

10. Have you ever performed testing for middleware?

11. Do you have experience working on computer kernels?

12. Can you define the term static keyword and describe its function?

13. What are some of the uses of volatile keyword when writing code in the C programming language?

14. What does the acronym EFI stand for, and how is it used in firmware engineering?

15. What is flashing, and how is it used with firmware?

16. What is RISC architecture, and does it require firmware?

17. Can you define middleware, and discuss how it is used?

18. Can you describe some of the fundamental differences between firmware and other types of software?

19. What is one advantage of using C++ code for the Arduino platform?

20. Are you familiar with a recursion function? If so, can you discuss when to use it and what happens when it is declared inline?

21. What is a semaphore, and how is it used?

22. How are timers used in systems with embedded computing devices or appliances?

23. What are some of the standard buses used in a computer system and what are they used for?

24. What is interrupt latency, and what steps can you take to reduce it?

25. Can you define DMA, and discuss how it interfaces with devices containing firmware or microcontrollers?

26. What are some of the differences between a microprocessor and a microcontroller?

27. Does a computer operating system require firmware?

28. What is the programming language commonly used to write code for microcontrollers?

29. How would you define embedded software design?

30. Can you describe the difference between a driver and a piece of firmware?