Embedded Systems Interview Questions
The word embedded merely means that something is attached to another thing or system. An embedded system is just like a computer hardware system, but it has software embedded inside the system. It is mainly a part of a bigger system or an independent system. It is based on microprocessor and microcontroller in order to perform specific tasks. Example of an embedded system is a fire alarm. All the popular Embedded System interview questions and answers have been put together which will be handy if you want to crack an interview.
The three main components of an embedded system are
- Hardware Components
- Software Components
- RTOS (Real Time Operating System).
The first modern embedded system was known as Apollo Guidance Computer. It was developed by Charles Stark Draper in the year 1965 at the MIT Instrumentation Laboratory. These top embedded system questions and answers will be helpful in clearing job interviews and getting a promotion at work.
Key points about Embedded System
- It is a single functioned.
- It is mainly microprocessor based.
- It should have a memory and is generally embedded in ROM. It does not contain secondary memory.
- Embedded systems are attached to personal computers in order to increase performance.
- There are low chances of any damage in this system.
- Programming languages like C and C++ are commonly used in embedded systems.
Go through this specially curated list of expertly picked embedded interview questions to get guaranteed success with the embedded job interview.
Advantages of Embedded System
- It is customizable easily.
- Power consumption is low.
- Cost of the overall system is low.
- It can enhance performances.
- It uses fewer resources.
- They are always dedicated to a particular system, and so the performance is excellent.
- It can be managed easily.
- The size of the system is small but faster to load.
Most Frequently Asked Embedded Systems Interview Questions And Answers With Examples:
- What is an embedded system and why it is used?
- Explain the characteristics of embedded system?
- What are the different types of embedded systems?
- What are the advantages and disadvantages of embedded system?
- Explain the components of an embedded system?
- Explain the difference between a microcontroller and an embedded system?
- Explain the difference between microcontroller and microprocessor?
- What is DMA in an embedded system?
- How are macros different from functions?
- How do you reduce interrupt latency?
- What is the task of the pre-processor?
- What is the purpose of the segment register?
- What is the purpose of a watchdog timer?
- What is mutex in an embedded system?
- Why is java used in embedded systems?
- What is RTOS in an embedded system?
- What are the commonly found errors in embedded systems?
- What is the bus in a microcontroller?
- Explain the difference between testing and verification?
- How do malloc and calloc work?
The embedded system is an integrated hardware circuit system which is programmed to operate, organize and perform the singular or multiple tasks based on the application. The assembled units of the embedded system work together based on a set of program or rules which have been embedded into the microcontroller.
The Embedded systems come varied shapes and sizes. It varies from large multiple racked data storage systems to tiny or small modules like the personal MP3 players or cellular handsets.
Some of the significant characteristics of an embedded system are:
- It contains the processing engine
- The embedded systems are designed for a particular application,
- The embedded system includes a simple user interface like an automotive engine ignition.
- The embedded systems usually have a simple user interface and power limitations. Like some embedded system operate from batteries only
- The application software is mostly built-in the integrated system, and it is not selected by the user
- The applications for which the embedded systems are designed to require no human intervention.
The embedded system is based on the performance and functional requirements. The embedded system is divided into four major categories.
- Stand-alone embedded systems:- The autonomous embedded system does not require a host system like a computer, but it works all by itself independently. It receives input from the input ports either in digital form or analog form and transfers the data to give the resulting data through the connected device which is responsible for controlling the associated devices. Some examples of a stand-alone embedded system include mp3 players, digital cameras, video games, and temperature measurement systems.
- Real-time embedded systems:- This system requires an output in a particular time frame. It follows the time deadlines for the completion of the set tasks. The real-time application embedded systems are further classified into a soft real-time system and hard real-time system.
- Networked embedded system:- This type of embedded system is related to networks which can access the resources. It is connected through the LAN, WAN, or the internet. The connection can be wired or even wireless. The embedded system which is networked is the most popular today; wherein all the embedded devices are controlled by the web browser and protected by the protocols IP/TCP.
- Mobile Embedded Systems:- Mobile embedded systems are much more preferred than others. These are portable devices like mobile phones, digital cameras, wireless mp3 players, etc. the only limitation with this embedded system is that it has limited memory.
Note: Embedded systems uses are very general question in Embedded systems interview questions.
Advantages of the embedded systems
- They are easy for mass production
- It is highly reliable
- It has improved product quality
- The embedded systems use low power operation
- The embedded system operates very fast, and it is portable and small in size
Disadvantages of the embedded systems
- It has no room for technological improvements
- The embedded systems are hard to maintain
- It is complicated to take back up of the embedded files
- The embedded systems have less power supply durability if it is battery operated.
The components of an embedded system are mainly divided into three parts:
- Hardware Components:- The different hardware components of an embedded system includes a power supply, processor, memory, timer-counters, communication ports, input and output, and application specific circuits like temperature sensor or buzzer for the alert purpose.
- Software Components:- The different software components of an embedded system includes assembler, emulator, debugger and compiler.
- RTOS (Real Time Operating System):- The job of this system is to supervise the software components and gives a mechanism which allows a processor to run a process according to the schedule.
The difference between an embedded system and microcontroller are:
|1.||Embedded system is an electronic system.||The microcontroller is the heart of an embedded system, and it controls the operation.|
|2.||Embedded system looks after the whole process.||A microcontroller looks after specific tasks only.|
|3.||An embedded system consists of hardware and software components.||A microcontroller has CPU, RAM, and ROM which are a part of the embedded system.|
The difference between microprocessor and microcontroller are:
|1.||The microprocessor is the central part or heart of the computer system.||The microcontroller is the heart of an embedded system.|
|2.||Microprocessor chip does not have RAM, ROM I/O units and timer.||A single microcontroller chip has CPU, RAM, and ROM.|
|3.||There is no power system feature in a microprocessor.||Power saving feature is there in a microcontroller.|
|4.||A microprocessor system is complex and expensive.||The microcontroller system is inexpensive and straightforward.|
|5.||Microprocessor depends on technology, and so the system can run at a very high speed.||A microcontroller depends on its architecture, and hence the system can run up to 200 MHz.|
|6.||Microprocessor runs on the Von-Neumann architecture where data and program can be stored in the same memory.||The microcontroller runs on Harvard architecture, and so data and program memories are separate.|
|7.||The microprocessor is generally used in personal computers.||A microcontroller is used in washing machines and MP3 players.|
Note:- The embedded system market is continually increasing, so embedded system interview questions are essential.
In an embedded system, DMA stands for Direct Memory Access. It is a process that allows an input/output (I/O) device to send or receive data from the main memory. A chip known as the DMA controller (DMAC) manages the DMA process. Data is communicated between the peripheral device and system memory through the DMA channels.
Macros are different from functions in many ways like:
|1.||Macros are pre-processed.||Functions are compiled.|
|2.||The code length in macros always increases.||In functions, the length of the code does not change.|
|3.||Macros do have side effects.||Functions do not have any side effects.|
|4.||Compile errors cannot be checked in macros.||Compile errors can be checked in functions.|
|5.||Macros are generally useful when small codes appear a number of times.||Functions are useful when large codes appear a number of times.|
|6.||Type checking is not required for macros.||Type checking is required for functions.|
Interrupt latency can be reduced by making a short interrupt routine if interrupt priorities are not allowed by the hardware. In such a case interrupt routine which is started cannot be interrupted by another interrupt. It will be better to avoid disabling the interrupts in any method. In such a case the interrupt has to wait for the next one to be allowed.
Pre-processor is system software which can run on a computer's hardware and application. It executes pre-processing of the High-Level Language (HLL). 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 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 (CS), data segment (DS), stack segment (SS) and extra segment (ES).
It is a piece of hardware which is used for automatic detection of software anomalies. If such defects occur, then it resets the processor. This timer is mainly based on a counter which can count down from some initial value to zero.
Java is used in an embedded system for sophisticated and non-hard real-time tasks. It gives high performance and has small footprints. This reduces development time and errors. Java has a set of standard libraries, so the functionality rewriting is not needed. It provides excellent development productivity which is required in an embedded system.
The full-form of RTOS is a Real-Time Operating System. The primary purpose of an RTOS in an embedded system is to serve the real-time applications which can process the data without any kind of buffer delays. It also looks after the hardware complexities. RTOS is used in an embedded system because it can meet real-time deadlines and can efficiently manage complexities.
Note:- Some times interviewer can give you to make a standard report at the time of embedded system interview questions.
The standard errors that are found in an embedded system are:
- Stack overflow error :- Call stack has a limited amount of memory, and excessive memory usage in this stack can cause the failure. The memory of the call stack contains information of active subroutines in the program.
- Segmentation Fault :- A violation occurs in a program when there is an attempt to access a non-existing memory.
- Memory Leak :- This happens due to the incorrect management of memory allocation such that the memory that is no longer required is not released.
- Fragmentation or Memory corruption :- It happens because memory is altered without an explicit assignment.
It is a pathway to move the data rapidly through digital signals. There three different types of internal buses with are related to the processor. The buses are data, bus, address bus and control bus. All these together make up the system bus.
Both testing and verification are two different methods but these help in checking the application requirements and developments. The primary purpose of both is to provide a correct application — however, the difference between the two.
|1.||The process of testing is generally done after verification.||Verification is a process which is usually done before testing.|
|2.||Software testing is done by testers.||Process verification is done by a developer.|
|3.||The job of testing is to check the process for its functionality and requirements.||The main job of verification is to remove bugs and issues during development.|
- Malloc :- The primary function of malloc is to allocate memory at runtime. The size is taken in bytes, and correctly that much space is allocated in the memory.
- Calloc :- It is similar to malloc as it allocates memory at runtime which is defined in stdlib.h. The job of calloc is to take the number of elements, and each element size is in bytes. They will then initialize each of these elements to zero. Finally, a void pointer is returned to the memory.