Embedded Systems Interview Questions and Answers

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:

The difference between microprocessor and microcontroller are:

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:

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.

The mutex is known as Mutual Exclusion. This is usually used by tasks for giving exclusive access to a shared resource. It can be used for multiple tasks or threads in a system.

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.

• 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.