20+ TOP Embedded Systems Interview Questions and Answers
1. What is an embedded system?
An embedded system is a special purpose computer system which is completely encapsulated by device it control. It is a programmed hardware device in which the hardware chip is programmed with specific function. It is a combination of hardware and software.
2. What are the characteristics of embedded system?
The Characteristics of the embedded systems are as follows-
Real time behavior
Low manufacturing cost
Low power consumption
3. What are the types of embedded system?
They are of 4 types
Digital Signal Processing
Communication and network
4. What is digital signal controller ?
DSC is 16 bit RISC machine that combines control advantages of micro-controller and digital signal processing to produce tightly coupled single chip-single instruction stream solution for embedded system design.
5. What are the components of embedded system?
Microcontroller, microprocessor, DSC, DSP, busses, system clock, Read only Memory(ROM), RAM, Real time clock these are the components of embedded system.
6. Why we use embedded systems?
Embedded systems avoid lots of electronic components and they have rich built in functionality. They reduces the cost and maintenance cost and the probability of failure of embedded system is less so embedded system are in very much use now a days.
7. What are the languages used in embedded system?
Assembly language and C are basically used for embedded system. Java and ADA are also preferred.
8. How does combination of functions reduce memory reuirement in embedded system?
By using functions the amount of code that has to be dealt with is reduced thus redundancy is eliminated for everything common in function.
9. What is the significance of watchdog timer in ES?
It is a timing device which is set to predefined time interval and some task is to be performed at that time. It is used to reset original state when an inappropriate event take place.It is usually operated by counter device.
10. What is the difference between mutexes and semaphores?
Semaphores are the synchronization tool to overcome critical section problem.
Mutex is also a tool that is used to provide deadlock free mutual exclusion. It protects access to every critical data item, if the data is locked and is in use,it either waits for the thread to finish or awakened to release the lock from its inactive state.
11. What is the difference between FIFO and the memory?
FIFO (first in first out) is a memory structure where data’s can be stored and retrieved. This is a ueue where memory is a storage device which can hold data’s dynamically or at any desired locations and can be retrieved in any order.
12. What is an anti-aliasing filter?
Anti-aliasing filter reduces errors due to aliasing.
13. How to implement a fourth order Butter worth LP filter at 1 KHz if sampling freuency is 8 KHz?
A fourth order butter worth filter can be made as cascade of two second order LP filters with zeta of 0.924 and 0.383. One can use a bilinear transformation approach for realising second order LP filters. Using this techniue described well in many texts, one can make second order LP filters and cascade them
14. Is 8085 an embedded system?
It’s not an embedded system. B’coz it will be a part of an embedded system and it does not work on any software.
15.What is the role of segment register?
In the 8086 processor architecture, memory addresses are specified in two parts called the segment and the offset. Segment values are stored in the segment registers. There are four or more segment registers: Code Segment (CS) contains segment of the current instruction (IP is the offset), Stack segment (SS) contain stack of the segment (SP is the offset), DS is the segment used by default for most data operations; ES is an extra segment register.
16.What type of registers contains an INTEL CPU?
Special function registers like accumulator, program controller (PC), data pointer (DPTR), TMOD and TCON (timing registers), 3 register banks with r0 to r7, Bit addressable registers like B.
17. What is the difference between microprocessor and micro controller?
Microprocessor is managers of the resources (I/O, memory) which lie out-side of its architecture.
Micro controllers have I/O, memory etc. built into it and specifically designed for control.
18. DMA deals with which address (physical/virtual addresses)?
DMA deals with physical addresses. DMA controller is a device which directly drives the data and address bus during data transfer. So it is purely physical address.
19. What is the difference between testing and verification?
Verification is a front end process and testing is a post silicon process. Verification is to verify the functionality of the design during the design cycle. Testing is find manufacturing faults.
20. What is the reentrant function in embedded systems?
A reentrant function is used in embedded systems for executing multiple tasks together without any data corruption issues. This function can be paused at any time and restarted again based on the requirements. It protects local data and preserves global data by creating a local copy of that data. It must not call functions that are non-reentrant.