What Are The Reasons For Interrupt Latency And How Is It Reduced
Interviewers want to test your knowledge of the embedded processor architecture. It is necessary to know how to reduce interrupt latency to prevent slow response times in the system. You can define it and mention one or two causes in your response.
Example:”Interrupt latency is the time lapse between the generation of an interrupt to when the interrupt execution starts. One cause is the processor’s hardware. Every time an interrupt occurs, it is necessary to synchronise the signal with the cycles of the CPU clock. For the interrupt signal to reach the processor for processing, it may require at least three CPU cycles.
The instruction pipeline that modern CPUs use can also contribute to interrupting latency. The execution of instructions takes place at the last stage of the pipeline, and then it can take several CPU cycles to refill instructions in the pipeline. The time taken leads to interrupt latency. You can reduce interrupt latency by checking if your hardware disallows interrupt priorities and then shortening your interrupt routine. Since interrupt priorities are not allowed, a higher priority interrupt cannot disrupt an interrupt routine that has already started.”
Following Are Some Incomplete Declarations What Do Each Of Them Mean
1. const int x 2. int const x 3. const int *x 4. int * const x 5. int const * x const
- The first two declaration points 1 and 2 mean the same. It means that the variable x is a read-only constant integer.
- The third declaration represents that the variable a is a pointer to a constant integer. The integer value can’t be modified but the pointer can be modified to point to other locations.
- The fourth declaration means that the variable x is a constant pointer to an integer value. It means that the integer value can be changed, but the pointer can’t be made to point to anything else.
- The last declaration means that the variable x is a constant pointer to a constant integer which means that neither the pointer can point to a different location nor the integer value can be modified.
What Are Some Common Issues When Handling Interrupts
Interrupt handlers almost always need to finish their execution quicklythe details depend on the device and applicationand this limits the complexity of what can be done in their code. Also, the context in which the interrupt handler code is executed can, for either hardware or software reasons, prevent the usage from within the interrupt handler code of:
- Common library functions
- Access to peripherals and devices
- Even certain types of CPU instructions
The usual way to mitigate this is to have the interrupt controller set a special variable which is observed by non-interrupt code, and which can then perform arbitrary actions
What Are The Component Elements Of An Embedded System
Primarily, an embedded systems components are divided into three categories:
- Hardware Components: The various hardware components of an embedded system consisting of a power supply, CPU, memory, timer-counters, communication ports, input and output, and application-specific circuits such as a temperature sensor or alarm buzzer.
- Software Components: An embedded systems components include an assembler, an emulator, a debugger, and a compiler.
- Real-Time Operating System : This systems purpose is to supervise software components and provide a way for a processor to execute a process according to a schedule.
What Are The Essential Parts Of An Embedded System
Processors, memory, input/output devices, and software are the main components of an embedded system. The systems processor is responsible for executing the instructions that allow the system to function. Memory is where data and instructions are normally kept, and it is typically classified into two categories: ROM and RAM . Input/output devices, which include sensors, screens, and keyboards, are used to communicate with the outside world. The software instructs the machine on how to operate, and it is often stored in ROM.
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What Is The Volatile Keyword In Embedded C And What Is Its Usage
In Embedded C, the volatile keyword is a type qualifier that prevents the objects from compiler optimization. According to the C standard, we can modify the volatile-qualified type object in ways unknown to the implementation. In other words, we can say that the value of the volatile-qualified object can be changed at any time without making any changes in the code. If the volatile qualifier qualifies an object, the compiler will reload the value from memory each time the program accesses it. Reading the value from memory is the only way to check the unpredictable change of the value.
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.
What Is The Result Of The Below Code
void demo else }
In Embedded C, we need to know a fact that when expressions are having signed and unsigned operand types, then every operand will be promoted to an unsigned type. Herem the -40 will be promoted to unsigned type thereby making it a very large value when compared to 10. Hence, we will get the statement Greater than 10 printed on the console.
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Google Embedded Systems Engineer Interview Prep
Cracking the embedded system engineer interview at Google is not an easy task. You are pitted against some of the most talented contemporaries, and you need to prove to the hiring managers that you are better than your peers to get an inch closer to your dream job. Given that only a handful of candidates make it past the initial screenings, acing the Google Embedded Systems Engineer Interview Prep is more important than ever. At the Google ESE interview, prepare to be grilled on a variety of questions, including some curveballs!
If you are preparing for a tech interview at Google, check out our technical interview checklist, interview questions page, and salary negotiation ebook to get interview-ready! Also, read and for specific insights and guidance on tech interviews at Google.
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- Technical topics for Google Embedded Systems Software Engineer interview prep
Q25 What Are Hard And Soft Real
Ans:The hard real-time Embedded Systems are the ones that depend on the output very strictly on time. Any late response or delay cannot be tolerated and will always be considered a failure. The soft real-time systems on the other are not very rigid as the hard real-time systems. The performance of the system degrades with the lateness of response, but it is bearable and can be optimized to a certain level for reuse of the result.
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What Are The Main Advantages Of Embedded C
Embedded C is the extension of the C programming language. Let’s see the key advantages of Embedded C:
Key advantages of Embedded C:
- The coding speed of Embedded C is high, and it is simple and easy to understand.
- It doesn’t require any hardware changes such as extra memory or space for storage as it performs the same task all the time.
- It is dedicated to its specific task and performs only one task at one time.
- It is mainly used in modern automatic applications. Embedded applications are very suitable for industrial purposes.
Embedded System Design Interview Questions Jobs
I have a script that uses the discordjs library to forward messages between discord channels and it works perfectly but I need the embedded messages to be forwarded as normal text, that is, if in channel A I receive an embedded message, the bot extracts the content and send as content instead of embedded.Attached code to study the solution.
I’m looking for a reliable ghostwriter to create a steamy-contemporary, coming of age romance with some fantasy.This project is fo…speaking Able to write at least 15K words per week NO PLAGIARISM. No old ideas and nothing shared with a previous client. I want original content. Able to complete plot summaries and chapter-by-chapter plot outlines. I will provide the themes and tropes. Accessible and communicative. Professional work ethic. Revisions may be required and you would be compensated for them. A phone interview and signing a contract/NDA are required.Please send me the first three chapters from your best contemporary romance.Please start your proposal with the phrase I am a human.Thanks kindly for y…
I am looking for an expert laravel developer with knowledge in php, java, wordpress and api integration who will fix issues that i have to my platform. I only need senior developers and not amateurs. Developers from India or Pakistan are not in my priority.
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How Do You Improve Your Embedded Engineering Skills
Interviewers often ask this question to see if you understand the importance of upgrading your skills regularly. Given the rapid technological developments, embedded engineers can benefit professionally from keeping updated and expanding their knowledge. In your response, you can mention the steps you take to learn new skills.
Example:”Since my graduation, I have improved my skills through practical experiences. Aside from that, I have improved my understanding of hardware and electrical engineering concepts through undertaking online research and taking online classes. I also read articles and books on embedded engineering. I have set up search engine alerts on embedded engineering to stay informed on the latest happenings in this field.”
How Can You Reduce The Interrupt Latency
There are several ways to reduce the interrupt latency in Embedded C. The interrupt latency depends on many factors. Following is a list of some factors:
- Platform and interrupt controller
- Cache configuration
- Application program etc.
So, we can easily reduce the interrupt latency by using the proper selection of platform and processor. We can also reduce the interrupt latency by making the ISR shorter and avoid to calling a function within the ISR.
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What Do You Understand By Wild Pointer How Is It Different From Dangling Pointer
A pointer is said to be a wild pointer if it has not been initialized to NULL or a valid memory address. Consider the following declaration:
int *ptr *ptr = 20
Here the pointer ptr is not initialized and in the next step, we are trying to assign a valid value to it. If the ptr has a garbage location address, then that would corrupt the upcoming instructions too.
If we are trying to de-allocate this pointer and free it as well using the free function, and again if we are not assigning the pointer as NULL or any valid address, then again chances are that the pointer would still be pointing to the garbage location and accessing from that would lead to errors. These pointers are called dangling pointers.
Embedded System Design Interview Questions And Answers
Prepare for the types of questions you are likely to be asked when interviewing for a position where Embedded System Design will be used.
As technology advances, more and more businesses are looking for employees with experience in embedded system design. An embedded system is a computer system designed to perform a specific task, usually within a larger system. If youre interviewing for a position that involves embedded system design, you can expect the interviewer to ask questions about your experience and knowledge in the area. In this article, we review some of the most common questions you may be asked during your job interview.
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What Are Some Of The Ways We Use Timers In Embedded Systems
Timers in embedded systems can have numerous purposes, including the following:
- The systems Real Time Clock abbreviation is RTC.
- Kicking off an event following a delay of a certain amount of time.
- The beginning of an event follows a comparison of the previously specified times.
- Taking note of the count value displayed by the timer on an event.
- Determining the amount of time that has passed between two events.
- Time-slicing for a variety of different activities.
- Multiplexing using time division .
- RTOS task scheduling for all of the other jobs.
Could You Describe What A Watchdog Timer Is And How It Works
A watchdog timer is a timer that watches microcontroller programs to determine whether or not they are out of control or have ceased operation. It serves as a watchdog for MCU operations. A microcontroller is a small controller used to manage electronic devices. MCUs are pre-loaded with program software whose commands control electronic equipment and are integrated into a wide variety of electronic devices.
It makes it essential to ensure regular MCU operation. In the worst-case scenario, if the MCU software becomes unmanageable or stops functioning, the electronic equipment may behave unpredictably, resulting in damage or an accident.
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What Is The Segmentation Fault Error In C What Are Some Common Causes For The Segmentation Fault Error
Segmentation fault error is a runtime error, which may occur due to some causes when a program runs.
Following is a list of some common causes for the segmentation fault error in C:
- Usages of the dereferenced pointer: If we use a pointer that may not have a valid address/memory location to point, it may create a segmentation fault error.
- A program may return a segmentation fault error if you try to access a read-only memory area.
- Segmentation fault error may also occur when you try to free memory , which is already freed.
- The occurrence of segmentation fault error is the reason to generate stack overflow error in C.
How Does Testing For Embedded Software Differ From Testing For Other Forms Of Software Such As Web And Mobile Applications
Embedded software is frequently evaluated on the hardware it will run on rather than in a simulator or emulation. It is one of the primary differences. Because the software is meant to interact intimately with the hardware, any defects or faults must be discovered and resolved on the hardware. Another distinction is that embedded software is frequently tested for real-time performance and power consumption, which are crucial aspects of many embedded systems.
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In An Embedded System What Does Rtos Stand For
Real-Time Operating System is the complete version of the acronym RTOS. In an embedded system, the primary function of an RTOS is to provide support for real-time applications. These applications can handle data without being hindered by buffer delays. Additionally, it takes care of the complicated hardware aspects. An embedded system makes use of an RTOS because it is capable of meeting real-time deadlines and can effectively manage complexity.
Sample Questions For Google Embedded Systems Software Engineer Interview Prep
Hereâs a list of questions you can use for your embedded system engineer interview prep. Please remember that this is only an indicative list to give you a sense of what to expect:
- How to avoid memory fragmentation when targeting embedded devices?
- What are the different ways of reducing power consumption in an embedded system?
- Whatâs the difference between a process and a thread?
- What are common issues in handling interrupts?
- What is a semaphore? What are the different types?
- Can semaphores be used for interrupt context in Linux Kernel?
- How is the keyword “Volatile” used?
- What is the meaning of the keyword “const”?
- What is a watchdog timer?
- What are the important metrics of real-time software?
- What are the advantages and disadvantages of using a real-time operating system on a mid-range microcontroller?
- Why are C and C++ still popular and widely used in embedded systems?
- What are the benefits of using C/C++ vs. higher-level languages?
- How does one code an infinite loop in C?
- What is the difference between using an inline function and a macro?
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Why Does Interrupt Latency Happen
It happens because
- The signal synchronization with the CPU depends on the hardware of the processor. It can take up to 3 CPU cycles for a signal to reach the processor.
- After the execution of an instruction, it takes some extra CPU cycles to refill the pipeline again with the instructions. This leads to latency.
Can You List And Briefly Describe The Four Different Types Of Inheritance Relationships
What you want to hear: The candidate should explain what single, multiple, multi-level and hybrid inheritance relationships are and how they help establish a hierarchy in programming languages.
Red flag: An inability to understand basic organizational principles in programming may indicate a candidate is not well-informed on the best practices of their industry. Even if they cannot easily articulate each individual relationships meaning, they should be able to touch upon their importance.
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How Will You Swap Two Variables Write Different Approaches For The Same
- Using Extra Memory Space:
int num1=20, num2=30, temp temp = num1 num1 = num2 num2 = temp
- Using Arithmetic Operators:
int num1=20, num2=30 num1=num1 + num2 num2=num1 - num2 num1=num1 - num2
- Using Bit-Wise Operators:
int num1=20, num2=30 num1=num1 ^ num2 num2=num2 ^ num1 num1=num1 ^ num2
- Using One-liner Bit-wise Operators:
int num1=20, num2=30 num1^=num2^=num1^=num2
The order of evaluation here is right to left.
- Using One-liner Arithmetic Operators: