Answers for the Embedded Engineer Interview Questions: Part-2

Preparing for an embedded engineering interview or examination can be challenging, given the technical depth and variety of topics covered.

However, understanding and practicing the right set of questions can make a significant difference. Below, we delve into how these questions and answers are instrumental in preparing for interviews and exams, ensuring aspirants are ready for the challenges ahead.

Importance of These Questions

1. Comprehensive Technical Understanding: The questions are carefully selected to cover essential concepts in embedded systems, including communication protocols, timers, interrupts, data transfer methods, and device initialization. These topics form the foundation of embedded engineering, making it crucial for aspirants to master them.
2. Real-World Application: Embedded engineering interviews often test practical knowledge. Questions like configuring a serial line driver or understanding CAN frame fields directly relate to tasks engineers perform in real-world projects.
3. Industry-Relevant Skills: Topics like DMA-based data transfer, I2C bus control bits, and Linux device drivers reflect the current industry standards and practices. Familiarity with these concepts helps candidates align their knowledge with industry expectations.

Interview Preparation Benefits

1. Clarity in Core Concepts: For instance, understanding the difference between synchronous and asynchronous communication provides clarity on when and why specific communication methods are preferred in embedded systems.
2. Problem-Solving Approach: Questions like “Explain how the vector addresses for an interrupt source can be used” encourage candidates to think critically about system architecture and troubleshooting.
3. Confidence Boost: Detailed yet concise answers equip aspirants with the confidence to tackle similar questions during interviews. Familiarity with terminology and processes ensures they can articulate their knowledge effectively.

Examination Preparation Benefits

1. Structured Learning: The systematic breakdown of questions ensures that aspirants cover each topic thoroughly. From basic definitions to practical applications, this approach builds a strong conceptual framework.
2. Retention of Knowledge: Revisiting questions like “What are the important uses of a Timer Device in an Embedded System?” helps reinforce memory, ensuring candidates can recall information quickly during exams.
3. Preparation for Objective and Descriptive Questions: The mix of theoretical and practical questions ensures aspirants are ready for both types of exam formats.

How to Use This Resource Effectively

1. Practice Regularly: Review the questions and answers periodically to solidify understanding. Repetition is key to retaining technical knowledge.
2. Simulate Interviews: Practice answering these questions aloud or in a mock interview setting to improve articulation and confidence.
3. Research Further: Use these questions as a starting point to dive deeper into related topics. For example, exploring additional use cases of virtual devices or researching advanced CAN bus protocols.

1. Explain the ten ways by which the synchronous signals with the clocking information transmit from a master device to a slave device.

Answer:

1. Clock signal transmission.
2. Embedded clock in data signal (e.g., Manchester encoding).
3. Separate clock line.
4. Data strobe synchronization.
5. Phase-locked loop (PLL) for clock recovery.
6. Master-slave clock gating.
7. Serial clock embedded in a differential pair.
8. Multi-drop clock distribution.
9. Clock and data recovery (CDR).
10. Synchronous parallel bus timing.

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2. Discuss two important characteristics of synchronous communication.

Answer:

1. Clock dependency ensures synchronization between sender and receiver.
2. Higher data transfer rate due to continuous data transmission.

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3. Discuss two important characteristics of asynchronous communication.

Answer:

1. No clock signal; data is transmitted with start and stop bits for synchronization.
2. Suitable for low-speed communication with variable data transmission intervals.

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4. What are the important uses of Timer Device in an Embedded System?

Answer:

1. Generating time delays.
2. Scheduling periodic tasks.
3. Event counting.
4. Capturing timestamps of external events.
5. Pulse Width Modulation (PWM) generation.

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5. How does the start and end of a byte or data frame is indicated in the CAN bus?

Answer:

• Start: Dominant bit (logic 0) marks the start of the frame.
• End: Seven recessive bits (logic 1) indicate the end of the frame.

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6. Compare the advantages and disadvantages of data transfer using serial and parallel ports/devices.

Answer:

• Serial Advantages: Simple wiring, long-distance communication, cost-effective.
• Serial Disadvantages: Slower data transfer.
• Parallel Advantages: High-speed data transfer.
• Parallel Disadvantages: Limited to short distances, complex wiring, expensive.

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7. Explain the use of each control bit of I2C bus.

Answer:

1. Start Condition (S): Initiates communication.
2. Stop Condition (P): Terminates communication.
3. Acknowledge (ACK): Confirms successful data reception.
4. Repeated Start (Sr): Allows communication without releasing the bus.
5. Read/Write (R/W): Indicates data direction.

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8. What are the advantages of DMA based data transfer over the interrupt driven data transfer?

Answer:

1. Reduces CPU overhead.
2. Enables high-speed data transfer.
3. Allows concurrent CPU processing.

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9. What are the uses of hardware assigned priorities in an interrupt mechanism?

Answer:

1. Resolves multiple interrupt requests.
2. Ensures critical tasks are serviced first.

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10. Explain how do you use the vector address for an interrupt source?

Answer:

• Vector address directs the processor to the specific interrupt service routine (ISR) associated with the interrupt source.

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11. List some of the useful Linux Device Drivers for the Embedded System.

Answer:

1. Character device driver.
2. Block device driver.
3. Network device driver.
4. USB driver.
5. GPIO driver.

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12. What are Virtual Devices?

Answer: Virtual devices are software emulations of physical devices, allowing the operating system to interact with non-existent hardware resources.

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13. Give some examples of virtual devices.

Answer:

1. Virtual Network Interfaces.
2. Virtual Hard Drives (e.g., VHD, VMDK).
3. Virtual Printers.

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14. What are the advantages of busy and wait transfer mode for I/O devices?

Answer:

1. Simple implementation.
2. Ensures data is processed as soon as it is available.

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15. What are the disadvantages of busy and wait transfer mode for I/O devices?

Answer:

1. CPU remains idle while waiting.
2. Inefficient for multitasking systems.

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16. Explain the details of each field in a CAN frame.

Answer:

1. Start of Frame (SOF): Indicates the beginning.
2. Identifier: Priority and address of the frame.
3. Control Field: Data length information.
4. Data Field: Payload data.
5. CRC Field: Error checking.
6. ACK Field: Acknowledgment of receipt.
7. End of Frame (EOF): Marks the end.

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17. Taking the example of the serial line driver at the COM port of a PC, explain how a device is initialized and configured?

Answer:

1. Initialize communication parameters (baud rate, parity, stop bits).
2. Configure buffer sizes.
3. Set control signals (RTS, CTS).
4. Enable interrupts or polling for data transfer.

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18. Explain how the vector addresses for an interrupt source be used?

Answer:

• Vector addresses map each interrupt source to a unique memory location, ensuring the CPU can quickly locate and execute the corresponding ISR.