Ques 1. What is embedded C?

Embedded C is a set of extensions to the C programming language specifically designed for embedded systems.

Ques 2. What is a volatile variable in C?

The volatile keyword tells the compiler that a variable's value may change at any time, without any action being taken by the code.

Example:

volatile int sensorValue;

Ques 3. Explain the significance of the 'const' keyword in embedded C.

'const' is used to define constants in C, and in embedded systems, it helps in better code optimization and memory management.

Example:

const int MAX_SIZE = 100;

Ques 4. What is the purpose of the 'volatile' keyword in C?

The 'volatile' keyword is used to indicate that a variable may be changed by external factors, such as an interrupt service routine.

Example:

volatile int flag;

Ques 5. Explain the concept of polling in embedded systems.

Polling involves regularly checking the status of a device or condition within the code, often used for input or communication handling.

Ques 6. What is the role of the 'static' keyword in embedded C?

In embedded C, 'static' can be used to define variables with a fixed memory location or limit the scope of functions and variables.

Example:

static int counter = 0;

Ques 7. What is the purpose of a preprocessor in C?

The preprocessor performs tasks such as macro substitution, file inclusion, and conditional compilation before the actual compilation of the code.

Example:

#define PI 3.14

Ques 8. What is the purpose of the 'inline' keyword in C?

The 'inline' keyword suggests to the compiler that a function should be expanded in-place at the call site, potentially improving performance.

Example:

inline int add(int a, int b) { return a + b; }

Ques 9. What is the purpose of the 'const' pointer in C?

A 'const' pointer points to a constant value, meaning the value it points to cannot be modified through the pointer.

Example:

const int *ptr;

Ques 10. What is the purpose of the 'enum' keyword in C?

The 'enum' keyword is used to define named integer constants, providing a more readable alternative to using raw integer values.

Example:

enum Days { Monday, Tuesday, Wednesday, Thursday, Friday };

Ques 11. Explain the difference between a microcontroller and a microprocessor.

A microcontroller integrates a processor with peripheral devices like timers, communication ports, and memory on a single chip. A microprocessor, on the other hand, only includes the CPU.

Ques 12. What is the purpose of a watchdog timer in embedded systems?

A watchdog timer is used to reset the microcontroller if the software hangs or encounters an error, ensuring system reliability.

Ques 13. How does dynamic memory allocation differ in embedded systems compared to desktop applications?

Embedded systems often avoid dynamic memory allocation due to limited resources and potential fragmentation issues.

Ques 14. Explain the role of a linker script in embedded C programming.

A linker script defines the memory layout of an embedded system, specifying the placement of code and data in the target memory.

Ques 15. What is bit masking, and how is it used in embedded C?

Bit masking involves setting or clearing specific bits in a variable to enable or disable certain features, often used in register manipulation.

Example:

#define ENABLE_BIT  (1 << 3)  // Enable bit 3

Ques 16. Explain the concept of a real-time operating system (RTOS) in embedded systems.

An RTOS is designed for time-sensitive applications, ensuring timely execution of tasks and handling events in real-time.

Ques 17. How is interrupt handling implemented in embedded C?

Interrupt handling involves defining ISR (Interrupt Service Routine) functions to respond to specific events or external signals.

Example:

void ISR_Timer() { /* code for timer interrupt */ }

Ques 18. Explain the significance of the 'register' keyword in embedded C.

The 'register' keyword suggests to the compiler that a variable should be stored in a CPU register for faster access.

Example:

register int count;

Ques 19. What is a semaphore in embedded systems?

A semaphore is a synchronization mechanism used to control access to shared resources, preventing race conditions in multitasking environments.

Ques 20. How does a UART communication work in embedded systems?

UART (Universal Asynchronous Receiver/Transmitter) is a popular serial communication protocol in embedded systems, transmitting data bit by bit asynchronously.

Ques 21. Explain the concept of bit fields in C.

Bit fields allow the definition of variables that occupy a specific number of bits in a structure, aiding in efficient memory usage.

Example:

struct Flags { unsigned int flag1:1; unsigned int flag2:1; };

Ques 22. What is the purpose of the 'restrict' keyword in C?

The 'restrict' keyword informs the compiler that a pointer is the only means to access a particular area of memory, helping in optimization.

Example:

void foo(int *restrict ptr);

Ques 23. Explain the concept of reentrant functions in embedded systems.

Reentrant functions can be safely interrupted and resumed, making them suitable for use in multitasking environments where multiple tasks may call the same function simultaneously.

Ques 24. Explain the role of a bootloader in embedded systems.

A bootloader is a program that loads the main application into the microcontroller's memory, typically from external storage like flash or EEPROM.

Ques 25. Explain the concept of polling versus interrupt-driven I/O.

Polling involves repeatedly checking the status of a device, while interrupt-driven I/O relies on hardware interrupts to notify the processor when the device needs attention.

Ques 26. Explain the role of a timer in embedded systems.

Timers are used to measure time intervals, generate time delays, or trigger events at specific intervals, crucial for tasks like real-time control.

Ques 27. What is the purpose of the 'volatile' qualifier in function arguments?

The 'volatile' qualifier in function arguments indicates that the argument may change unexpectedly, even if it appears not to be modified within the function.

Example:

void process_data(volatile int data);

Ques 28. Explain the concept of DMA (Direct Memory Access) in embedded systems.

DMA allows peripherals to directly access the system's memory without involving the CPU, improving data transfer speed and reducing CPU overhead.

Ques 29. What is the purpose of the 'attribute' keyword in GCC (GNU Compiler Collection)?

The 'attribute' keyword is used to specify additional information to the compiler, such as optimizing for size or alignment.

Example:

attribute((packed)) struct PackedStruct { / members */ };

Ques 30. Explain the concept of stack and heap in embedded systems.

The stack is used for local variables and function call management, while the heap is used for dynamic memory allocation, managed by the programmer.