20+ Embedded Developer Interview Questions and Answers for Freshers

A null pointer points to nothing while a void pointer can point to any data type.

• A null pointer is a pointer that has been explicitly set to a null value.

• A void pointer is a pointer that has no type associated with it.

• A null pointer is a subtype of a void pointer.

• A null pointer is used to indicate that a pointer does not point to a valid object.

• A void pointer is used to store a pointer to any type of object.

Storage class specifiers in C are used to define the scope and lifetime of variables.

• There are four storage class specifiers in C: auto, register, static, and extern.

• Auto variables are local to a block and have automatic storage duration.

• Register variables are stored in CPU registers for faster access.

• Static variables have a lifetime throughout the program and are initialized only once.

• Extern variables are declared in one file and can be used in other files.

• Storage class spec...read more

Flip-flops are fundamental digital memory circuits used to store binary data, functioning as bistable devices.

• Bistable Device: Flip-flops can hold one of two states (0 or 1), making them essential for storing binary information.

• Types of Flip-Flops: Common types include SR (Set-Reset), D (Data), JK, and T (Toggle) flip-flops, each serving different purposes.

• Clock Signal: Flip-flops are triggered by clock signals, which synchronize their state changes, ensuring reliable data st...read more

Preprocessor in C is a tool that processes source code before compilation.

• It performs macro substitution

• It includes header files

• It conditionally compiles code

• It defines constants and symbols

• It removes comments

• Examples of preprocessor directives are #include, #define, #ifdef, #ifndef, #endif

• Preprocessor directives start with a # symbol

Kernel space is a protected area of memory where the core of the operating system resides. Device drivers are software that allows the operating system to communicate with hardware devices.

• Kernel space is a privileged area of memory that is reserved for the core components of the operating system.

• Device drivers are software modules that facilitate communication between the operating system and hardware devices.

• Experience in device drivers may involve writing, debugging, or op...read more

Microcontrollers integrate a CPU, memory, and peripherals on a single chip, while microprocessors focus on processing power.

• Integration: Microcontrollers combine CPU, RAM, ROM, and I/O peripherals on one chip, e.g., Arduino (ATmega328).

• Processing Power: Microprocessors, like Intel Core i7, are designed for high-performance tasks and require external components.

• Power Consumption: Microcontrollers are optimized for low power consumption, making them ideal for battery-operated d...read more

Function pointer is a variable that stores the address of a function and can be used to call that function.

• Function pointers are used to pass a function as an argument to another function.

• They can be used to implement callbacks and event handlers.

• Function pointers can be used to implement polymorphism in C.

• They can be used to switch between different implementations of a function at runtime.

This code configures and reads ADC values on STM32 microcontrollers, enabling analog signal processing in embedded applications.

• Initialization: Configure the ADC peripheral using HAL functions, e.g., HAL_ADC_Init().

• Channel Selection: Select the ADC channel to read from, e.g., ADC_CHANNEL_0.

• Start Conversion: Use HAL_ADC_Start() to begin the conversion process.

• Polling for Conversion: Wait for the conversion to complete using HAL_ADC_PollForConversion().

• Read Value: Retrieve the ...read more

Interrupts are signals sent to the processor to temporarily halt its current task and execute a specific task.

• Hardware interrupts - generated by external devices

• Software interrupts - generated by software programs

• Maskable interrupts - can be disabled by the processor

• Non-maskable interrupts - cannot be disabled by the processor

• Examples - keyboard input, mouse input, timer interrupts, etc.

SPI, UART, and I2C are communication serial protocols used in embedded systems to transfer data between devices.

• SPI (Serial Peripheral Interface) is a full-duplex synchronous communication protocol commonly used for communication between microcontrollers and peripheral devices.

• UART (Universal Asynchronous Receiver/Transmitter) is a serial communication protocol that uses two wires for data transmission and is commonly used for communication between devices over longer distanc...read more

Program to implement matrix multiplication in C++.

• Declare two matrices A and B of appropriate dimensions.

• Initialize the matrices with values.

• Create a result matrix C with dimensions rows of A and columns of B.

• Perform matrix multiplication using nested loops.

• Print the result matrix C.

An ultrasonic sensor is a device that uses sound waves to measure distance and detect objects.

• Uses high frequency sound waves to bounce off objects and measure distance

• Commonly used in robotics and automation for object detection and avoidance

• Can also be used in parking sensors, security systems, and medical imaging

• Works by emitting a sound wave and measuring the time it takes for the wave to bounce back

OS boot up sequence involves several steps such as BIOS initialization, bootloader loading, kernel loading, and initialization of system services.

• BIOS (Basic Input/Output System) initialization

• Bootloader loading (e.g. GRUB, LILO)

• Kernel loading and initialization

• Init process execution

• System services initialization

Electric fields arise from charged particles, while magnetic fields are produced by moving charges or magnetic materials.

• Source: Electric fields are generated by stationary electric charges, while magnetic fields are created by moving charges (currents).

• Direction: Electric fields point away from positive charges and toward negative charges, whereas magnetic fields have a direction defined by the right-hand rule.

• Units: Electric fields are measured in volts per meter (V/m), whi...read more

To reverse a string, iterate through the characters from the end to the beginning and build a new string.

• Create a new string to store the reversed result.

• Iterate through the original string from the end to the beginning.

• Append each character to the new string.

• Return the reversed string.

I am expecting a competitive salary based on my skills and experience.

• I am open to negotiation based on the job requirements and responsibilities.

• I am looking for a salary that is in line with industry standards.

• I am willing to discuss benefits and other compensation packages.

• I am not comfortable sharing my current salary as it is confidential.

• I am looking for a long-term career opportunity with growth potential.

A simple LED blink program toggles an LED on and off at regular intervals using a microcontroller.

• Initialize the GPIO pin connected to the LED.

• Set the pin mode to OUTPUT.

• Use a loop to toggle the LED state.

• Implement a delay function to control the blink rate.

• Example: Use a delay of 500ms for a 1Hz blink rate.

Sensors are devices that detect and respond to physical stimuli.

• Temperature sensors (thermocouples, RTDs, thermistors)

• Pressure sensors (piezoresistive, capacitive, piezoelectric)

• Motion sensors (accelerometers, gyroscopes, magnetometers)

• Light sensors (photodiodes, phototransistors, photovoltaic cells)

• Gas sensors (carbon monoxide, oxygen, carbon dioxide)

• Humidity sensors (capacitive, resistive)

• Proximity sensors (inductive, capacitive, ultrasonic)

The question is asking for code in the C language.

• Use the 'C' programming language syntax to write the code.

• Include necessary libraries and headers.

• Provide a clear and concise solution to the problem.

• Test the code thoroughly before submission.