50+ Embedded Developer Interview Questions and Answers

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

Memory stack stores local variables, while global and static variables are stored in the data segment.

• Local variables are stored on the stack, which is a region of memory that grows and shrinks as functions are called and return.

• Global variables are stored in the data segment, which is a fixed area of memory accessible throughout the program.

• Static variables, which retain their value between function calls, are also stored in the data segment.

• Example: In C, a local variable d...read more

Microprocessor is a standalone CPU while microcontroller has CPU, memory, and peripherals on a single chip.

• Microprocessor is used in applications where processing power is the main requirement, like computers.

• Microcontroller is used in embedded systems where space, power, and cost are constraints, like in IoT devices.

• Microprocessors require external components like memory and peripherals, while microcontrollers have them integrated.

• Examples of microprocessors include Intel Co...read more

Sorting a list of numbers in ascending order can be achieved using various algorithms or built-in functions.

• Use built-in functions like 'sort()' in Python: Example: numbers.sort()

• Implement sorting algorithms like Bubble Sort: Example: for i in range(len(arr)): for j in range(0, len(arr)-i-1): if arr[j] > arr[j+1]: arr[j], arr[j+1] = arr[j+1], arr[j]

• Consider using Quick Sort for efficiency: Example: def quick_sort(arr): if len(arr) <= 1: return arr; pivot = arr[len(arr) // 2];...read more

Microcontrollers are integrated circuits designed for specific tasks with built-in memory and peripherals, while microprocessors are general-purpose CPUs without built-in memory or peripherals.

• Microcontrollers are typically used in embedded systems for specific tasks, such as controlling a motor or sensor.

• Microcontrollers have built-in memory and peripherals, reducing the need for external components.

• Microprocessors are more versatile and used in general-purpose computing dev...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

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.

Interrupt latency is the time delay between the occurrence of an interrupt and the start of the routine that services the interrupt. A function pointer is a variable that stores the address of a function.

• Interrupt latency is critical in real-time systems where timely response to events is important.

• Interrupt latency can be reduced by optimizing the interrupt service routine.

• Function pointers are commonly used in C and C++ programming languages.

• Function pointers can be used to...read more

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

Yes, I have developed software from scratch for various projects.

• I have experience developing software from scratch for projects in the automotive industry.

• I have created custom firmware for embedded systems starting from a blank slate.

• I have built applications from the ground up using C/C++ and Python.

• I have designed and implemented algorithms for real-time processing in embedded systems.

Static keyword is used to declare variables and functions that are only accessible within the file they are declared in.

• Static variables retain their value between function calls

• Static functions can only be called within the file they are declared in

• Static variables in functions are initialized only once

Schematic diagrams are visual representations of a circuit's components and connections.

• Schematic diagrams use symbols to represent components like resistors, capacitors, and transistors.

• Lines connecting the symbols show how the components are connected in the circuit.

• Schematic diagrams help engineers and developers understand and troubleshoot circuits.

• Example: A schematic diagram of a simple LED circuit would show the LED symbol connected to a resistor and a power source.

ARM Cortex-M series controllers have a register level architecture for low-level programming and control.

• ARM Cortex-M series controllers have multiple registers for controlling various functions such as GPIO, timers, and interrupts.

• Registers are memory locations within the processor used for storing data and control information.

• Programmers can directly access and manipulate these registers to configure the behavior of the controller.

• For example, the GPIO registers can be used...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.

Developing Linux device drivers involves understanding the Linux kernel, writing code to interact with hardware, and testing the driver.

• Understand the Linux kernel architecture and device model

• Write the driver code to interact with the hardware

• Compile the driver code and load it into the kernel

• Test the driver to ensure proper functionality

• Handle errors and debug issues as needed

Microprocessors are general-purpose processors while microcontrollers are specialized processors for specific tasks.

• Microprocessors are used in computers and smartphones, while microcontrollers are used in embedded systems like washing machines and traffic lights.

• Microprocessors have separate memory and I/O devices, while microcontrollers have integrated memory, I/O ports, and peripherals.

• Microprocessors require external components for operation, while microcontrollers are se...read more

I2C is a synchronous serial communication protocol that uses a master-slave architecture, while SPI is a full-duplex communication protocol with a master-slave relationship.

• I2C uses two wires for communication (SDA and SCL), while SPI typically uses four wires (MISO, MOSI, SCK, and SS).

• I2C supports multiple devices on the same bus with unique addresses, while SPI requires a separate SS line for each device.

• I2C has a lower data transfer rate compared to SPI, but is more common...read more

Memory layout in C refers to how variables are stored in memory, including stack, heap, and data segments.

• Memory layout includes stack, heap, data segments

• Variables stored in stack have limited scope and size

• Dynamic memory allocation uses heap for storage

• Global and static variables stored in data segment

C program to convert binary to decimal

• Use a loop to iterate through the binary number from right to left

• For each digit, multiply it by 2 raised to the power of its position

• Add the result to a variable to calculate the decimal equivalent

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

I graduated with a degree in Computer Engineering from XYZ University, specializing in embedded systems and software development.

• Bachelor's degree in Computer Engineering from XYZ University.

• Completed coursework in embedded systems, microcontrollers, and real-time operating systems.

• Participated in a capstone project focused on developing a smart home automation system.

• Interned at ABC Tech, where I worked on firmware development for IoT devices.

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

Raspberry Pi is a small, affordable computer that can be used for various projects and applications.

• Single-board computer developed by the Raspberry Pi Foundation

• Runs on Linux-based operating system

• Used for educational purposes, DIY projects, IoT applications, etc.

• Example: Raspberry Pi 4 Model B