Preparing for an Embedded Engineer interview at Roku requires a structured approach that balances low-level systems programming with robust software design. You cannot rely solely on algorithmic puzzle-solving; you must demonstrate a deep physical intuition for how software interacts with silicon.

Technical Breadth & Depth – You must show comfort across the entire embedded stack. Expect to be evaluated on everything from low-level assembly concepts and register-level programming to high-level object-oriented programming in C++. You should be ready to talk about memory-mapped I/O, interrupts, and DMA, as well as C++ templates, smart pointers, and design patterns.

Resource-Constrained Problem Solving – When writing code or designing systems, always think about memory efficiency and CPU cycles. Roku interviewers highly value candidates who proactively discuss complexity in terms of both time and space, especially when working within limited RAM footprints.

Concurrency & Thread Safety – Multi-threading is a major focus area at Roku. You should thoroughly review synchronization primitives, memory barriers, volatile variables, and thread-safety patterns. Be ready to write code that avoids race conditions and deadlocks, and be prepared to explain the underlying mechanics of your synchronization choices.

System Architecture & Design – You must be able to design modular, maintainable, and testable embedded software. This involves defining clean APIs, separating hardware-dependent code from business logic, and designing systems that can fail gracefully without crashing the entire device.

The interview process for an Embedded Engineer at Roku is thorough and typically spans several weeks. It is designed to test your technical capabilities, your problem-solving under pressure, and your alignment with Roku's engineering culture.

The process begins with an initial recruiter screen, followed by a technical screen with a hiring manager or tech lead that often includes a live coding component on a platform like Hackerrank. If you pass this screen, you will move to the virtual or onsite loop, which consists of multiple technical and behavioral interviews. These rounds dive deep into C++ coding, embedded system design, and behavioral scenarios.

The timeline above outlines the standard progression from your initial contact to the final decision. Candidates should use this timeline to pace their preparation, ensuring they allocate ample time to practice live coding before the technical screen and system design concepts before the onsite loop. While the process is rigorous, it is highly structured and provides clear milestones at each stage.

To succeed at Roku, you must perform consistently across several core competencies. Interviewers will evaluate you on specific technical domains that are critical to the day-to-day work of an embedded engineer.

C++ & Data Structures

At Roku, C++ is heavily utilized for application-level programming and system services. You are expected to write clean, efficient, and idiomatic C++ code. Interviewers will look at how you manage memory, handle pointers, and utilize standard library containers.

Be ready to go over:

• Pointer Manipulation – Deep understanding of raw pointers, reference semantics, and smart pointers (std::unique_ptr, std::shared_ptr).
• Memory Management – Stack vs. heap allocation, preventing memory leaks, and understanding custom allocators.
• Standard Template Library (STL) – Knowing when to use specific containers (e.g., std::vector vs. std::list) and their underlying performance characteristics.
• Advanced concepts (less common) – Move semantics, RAII (Resource Acquisition Is Initialization), and C++ templates for compile-time optimizations.

Example questions or scenarios:

• "Implement an efficient circular buffer (FIFO) in C++ without using STL containers, ensuring proper memory cleanup."
• "Write a function to detect and remove a loop in a singly-linked list."

Firmware & Low-Level Concepts

This area tests your ability to interact directly with hardware and write software that operates close to the metal. You need to demonstrate that you understand how a microcontroller or microprocessor executes code and interacts with peripherals.

Be ready to go over:

• Bitwise Manipulation – Masking, shifting, setting, clearing, and toggling specific bits in registers.
• Hardware Peripherals – Understanding common communication protocols like I2C, SPI, UART, and how drivers interact with them.
• Interrupts & DMA – Writing Interrupt Service Routines (ISRs), managing interrupt latency, and utilizing Direct Memory Access for zero-copy data transfers.
• Advanced concepts (less common) – Assembly language fundamentals, bootloader sequences, and flash memory wear leveling.

Example questions or scenarios:

• "Given a binary file containing packed 12-bit sensor readings, write a highly optimized C function to unpack and stream these values into a 16-bit array."
• "Explain how you would write a non-blocking driver for an SPI-based display."

Embedded System Design

System design at Roku focuses on how you architect complex software systems running on constrained devices. You will be asked to design components of a media streaming device, smart home hub, or system service.

Be ready to go over:

• Hardware-Software Boundary – Defining clear abstraction layers between hardware drivers, middleware, and applications.
• Multi-threaded Architecture – Structuring an application with multiple threads, defining communication channels (queues, IPC), and managing thread priorities.
• Resource Management – Designing strategies for low-power modes, thermal throttling, and memory constraint handling.
• Advanced concepts (less common) – Designing a secure boot pipeline or architecting an over-the-air (OTA) firmware update system.

Example questions or scenarios:

• "Design the software architecture for a remote control input processing service that must handle button presses, voice streaming, and low-power standby states."
• "Architect a logging framework for an embedded device that balances real-time performance, flash wear, and persistence across crashes."

As an Embedded Engineer at Roku, your day-to-day responsibilities will vary depending on your specific team, but they will generally center around the development, optimization, and maintenance of Roku OS and its supporting hardware platforms.

You will spend a significant portion of your time writing high-performance C and C++ code. This includes developing device drivers, implementing system services, and optimizing middle-tier software components. You will work closely with hardware partners and silicon vendors to bring up new system-on-chip (SoC) platforms, debug hardware-software integration issues, and ensure that new hardware designs meet Roku's strict performance and reliability standards.

Collaboration is a key aspect of the role. You will partner with product managers to understand feature requirements, work alongside QA engineers to design automated testing frameworks for embedded systems, and collaborate with cloud services teams to build secure, efficient APIs for device-to-cloud communication. You will also be responsible for profiling system performance, identifying bottlenecks in CPU and memory utilization, and continuously refactoring legacy code to improve system stability and maintainability.