Silicon Labs India SDET Interview: Rounds, Questions and Preparation

What the job involves

As an SDET at a global semiconductor or embedded products company, you design, build, and maintain automated test frameworks and test suites that validate firmware, drivers, and software tools. Day to day you write code to test code, investigate failures, and work with developers to improve product quality. Freshers usually start with test automation for embedded software or hardware-software interaction.

Role and technical knowledge

1. 1

   What is the difference between a manual test and an automated test, and when would you choose each for embedded software?

   A strong answer explains that automated tests are best for repetitive, regression, and hardware-in-loop checks, while manual tests suit exploratory or one-time hardware setup checks. Mention cost, stability, and maintenance.

2. 2

   Explain how you would test a firmware update process on a microcontroller.

   Cover valid and invalid firmware files, interrupted updates, power loss recovery, version rollback, and verification that the device boots correctly. Mention logging and recovery modes.

3. 3

   What is a test harness, and how does it differ from a test framework?

   A test harness is the set of tools and scripts that run tests and report results, often including stubs and drivers. A framework is a reusable structure or library for writing and organising tests. Give a small example.

4. 4

   How would you test a simple sensor driver that reads temperature over I2C?

   Include boundary values, error conditions like NACK or timeout, register read/write checks, and comparison against a reference sensor. Mention mocking the I2C bus for unit tests.

Practical scenarios and coding

1. 5

   Write a function in Python or C that checks if a given string is a palindrome, ignoring case and non-alphanumeric characters.

   Show clean code, edge case handling for empty strings and single characters, and mention time complexity. Explain your test cases for this function.

2. 6

   You have a test that fails only on one specific hardware board but passes on others. How do you debug it?

   Start by reproducing reliably, compare board revisions and firmware versions, check power and clock settings, and isolate with minimal test code. Mention logging and using a debugger or oscilloscope.

3. 7

   How would you automate a test that requires a device to be power cycled 100 times and report failures?

   Describe using a programmable power supply or relay controlled by a script, a loop with error handling, and logging each cycle result. Mention safety and recovery if the device hangs.

4. 8

   Given a log file with thousands of lines, how would you write a script to find all unique error codes and their counts?

   Explain reading the file line by line, using a dictionary or hash map to count, and filtering by a pattern. Mention using regular expressions and sorting the output.

Behavioural and teamwork

1. 9

   Tell me about a time you found a bug in a project. How did you report it and what happened next?

   Use a clear structure: what you were doing, how you found the bug, how you documented it with steps to reproduce, and how the team fixed it. Show ownership and communication.

2. 10

   Describe a situation where you had to learn a new tool or technology quickly for a college project.

   Focus on your learning method, resources used, and the outcome. Mention how you applied it and what you would do differently.

3. 11

   How do you handle disagreement with a teammate about whether a bug is valid?

   Show that you listen, gather evidence like logs or test results, and escalate politely if needed. Emphasise the goal of product quality over being right.

4. 12

   Why do you want to work as an SDET rather than a pure developer role?

   Connect your interest in breaking software, building tools, and ensuring quality. Mention that you enjoy coding but also like the detective work of finding root causes.

HR and company fit

1. 13

   What do you know about our company and why does this role interest you?

   Research the company's products like microcontrollers, wireless chips, or development tools. Link your skills to testing embedded software and mention a specific product line or technology.

2. 14

   Are you willing to relocate or work in different time zones for global projects?

   Be honest and positive. Mention flexibility, willingness to learn about global collaboration, and any constraints clearly.

3. 15

   Where do you see yourself in three years as an SDET?

   Show a growth path from writing tests to designing frameworks or leading automation for a product area. Mention skills you want to build like embedded debugging or CI/CD.

4. 16

   What are your salary expectations for this fresher role?

   Research typical fresher SDET salaries in India for product companies. Give a reasonable range and say you are open to the standard company package for the role.