I was contacted by email for a first round interview. Interview was broken into two 30 mins sessions with two separate interviewers. Then I was invited for another round which lasted for 4 hours.

First met with Hiring Manager. Was asked to describe the two blocks I had designed. Was asked probing questions about why and how I had made certain design decisions. Was asked how I interacted with people and give examples of a difficult situation I had handled. Then two Lead Engineers came in and asked me to give a presentation of a Specification document I had written. After that, I was shown two examples of code written by their Engineers and asked to explain what the code was doing.