First round typical phone screening. Second round got a controls challenge, it's a time delay system and was asked to design a controller for it. I got a email the very next day after I sent back the solution. They are very efficient and I was thoroughly impressed. Third round was about my resume projects, very detailed questions, down to almost the stability proof of my controller. Every detail was talked. I thought it went very well. But they told me the next week that it's not a good fit.