First interview was supposed to be over the phone, but since I was nearby I was invited on site. The hiring manager asked me a bit about myself, stuff that I did (from my resume) etc. Then on to the coding challenge. The coding challenge was very simple, a Raspberry Pi with interfacing to a LED driver was set up, I was to program directly on it. The questions were about utilizing existing C/C++ API to send commands to the driver and control the LED. Later a full day of interviews with the various management levels followed, and I was also asked to make a presentation before the team. But there was only one "Professional" interview