Asked about basic C/programming questions, what does static mean, interrupts. More broad questions, what do you know about the company, etc. Encouraged questions about the company and what they do.

Had a one-hour phone interview and was offered an internship the next morning. The three interviewers on the phone were all software engineers, and asked programming questions and logic puzzles. The logic puzzles were interesting to think through. When I was unfamiliar with terminology or specific coding details, they had no problem with that and guided me toward the answer based on concepts I did know. It was more for them to see how I think, rather than what I know (unlike some other software interviews I've done). Overall, it was a fun interview and the interviewers seemed very enthusiastic. HR was very helpful and personable.