Two phone interviews for the same job position. First interview-asked me questions on my project listed on my resume. Basic questions in C like difference between & and &&, memory regions like stack, heap, text, data segments. OS concepts-what is mutual exclusion? Difference between semaphores and mutexes? Asked me to code (in C)a function which takes the bit number of an output port as argument and toggles it. Second interview-Did not discuss my resume at all. Dived straight into tech questions-What are interrupts and if you have less external interrupt pins on a processor, how to interface multiple interrupts? How do breakpoints in a C program work? How does a debugger work? Asked me to write a program(in C) to remove duplicate continuous characters in a string. Another way to find the sizeof and data type without using sizeof()? The second interview was a bit difficult and didn't think I would make it. Sure enough I get an email from their HR saying they want to hire someone who closely matches the job description so I was not invited to the on-site interview.

they call you and ask you the your availability and typical interview goes for 3 hours if they are interested. They ask C questions and your project related questions. At last a manager comes and takes your interview.