A recruiter reached out to me on LinkedIn and set up a phone interview with the hiring manager. The phone interview was easy, mostly covering my background and previous projects. The main open-ended question was: if you received a uC board and it was not working, walk through all the steps to debug, both hardware and software, and how you would debug UART.

They then invited me for a 4-hour onsite interview with five people, including one person from HR.

The interviews were intense and all technical. All interviewers were polite and professional. Since I signed a paper, I cannot provide exact questions.

First interview: Lots of C programming questions, mostly pointers and structs.

Second interview: I was given the datasheet of an I2C device and questioned on how the device works and how to use it, including writing an API.

Third interview: Lots and lots of C programming, covering strings and memory management. You should be proficient in C to answer all the questions, and some basic networking questions, like router vs. switch and VLAN.

Fourth interview (with the manager): Create a specific malloc function.

Fifth interview: Doubly linked list operations (insertion, deletion, search), implemented in C. The interviewer did not know what a double pointer was or where to use it. Some questions were about Linux, the kernel, mutexes, and semaphores.

Finally, I met with an HR person.

The reason I am giving a negative rating to this interview experience is that they never contacted me after the onsite interview.

Mutex and Semaphores