It was primarily based on our mini project. Mine was a microprocessor based one , so they kept on asking more about microprocessors and microcontrollers and their real life use with examples. Then they cover questions from every core subjects like analog , digital , industrial instrument etc. I was asked to draw the output waveform of certain circuits from analog electronics. The interview ended up with one simple programming question on C.
Note : They only check your knowledge on C programming and don't consider other language like python.
HR interview :
It was on the same day as of the technical interview. Only selected candidates from technical interview get a chance for HR interview.
It is just a casual talk and I don't think any selection process is done based on it.
Just the interviewer ask you about your family background and some silly personal question and its done. It only last for 4- 5 min