Firstly hardware test for ECE,EIC and software test for CSE.Then after shortlisting Max 2 rounds of Interviews. In Test,questions on CMOS,Mosfet,Digital,Setup time,hold time,Circuits of resistor,inductor,capacitor and aptitude(Very important consideration). 20 from ECE got selected.I was one of them. Then Interview Process-Why ST,What you will do there,Why should we choose you,What ST do,questions in Digital Electronics Mux,Hold Time,Aptitude.My Interview was stress level Inerview.Be calm and most important thing "Stay with your answer,they will try to grill you, don't get nervous"