Hello Prem,

You'll have to appear for the AP ECET test which is an offline test three papers of Maths, Physics and Chemistry and a paper on Engineering (in your case ECE)
OBCs have a 29% seat reservation in colleges
OBC candidates need not submit any certificates while appearing for the examination. However, ALL students have to produce the Category Certificates at the time of admission.
You must have a rank within 2000 to get admission

Hope this helps!
Good luck!