Hey.. 340 rank in ECET is good of course you will get admission in good university in AP. CSE is good branch and of course the demanded one. Keep trying you will get the best 

Hi jagadeesh!!
Wow man you have scored a very good rank in your APECET. 340 Is a very good rank and there is a chance for you to get admission in one of the universities in AP. Also if you are a BC or SC caste then it will be easy to yo but the branch CSE is becoming very popular in AP. Of course don't worry man first of all you try to keep counselling and there may be a chance in which a big university can offer you a chance but with different branch like mechanical engineering etc.
ALL THE VERY BEST!!