To get into bits Dubai I, you need to have good percentage in 12th exams. Then minimum marks needed is 60% overall and if you are having around 80% or above then it becomes very easy to get in. Every year, I guess the seats in bits Dubai  are increased for all branches and hence the cutoffs are decreased so now it becomes much more easier to get in.

The most demanding branches are electronic and then computer science.

So all the very best and give it a try.

Hey !
In order to get into Bits-Dubai, all you need to have is good percentage of marks in your 12 standard exams. As you stated that your percentage is 77, you can easily get into BITS- Dubai.The minimum marks needed is just 60 % overall aggregate. And if you are getting like 75-80% or above then surely you are in. In BITS Dubai mostly students take up Electronics branch and the second most suggested is Computer Science. Choose according to your interest.
Hope this helps
All the best !