Can I make a bidirectional BLE device from nRF51822?

[Franz]

I need a BLE device that can broadcast codes/id to my android mobile app. Also, I need those codes be changed by once in a while by an admin app. Is this possible?

[shibshab]

Yes, you would need to expose the field as a writable attribute in the broadcasters GATT database, and then make sure that the advertised data is updated with whatever is written to those attributes.