How to assign a seperate controller to ionic modal?

Hi, I am trying to build a sign up modal in my app. I created two different controllers, one homeController and signupController. All the logic related to signup is included in signupController.

I specified signupController by adding ‘data-ng-controller’ attribute inside html of modal. Now I am opening signup modal from home controller.

The problem I am facing is that ther variables I am creating and using in signup modal are not being updated whenever I am updating html elements.

Could you provide any valueable suggestion??