Passing params when user hits nav bar back button

If I want to pass some data collected on the current view to the view the user is going back to via the nav-bar back button, how would I accomplish this?

Ps: I know about having the params defined ahead of time for the parent view, but not sure how to tie in the nav-bar action to set the toParams. Normally I would use the $state.go method but not sure about the case where the user is hitting the nav-bar back button.