How to use flutter_blue_elves to show widgets as needed?

I need to connect to a ble sensor and show the data in a phone app, I tried the flutter_blue_elves example, it works well.

But it don't work after I did some changes in device_control.dart to show some different widgets,  why? I only changed the build part.

So, how to use flutter_blue_elves to show widgets as needed?

Or, is it possible to use flutter_blue_elves as a backgrougnd service?


