Changing report filter of Pivot table through macro

I need help writing a macro which is supposed to change the report filter (which contains dates up to the current date) of a Pivot table.
I want to be able to enter a date on a second sheet in cell A1 and the macro should basically change the report filter to the date I entered there. The macro button will be on the second sheet, too, so I won't have to go back to the Pivot table at all to change the filter.
I appreciate any suggestions and thoughts! Thanks!