The I/O View is confined to a single tool window in the development environment. There can only be one instance of the I/O view at a time. To open the window, select Debug -> Windows -> I/O View. When in design mode, the I/O View will be disabled for inputs. It is still possible to change the layout or filters, and to navigate the view, but no values can be set or read. To read or change a value in the registers, AVR Studio must be in debug break mode (execution paused). In this mode, all the controls of the I/O View will be enabled and values can be read and updated in the view.

In addition to simply displaying the value of a register, the I/O View will display each bit in the register in a separate coloumn. Bits which is set will have a dark color by default, and cleared bits will have no color (default white). To change a bit, simply click it, and the value will be toggled.