In this section, you will modify the Blynk app, LED Controller, by configuring a virtual pin:

1. Go to edit mode by tapping the stop icon if you're already in play mode.
2. Tap the Button widget.
3. On the Button Settings page, tap GP 18 under OUTPUT. Scroll down and choose Virtual from the left-hand part of the list. Then, scroll down and choose V1 from the right-hand part of the list under PIN. Blynk provides 128 virtual pins for working with Raspberry Pi. Finally, tap OK.

4. Now, your Button Settings page should look like this:

5. Tap the LEFT arrow on the toolbar. You will see the new button configured with the virtual pin V1:

Now, you've successfully modified the Button widget, so it can write values to the virtual pin V1.