Well its complicated.
This integrated barcode application always working in the background with service. When I press hardware button on the left side of device, i turn on barcode scanner, and i can read barcode. Then this service in the background sends this result.
LogCat define this trigger key like KEYCODE_VOLUME_DOWN, but when I create function to detect key, no respond.
Sub Activity_KeyPress (key As Int) As Boolean
log(key)
End Sub