Handle SDN pin with HW=4
Invert buzzer polarity for HW=4
Revert "Invert buzzer polarity for HW=4"

This reverts commit 10eac0103b0d6ccd2e13527abc6e51e5a38e0d62.
Merge pull request #1 from PTDreamer/master

Fix two minor issues with HW=4 define