mbed PWM output to play siren

Revision:
0:ed48c1d4c02f
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/.gitignore	Fri Oct 21 07:35:16 2016 +0000
@@ -0,0 +1,4 @@
+.build
+.mbed
+projectfiles
+*.py*