a sample program for 4th class

Dependencies:   beep_sound mbed

Revision:
0:b2827cba92a6
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/beep_sound.lib	Sat Sep 10 13:22:39 2016 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/RBH/code/beep_sound/#a64e653b0ce1