using LUT generate sine, square, triangle wave with variable freq

Dependencies:   mbed-dsp mbed

Revision:
0:4a2e0ba6c332
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-dsp.lib	Tue Nov 08 01:14:27 2016 +0000
@@ -0,0 +1,1 @@
+http://developer.mbed.org/users/mbed_official/code/mbed-dsp/#3762170b6d4d