check program for USB Serial

Dependencies:   USBDevice

Revision:
1:637d33b55dfe
Parent:
0:941291e23892
diff -r 941291e23892 -r 637d33b55dfe mbed.bld
--- a/mbed.bld	Thu Aug 03 13:27:41 2017 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,1 +0,0 @@
-http://mbed.org/users/mbed_official/code/mbed/builds/a97add6d7e64
\ No newline at end of file