Calculate checksum(hex) of string with ASCII(unsigned int). Use to detected communication error.

Dependencies:   StrLib

Revision:
0:b3a521e42246
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/StrLib.lib	Wed Oct 21 02:10:40 2015 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/AkinoriHashimoto/code/StrLib/#7bc89a64bfbd