Add variable in TinyOS symbol table

1. Add uint_8 volatile myVar=255; in Implementation.
2. In boot method, add myVar+=1;
3. Use this command to check if symbol is added: tos-set-symbols --read /build/telosb/main.exe
4. Change value of variable using:tos-set-symbols --objcopy msp430-objcopy --objdump msp430-objdump --target ihex build/telosb/main.ihex build/telosb/main.ihex MoudleName__myVar=30 TOS_NODE_ID=5 ActiveMessageAddressC__addr=5
5. Run your ihex file. 

Help resource: http://www.nourbakhsh.ir/blog/2012/01/symbol-table-manipulation-in-tinyos/