rashmi v / Mbed 2 deprecated SS_SensePOC2P0_12Dec2017_USERPID

created separate function for hex to char

Dependencies:   SDFileSystem ds3231 eeprom_Nikita mbed testUniGraphic_150217

Fork of SS_SensePOC2P0_11Dec2017_USERPID by rashmi v

An error occurred while processing your request

i2c_dec.cpp/shortlog@8316c23ec6b9: not found in manifest