I have a routine in my main program file for displaying float values on terminal program. When i try to use the same routine in my Interrupt service routine(ISR), it give an warning stating "Reference made to unresolved function". Secondly i also wanted to know how can i use a global variable in the ISR as its not possible to pass a parameter from any routine to the ISR.
Also study the volatile keyword. A global variable shared between an ISR and main code should be declared volatile.
"A global variable shared between an ISR and main code should be declared volatile." Note that this is in addition to Hans-Bernhard & Erik's notes about "atomic" accesses - not an alternative!