Which device are you using (MSP430, CortexM3/M4, C2000, ...)?
If you are using MSP430, the definition of a timer interrupt is quite simple:
#pragma vector=TIMERA1_VECTOR
__interrupt void TimerA1_ISR (void)
{
// your code
}
You don't need to put a definition of the interrupt in an assembler startup file or similar. The compiler does this for you with the #pragma command (see above).
The list of available vectors can be seen in the device specific include file.
If this does not help, maybe you can post a code snippet explaining your problem?
