Hi! I've many interrupt service routines on my current project! But I didn't succeed in passing data between the main function and the ISRs! I declared global variables (no difference if static or not), but when the ISR is invoked, the value of the variables is 0xFF (unsigned char) oder 0xFFFF (unsigned int)! On the compiler the "small" memory model is selected! Any idea, what's wrong? Have a nice day! SVEN