Hi! I'm using timer 0 interrupt to sample data from an external ADC via McBSP1. The problem is that the interrupt routine only runs a limited number of times and then the program goes out of line. The CCS displays the error message: "Processor communication timeout". I'm also experiencing that variables in the .bss section are being overwritten by some unknown data. I've tried declarating the variables as volatile but it does'nt seem to work. I've declarated my ISR with or without the interrupt keyword but it didn't make no difference. I'm suspecting some kind of stack error but I can't figure out what's causing it. I'm a newbie on C programming for DSP's. I've been working a lot with assembler and MCU:s and some DSP before. I'm using TMS320VC5509 EVM CCS 2.1 and XDS5510PP plus. Please help! O_LaBero