Re:add user interrupts on future device

Agree with rocksoft - timer usually is ideal - however with Cortex M3 SysTick (methinks) is even better. Its use frees the more complex timers - we simply count the desired number of "systicks" - and generate unique interrupts upon a "match."

It appears that you are weighing use of regular interrupts versus using some rtos. We may be able to better assist if you could further/deeper list your goals and objectives...