V.,

What is hooked up to the interrupt?

Normally, interrupt service routines are very lean and don't do any long term activity. The keyboard Scan() routine you call probably does many data transactions using i2c. This will take much longer than what is considered typical usage within an ISR. Not that it can't work, but usually you don't nest code that waits for other interrupts within one interrupt routine. And, that is what you seem to be doing.

By doing this, you also risk running out of stack space.


<>< Lance.