Hi Friends,
we are interfacing MCP23017(4 nos.) with PIC16F1527.
Our target is scanning 64 keys with 4 port expander.
I have disable the intrrupts.
But when test push buttons continuously pressing on & off with 20 ms delay.
But after some time my MCU goes hanged.
Is anyone can suggest what i will try to overcome this problem.?
Thanks.

 

I suggest you post a schematic, and your code.
The most likely reason for a PIC (or any Harvard Architecture) machine to hang is waiting on a single condition that will never happen. In defensive programming you always need to test multiple conditions to exit from a loop.