I am printing a float value constantly ( 32.23) in lcd during that time if i give external interrupt signal constantly one time my controller restarts. Kindly tel me the reason
compiler ccs
dsPIC has flags in RCON register that can tell you about reset reason. Most likely you'll see a TRAPR (trap conflict reset), informing you that an unhandled trap was triggered before.
To see which trap it was (Stack Error Trap would be my first guess), you can implement trap interrupt handlers.
If this is all too much, consider a stack overflow as most likely reason. CCS PCD default stack settings have been too low for many years, particularly with float math. Increase the stack size.