Code:
grid var byte[5]
scan var byte

;timer 0 interrupt routine
BUTTONS:
GRID.0(SCAN) = 0
IF SCAN >= 39 THEN
SCAN = 0
ELSE
SCAN = SCAN + 1
ENDIF
GRID.0(SCAN)= 1
i managed to get this routine to scan the grids, and im able to display characters. however, the above piece of code prevents the program from going to the main program. so im forced to put the whole routine into the "buttons:" interrupt.

if i comment this exact piece of code, both main and interrupt routines run, but no scanning, ofcourse. i read up on the << shift command, and that can only go from 0 to 31. (i need 40)

is there any other way to increment the bits in a byte array?
thanks