Register-Level Programming Appendix E
Lab-PC+ User Manual E-34 © National Instruments Corporation
Single Bit Set/Reset Feature
Any of the 8 bits of Port C can be set or reset with one control word. This feature is used to
generate status and control for Port A and Port B when operating in Mode 1 or Mode 2.
Interrupt Programming for the Digital I/O Circuitry
Interrupts can be enabled on PC0, PC3, or both PC0 and PC3 by setting the DIOINTEN bit in
Command Register 3. See the Command Register 3 description earlier in this chapter for
corresponding bit positions.
An external signal can be used to generate an interrupt when Port A or B is in Mode 0. Program
PC0 or PC3 for input and connect the external signal that should trigger an interrupt to PC0 or
PC3. When the external signal becomes logic high, an interrupt request occurs. To negate the
interrupt request, the external signal must become logic low.