Table 4-4. Interrupt Enable Signals For All Mode Combinations - National Instruments PC-DIO-24 User Manual

Register-Level Programming

Table 4-4. Interrupt Enable Signals for All Mode Combinations

Port A Port A
Mode 2 Mode 2
Output Input
No No
No No
No No
No No
No No
No No
No No
No No
No No
No Yes
No Yes
No Yes
Yes No
Yes No
Yes No
The recommended jumper settings for W1 are as follows.
• PC6 — If port A is in mode 1 input.
• PC4 — If port A is in mode 1 output.
• PC2 — If port A is in mode 2 (port B is not in mode 1).
To enable interrupts from the PC-DIO-24, select PC2, PC4, or PC6 as the active low interrupt
enable signal. Initially, set the selected bit high to disable unwanted interrupts.
Program the PC-DIO-24 for the I/O mode desired. To enable interrupts from the 82C55A, set
either the INTEA or the INTEB bit to enable interrupts from port A or port B, respectively. In
mode 2, set either INTE1 or INTE2 for interrupts on input or output transfers. After interrupts
have been enabled from the 82C55A, clear the selected interrupt enable bit to enable interrupts
from the PC-DIO-24.
An external signal can be used to interrupt the PC-DIO-24 when port A or port B is in mode 0.
Select PC2, PC4, or PC6 as the interrupt enable bit and clear the selected bit to enable interrupts.
Connect the external signal that should trigger an interrupt to either PC3 or PC0. When the
external signal becomes logic high, an interrupt request occurs. To disable the external signal
interrupt, set the selected interrupt enable bit to logic high.
PC-DIO-24 User Manual
Port B Port B Port A
Mode 1 Mode 1 Mode 1
Output Input Output
No No
No No
No No
No Yes
No Yes
No Yes
Yes No
Yes No
Yes No
No No
No Yes
Yes No
No No
No Yes
Yes No
Port A Port B
Mode 1 Mode 0
Input
No No Yes
No Yes Yes
Yes No Yes
No No No
No Yes No
Yes No No
No No No
No Yes No
Yes No No
No No Yes
No No No
No No No
No No Yes
No No No
No No No
4-16 © National Instruments Corporation
Chapter 4
Port A Interrupt
Mode 0 Enable
Bit
Yes N/C
No PC6, PC2
No PC4, PC2
Yes PC6, PC4
No PC6
No PC4
Yes PC6, PC4
No PC6
No PC4
No PC2
No N/C
No N/C
No PC2
No N/C
No N/C