Mode 1—strobed output – National Instruments PC-DIO-24/PnP User Manual

Page 74

Appendix C

PC-DIO-24/PnP User Manual

C-14

/* EXAMPLE 1–port A input */

outp(cnfg,0xB0);

/* Port A is an input in mode 1. */

while (!(inp(portc) & 0x20));

/* Wait until IBFA is set,

indicating that data has been

loaded in port A. */

valread = inp(porta);

/* Read the data from port A. */

/* EXAMPLE 2–Port B input */

outp(cnfg,0x86);

/* Port B is an input in mode 1. */

while (!(inp(portc) & 0x02));

/* Wait until IBFB is set,

indicating that data has been

loaded in port B. */

valread = inp(portb);

}

Mode 1—Strobed Output

The control word written to the CNFG Register to configure port A for
output in mode 1 is shown as follows. Bits PC4 and PC5 of port C can
be used as extra input or output lines.

The control word written to the CNFG Register to configure port B for
output in mode 1 is shown as follows. Notice that port B does not have
extra input or output lines left from port C when ports A and B are both
enabled for handshaking.

During a mode 1 data write transfer, the status of the handshaking lines
and interrupt signals can be obtained by reading port C. Notice that the
bit definitions are different for a write and a read transfer.

1 = input
0 = output

Port C bits PC4 and PC5

1/0