SYNOPSIS

device ppi

Minor numbering: unit numbers correspond directly to ppbus numbers.

In dev/ppbus/ppi.h In dev/ppbus/ppbconf.h

DESCRIPTION

The driver provides a convenient means for user applications to manipulate the state of the parallel port, enabling easy low-speed I/O operations without the security problems inherent with the use of the /dev/io interface.

PROGRAMMING INTERFACE

All I/O on the interface is performed using Fn ioctl calls. Each command takes a single Ft uint8_t argument, transferring one byte of data. The following commands are available:

PPIGDATA , PPISDATA

Get and set the contents of the data register.

PPIGSTATUS , PPISSTATUS

Get and set the contents of the status register.

PPIGCTRL , PPISCTRL

Get and set the contents of the control register. The following defines correspond to bits in this register. Setting a bit in the control register drives the corresponding output low.

STROBE

AUTOFEED

nINIT

SELECTIN

PCD

PPIGEPP , PPISEPP

Get and set the contents of the EPP control register.

PPIGECR , PPISECR

Get and set the contents of the ECP control register.

PPIGFIFO , PPISFIFO

Read and write the ECP FIFO (8-bit operations only).

EXAMPLES

To present the value 0x5a to the data port, drive STROBE low and then high again, the following code fragment can be used:

        int             fd;
        uint8_t         val;
        val = 0x5a;
        ioctl(fd, PPISDATA, &val);
        ioctl(fd, PPIGCTRL, &val);
        val |= STROBE;
        ioctl(fd, PPISCTRL, &val);
        val &= ~STROBE;
        ioctl(fd, PPISCTRL, &val);