NAME

       ppi — user-space interface to ppbus parallel 'geek' port

SYNOPSIS

       device ppi

       Minor numbering: unit numbers correspond directly to ppbus numbers.

       #include <dev/ppbus/ppi.h>
       #include <dev/ppbus/ppbconf.h>

DESCRIPTION

       The  ppi 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  ppi  interface  is performed using ioctl() calls.  Each command takes a single 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);

BUGS

       The inverse sense of signals is confusing.

       The ioctl() interface is slow, and there is no way (yet) to chain multiple operations together.

       The headers required for user applications are not installed as part of the standard system.

Debian                                           January 2, 1998                                          PPI(4)