DragonFly On-Line Manual Pages

PPI(4)                DragonFly Kernel Interfaces Manual                PPI(4)

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

SYNOPSIS
     device ppi

     Minor numbering:  Unit numbers correspond directly to ppbus numbers.

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
     <dev/misc/ppi/ppi.h> <bus/ppbus/ppbconf.h>

     All I/O on the ppi interface is performed using ioctl() calls.  Each com-
     mand takes a single u_int8_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

     PPIGEPPA, PPISEPPA
             Get and set the address bits of the EPP control register.

     PPIGEPPD, PPISEPPD
             Get and set the data bits 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;
             u_int8_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 multi-
     ple operations together.

DragonFly 3.5                   January 2, 1998                  DragonFly 3.5