pport(1) - Linux man page

Name

pport - manipulate computer port pins

Synopsis

pport <flippers> [modifiers]pport <extensions>pport <information>

Description

The program pport is a simple yet handy program and its documented counterpart for accessing the output pins of multiple ports. Using this bundle, one can successfully control any household appliance or electronic device with minimal hassle and practically no changes. pport will alter the state (toggle or set) of the data pins specified by the user, of the parallel port or other supported ports using flippers to toggle or set, modifiers to alter the methods and provides information all availible from the contextual --help or -h options directly from the command line.

Conceived to change between the low or high state of the data pins of the parallel port, development extended its use to other common PC ports:

The i386 parallel port is a 25 pin D-shaped female connector in the back of the computer, conventionally used to connect a printer. Not all 25 pins are always needed. Thus it can alter the state of eight of those pins called data pins: 2, 3 4, 5, 6, 7 and 8. The rest are simple grounding pins as seen in the illustration below. Here is a scheme of the parallel port:

                               *-data pins D0 to D7
                      |D7 |D6 |D5 |D4 |D3 |D2 |D1 |D0    <---+
 _____________________|___|___|___|___|___|___|___|______    | count
*                     |   |   |   |   |   |   |   |       *  |
*    13  12  11  10   9   8   7   6   5   4   3   2  1    *  |
*                                                         *
 *     25  24  23  22  21  20  19  18  17  16  15  14    *
  *____|___|___|___|___|___|___|___|____|_______________*
       |   |   |   |   |   |   |   |    |
        +---+---+---+---+---+---+---+----+-----+
                         *                     |
                         |                     |
               groudning pins 17 to 25        ---
                                             ////

The data pins are D0 through D7. Pins 17 through 25 are the grounding pins.

The program also has support for the serial rs232 port. Although the IO is different from that of the parallel port, the serial connector rs232 can prove useful in many situations since it offers a serious amount of power (a voltage of +-12V or in some cases +-5V and short circuit current flow of 7-10mA) depending on the circuit types used in the PC circuitry. This is all at the cost of signal lines. The parallel port has eight data pins as we have seen above whereas the serial port has only three: TD(Transmit Data), DTS(Data Terminal Ready), RTS(Request to Send). However, only the last two are usable since TD is logic true(-12V) when no data is sent:

9 pin rs232           +-DTR       In order to avoid
      _______________|_______    confusion with the
     *                |       *  other parallel port
     *    1   2   3   4   5   *  we only mention that
      *     6   7   8   9    *   the 25-pin version of

       *________|___________*    the serial port has:
                |                    DTR = pin 20
                +_RTS_               RTS = pin 7

Based on the equivalence of both parallel port versions, pport accepts both standards transparently, either 9 pin or 25 pin serial rs232 connector.

Options

-p, --port <serial>: With this option one can select an alternative port.
-s, --set <pin1,pin2...|all|none|even|odd|random|dtr,rts>: Causes pport to set one, some, or all pins to high. Or to set all low with "none". dtr and rts are available only in combination with the serial port. One can also use all and none with the serial port option in order to set both RTS and DTR lines to high respectively low.
-t, --toggle <pin1,pin2...|all|even|odd|random>: Causes pport to toggle the state of the specified pins.
-w, --wait <Nd|Nh|Nm|Ns>: Where n is a number, causes pport to wait a specific time before altering the state of the specified pins, where n is a number, and d stands for days, h for hours, m for minutes and s for seconds.
-r, --restore: Causes pport to restore the previous state of the pins stored in the data file.
--status: Makes pport give a status report on the parallel port.
--debug: Will turn on debugging for the following command.
--raw: Will send raw data through the parallel port.

Examples

Here are a few examples for using this program:

pport -s all -w 10m: Will set all the pins to high after a 10 minutes delay.
pport -s random -w 5s: Will set some random pins to high after a 5 seconds delay.
pport -r: Will restore the previous pin states. This can be useful if you want to include pport in your startup scripts so it can restore your device status on system startup.
pport -t 2,4,7 -w 10s: Will toggle pins 2, 4 and 7 into their complementary state after 10 seconds.
pport -p serial -s rts: Will set the rts line of the rs232 port to the high state.
pport -p serial -s rts,dtr: Will set both lines of the rs232 port to the high state.
pport -p serial -s none: Will set both lines of the rs232 port to the low state.
pport --raw "Hello world": Will send data through the parallel port.

Notes

1. The pport utility, must be able to access the ports in the first place. Failure to do so will result in an error. Thus pport must have superuser priviledges at runtime.

History

This package is the uttermost practical embodiment of the Coffee-HOWTO originally written by Fotis Georgatos, <gef@hellug.gr> and Annie Pinder, < ajp@leguin.org.uk>. It tries to provide a standard for controlling computer ports quickly aiming at the same time to be simple. The "custom" howto provided, notably FRANKY-HOWTO, contains various hardware applications that can be used. It provides an updated set of ideas that could maybe realize the functionality you seek.

Authors

Written by Corcalciuc V. Horia (rain@sevenrains.ro)