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       ieee1284_negotiate, ieee1284_terminate - IEEE 1284 negotiation


       #include <ieee1284.h>

       int ieee1284_negotiate(struct parport *port, int mode);

       void ieee1284_terminate(struct parport *port);


       These functions are for negotiating to and terminating from IEEE 1284
       data transfer modes. The default mode is called compatibility mode, or
       in other words normal printer protocol. It is a host-to-peripheral mode
       only. There are special modes that allow peripheral-to-host transfer as
       well, which may be negotiated to using ieee1284_negotiate. IEEE 1284
       negotiation is a process by which the host requests a transfer mode and
       the peripheral accepts or rejects it. An IEEE 1284-compliant device
       will require a successful negotiation to a particular mode before it is
       used for data transfer (but simpler devices may not if they only speak
       one transfer mode).

       To terminate the special mode and go back to compatilibity mode use

       These functions act on the parallel port associated with port, which
       must be claimed.

       With a device strictly complying to IEEE 1284 you will need to call
       ieee1284_terminate in between any two calls to ieee1284_negotiate for
       modes other than M1284_COMPAT.


   Uni-directional modes
       ·   M1284_COMPAT: Compatibility mode. Normal printer protocol. This is
           not a negotiated mode, but is the default mode in absence of
           negotiation.  ieee1284_negotiate(port, M1284_COMPAT) is equivalent
           to ieee1284_terminate(port). This host-to-peripheral mode is used
           for sending data to printers, and is historically the mode that has
           been used for that before IEEE 1284.
       ·   M1284_NIBBLE: Nibble mode. This peripheral-to-host mode uses the
           status lines to read data from the peripheral four bits at a time.
       ·   M1284_BYTE: Byte mode. This peripheral-to-host mode uses the data
           lines in reverse mode to read data from the peripheral a byte at a

   Bi-directional modes
       ·   M1284_ECP: ECP mode. On entry to ECP mode it is a
           host-to-peripheral (i.e. forward) mode, but it may be set to
           reverse mode using ieee1284_ecp_fwd_to_rev(3). It is common for PC
           hardware to provide assistance with this mode by the use of a FIFO
           which the host (or, in reverse mode, the peripheral) may fill, so
           that the hardware can do the handshaking itself.
       ·   M1284_EPP: EPP mode. In this bi-directional mode the direction of
           data transfer is signalled at each byte.

   Mode variations
       ·   M1284_FLAG_DEVICEID: Device ID retrieval. This flag may be combined
           with a nibble, byte, or ECP mode to notify the device that it
           should send its IEEE 1284 Device ID when asked for data.
       ·   M1284_BECP: Bounded ECP is a modification to ECP that makes it more
           robust at the point that the direction is changed. (Unfortunately
           it is not yet implemented in the Linux kernel driver.)
       ·   M1284_ECPRLE: ECP with run length encoding. In this mode,
           consecutive data bytes of the same value may be transferred in only
           a few cycles.


           The negotiation was successful.

           Negotiation is not available with this port type.

           Negotiation was rejected by the peripheral.

           Negotiation failed for some reason. Perhaps the device is not IEEE
           1284 compliant.

           A system error occured during negotiation.

           The port parameter is invalid (for instance, perhaps the port is
           not claimed).


       Tim Waugh <>


       Copyright © 2001-2003 Tim Waugh

                                  09/18/2007           IEEE1284_NEGOTIATION(3)