Re: [PARPORT] ecp (8bit) nullmodem cable pinout?

Rafael Rodrigues Obelheiro (
Mon, 1 Feb 1999 08:48:20 -0200 (EDT)

On Sun, 31 Jan 1999, Andree Borrmann wrote:
> is there a standard for ecp 8bit nullmodem cables?
> How exactly are the status and control lines connected?
> If someone can answer these question I would volunteer to rewrite the plip
> driver to support 8bit modi.

I've been working on this stuff for a couple of weeks. I hope I'll be able
to deliver a working driver by the end of the month. So far, I've been
finding out several undocumented "features" of ECP (or, at least, of this
implementation of ECP), which is rather time-consuming. Right now, I have
a couple of programs that perform host-to-host communication in ECP mode,
but I'm still devising a suitable protocol (to control channel reversion)
so that a real PLIP-ECP driver can be written.

As for the wiring, I'm using

         D0-D7 ------/\/\/\------ D0-D7
       HostClk -----------------> PeriphClk
     PeriphClk <----------------- HostClk
       HostAck -----------------> PeriphAck
     PeriphAck <----------------- HostAck
ReverseRequest ---+-------------> X-Flag
    AckReverse <--|
        X-Flag <-------------+--- ReverseRequest
                             |--> AckReverse
   1284 Active -----------------> PeriphRequest
 PeriphRequest <----------------- 1284 Active

but this is still subject to change, since I've been experiencing some
tough problems.


Rafael Rodrigues Obelheiro
Rio Grande, RS, Brazil

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