RE: [PARPORT] Realtime control of parallel port

Darren Bilby (
Tue, 28 Dec 1999 12:54:23 +1300

Can't remember exactly, but I believe the problems were in the ECP setup.

We wanted to keep firing things at the port indefinitely in ECP mode, but in
doing a write() it was, changing modes in and out of ECP (to PS2 mode?). The
parport code was excellent for firing out big blocks of data, but we were
sending it out 30 bytes at a time with a realtime app. It was doing a fair
bit of handshaking for every 30 bytes which it didn't need to do.

The extra handshaking confused our our hardware board which was only
minimally ECP compliant. In the end we were really asking a parport to do
things it was never designed to do, but with a bit of magik we made it go.

-----Original Message-----
From: Tim Waugh []
Sent: Tuesday, 28 December 1999 12:06 pm
To: Darren Bilby
Cc: Linux Parallel_Port
Subject: RE: [PARPORT] Realtime control of parallel port

On Tue, 28 Dec 1999, Darren Bilby wrote:

> Just been doing some of this myself. The parport code was excellent
> but had a pretty high overhead for our equipment and it was hard to
> debug when our hardware was doing bad things.

Where were you seeing most of the overhead, out of interest?


-- To unsubscribe, send mail to: --
-- with the single word "unsubscribe" in the body of the message. --

This archive was generated by hypermail 2.0b3 on Mon 27 Dec 1999 - 18:56:15 EST