Article View: comp.std.c
Article #4710Re: PC Parallel port I/O
From: Jens Berg
Date: Fri, 26 Jan 1996 13:05
Date: Fri, 26 Jan 1996 13:05
25 lines
1755 bytes
1755 bytes
In <4e8344$975@unix13.u-3mrs.fr>, kris@esil.univ-mrs.fr (Christophe Cassar) writes: >Does anybody know how to receive more than 5 information on Parallel port. I assume that "5 information" means you want to read in more than 5 different signals from the parallel port. In fact, there is a possibility: You can read in 4 more signals over the connectors STROBE, AUTOFEED, RESET and SELECT_IN. Normally these pins are used as outputs. Fortunately these outputs are "open collector". If you program these port bits (via control port, that is ports base address + 2) to generate high output (5V) this level is provided via pull up resistors. If your external hardware generates enough output current to drive low level against these pull ups, you can read the information back via status port (ports base address + 1). Keep in mind, that STROBE, AUTOFEED and SELECT_IN are inverted: You program must, for instance, set ctrlport, bit 0 to 0 to get 5V at the physical pin STROBE. If the physical pin STROBE is at 5V level, you will read statusport, bit0 to be 0 (inverted again!). The RESET pin does not have this inversions, it is straight forward. Hope this helps ... [Jens] Jens Berg Hagenuk GmbH, Kiel - Germany Phone: +49 431 8818 70020, email: berg@hagenuk.de #include <standard.disclaimer> I only speak for myself!
Technical Details
Message-ID:
<4eajih$iu6@oskar.Hagenuk.de>Path:
arc1-ca.pugleaf.net!oskar.Hagenuk.de!newsReferences:
<4e8344$975@unix13.u-3mrs.fr>Show Full Headers
Complete Article Headers
Path: arc1-ca.pugleaf.net!oskar.Hagenuk.de!news From: berg@hagenuk.de (Jens Berg) Newsgroups: comp.std.c Subject: Re: PC Parallel port I/O Date: 26 Jan 1996 13:05:21 GMT Organization: Hagenuk Telecom GmbH Message-ID: <4eajih$iu6@oskar.Hagenuk.de> References: <4e8344$975@unix13.u-3mrs.fr> Reply-To: berg@hagenuk.de (Jens Berg) NNTP-Posting-Host: kst103_hat_jens_berg.hagenuk.de X-Newsreader: IBM NewsReader/2 v1.02