© Radiometrix Ltd

Using a printer port to drive the RPC

Date: 22 - January 1998	Graham Sharples
Date: 27 May 1998 (updated)	Sabananthan Paramananthan

METHOD 1 , BI-DIRECTIONAL PORT (PS/2)

Port requirement - 8 bit bi-directional 
(PS/2 or ECP set to PS/2 Mode / Byte Mode)

  Connections -       RPC             25 WAY 'D' printer

RPC pins			PC (Printer Port) pins
Pin Labels	Pin		PS/2 Pins	Pin Label
GND	1		18 to 25	Ground
D0	2		2	Data 0
D1	3		3	Data 1
D2	4		4	Data 2
D3	5		5	Data 3
TXR	6		1	-Strobe
TXA	7		12	+Paper Out
RXR	8		13	+Printer Selected
RXA	9		14	-Auto Linefeed
RES	10		16	-Initialise Printer
5 Volt	11		+5 Volt Supply
GND	12		0 Volt Supply
+ve interupt			10	-Acknowledge

PC printer port registers
(addresses given for base address of 0378)

0378	data reg	b7	b6	b5	b4	b3	b2	b1	b0
		-	-	-	-	D3	D2	D1	D0

0379	status reg	b7	b6	b5	b4	b3	b2	b1	b0
		-	int	TXA	RXR	-	-	-	-

037A	control reg	b7	b6	b5	b4	b3	b2	b1	b0
		-	-	dir	Ien	-	RES	RXA	TXR

 

For Extended Capabilities Port (ECP) only

077A	Extended Control Register (ECR)	b7	b6	b5	b4	b3	b2	b1	b0
		0	0	1	-	-	-	-	-

Printer Port can be configured to operate in ECP mode by changing the Printer Port setting in BIOS from SPP or EPP to ECP. Press DEL key for AWARD BIOS or F1 for AMI BIOS when booting the computer. Then go to Integrated Peripherals section to change the settings for Parallel Port.
However, it may be necessary to change it back to SPP or EPP mode for some printers to operate properly.

int - +ve transition interupt bit, see "interupt drive"

Ien - bit is internal interupt enable, not used if polling used

1 = interupt enable , 0 = disabled (polled operation)

dir - bit is internal, controls direction of data output / input

0 = data pins are O/P's, ie drive data to RPC

1 = data pins are I/P's, ie read  data from RPC

note - RXA and TXR pins are inverted drives from the register

ie a 1 in the control register gives a 0 on the pin

all other registers / bits are true.

 

 

METHOD 2 , STANDARD PRINTER PORT (SPP)

Port requirement	Standard Printer Port (SPP)
	with Open Collector / Pull-up Control lines

Connections -       RPC             25 WAY 'D' printer

RPC pins			PC (Printer Port) pins
Pin Label	Pin		Pin	Pin Label
GND	1		18 to 25	Ground
D0	2		1	-Strobe
D1	3		14	-Auto Linefeed
D2	4		16	-Initialise Printer
D3	5		17	-Select Printer
TXR	6		2	Data 0
TXA	7		12	Paper Out
RXR	8		13	Printer Selected
RXA	9		3	Data 1
RES	10		4	Data 2
5 volt	11		+5 Volt supply
GND	12		0 Volt supply
+ve interupt			10	-Acknowledge

PC printer port registers
 (addresses given for base address of 0378)

0378	data reg	b7	b6	b5	b4	b3	b2	b1	b0
		-	-	-	-	-	RES	RXA	TXR

 

0379	status reg	b7	b6	b5	b4	b3	b2	b1	b0
		-	Int	TXA	RXR	-	-	-	-

 

037A	control reg	b7	b6	b5	b4	b3	b2	b1	b0
		-	-	dir	Ien	D3	D2	D1	D0

(B'00000100'= QUIECENT I/P)
( ie. 1111 on data lines  )

int - +ve transition interupt bit, see "interupt drive"

Ien - bit is internal interupt enable, not used if polling used

1 = interupt enable , 0 = disabled (polled operation)

note - D0, D1 and D3 pins are inverted drives from the register

ie a 1 in the control register gives a 0 on the pin

all other registers / bits are true.

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RPC Dev Kit comes with a DB25 Plug (Male Connector) for Standard Parallell Port with Open Collector / pull -up control lines. To use the RPC Dev Kit in PS/2 Mode, a special pair of interface cables are also provided.

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Internet sources of further information

Interfacing the IBM PC Parallel Printer Port.

Overview

This document is called an FAQ because it answers many commonly asked questions about the IBM parallel port, but it is formatted more as a brief tutorial. Read it twice before asking for more info; some stuff comes late.

• ftp://ftp.rmii.com/pub2/hisys/parport

• http://www.rmii.com/~hisys/parport.html

==== Version 0.96   9/1/94     Zhahai Stewart   zstewart@hisys.com

Here are some useful links for detailed information on Paraller Port Interface.

ftp://ftp.armory.com/pub/user/rstevew/LPT
Use of a PC Printer Port for Control and Data Acquisition
Kris Heidenstrom's PC Parallel Port Mini-FAQ   Release 10
Interfacing to the IBM-PC Parallel Printer Port
Interfacing the Parallel Port
Craig Peacock's Interfacing the PC.

If you have any technical enquires please contact our technical support team at tech_support@radiometrix.co.uk .