Simple Printer Port Interface, Input-Output -
Printer Port Circuit to see the inputs logic state
and drive a few outputs. The preset control program
helps test out the circuit operation. Use safe 5V
This page triggered by "Use of a PC Printer
Port for Control and Data Acquisition" Printer
Page of Peter H.
So i made some example circuits and VB programs for
students. A demo Milli Volt source, Digital
Voltmeter and Logic Analyzer examples for learning,
are on these pages. I have tried to derive
power from PC itself in this circuit, Care should be
taken not to short circuit or apply any voltages
above 5V to PC Port Pins.
USB PIC a easy PC Interface
There are protection in all chips these days, but
you may stress the limits, so design and use opto
couplers to be on the safer side. See Parallel
printer port. that uses opto-isolators. and Opto-isolators.
74HCT373 is the only chip used to interface the real
world with the PC Parallel port. The Inputs to this
chip are protected with Resistors and Zeners. 3
outputs of PC are also monitored using LEDs. This
gives you a IO interface for experimenting. Below is
a Preset counter simulation that you can use with
this circuit for testing. Schmitt Triggers and
Signal Conditioning may be required for Noisy and
Port Interface, Input-Output - del20005
view circuit click the Link of PNG or PDF, The PNG
Image can be Drag Scrolled with Mouse.
The vb programs works well on xp-p4 and may not work
well on win98-P2 (speed). Logic inputs in above
circuit are floating add a 100K to ground for all 5
inputs if you want to use it as a logic probe.The
Logic Analyzer Program is here dla_demo.zip .
Demo Logic Analyzer 100KHz VB6 program with source
code, can be tried with this circuit. An Example to
get fast time in uS as vb timer min. 1ms is here perftmr.zip.
The design source is here 20005.zip.
A visual basic 6 program with source, to test this
circuit and experiment is here dpc_demo.zip.
Preset Counter Demo for Printer Port.
Parallel port to
drive a LED -read a switch
This page describes the use of a LED on a printer
port, to indicate something, for instance while the
PC screen is turned off or in screen save mode, like
whether your server is still running,
Humidity and Temperature on PC
Acquisition & Control
Do you have an old PC lying around the house which
absolutely no one wants? Then you can convert it
into a dedicated controller. Communicate with the
real world via the parallel printer port on your PC.
Simply connect printer cable from computer to D25
connector on relay board