Saturday, May 9, 2015

PC Parallel Port Output Control

LED Control Using PC Parallel Port

The PC parallel port has 25 pins of which 8 pins can be used as outputs as well as inputs. To control these outputs we need a software to direct access this port. The LPT (parallel port) port speed is higher than the serial port speed and can receive many bits at a time. The following picture shows the parallel port pin assignment:

In this topic we are going to use just the data register (pins from 2 to 9).
I have build a software using Visual C# to fully control the outputs of the parallel port, this software runs only on windows 32 bit systems and .NET Version 4.0 or higher must be installed on the system otherwise the software will not run at all.
The following circuit schematic diagram shows an interfacing of parallel port with 8 LEDs: 

I named this application as "Parallel Port Output Control" and the main of this software is:

As we can see there are some buttons to control the eight leds, we can control each led individually or we can control these leds at the same time.
Note that you have to choose which parallel port you are using from the drop down box.
This application can be downloaded from the following link: