pport - java direct parallel port access

Another way to the parallel port
You want to use your parallel port to control own hardware but don't want to play around with ioperms, registers, etc? Then here you are just right. The pport package offers you
  • Access to the port from java in user mode.
  • Access to the port via /dev/pport0 using standard file IO from scrips or applications (currently only for Linux).
  • Fast and precise timing for short periods through pport sequence mode - needed to time program pulses.

Warning: If you are not familiar with the parallel port hardware, don't try to apply voltage to the datapins and read the signal from pport0. You have to set the direction bit in the control register to set the datapins into hi-z mode to stop your parallel port card from driving the lines itself.
At the moment there is no windows support. I've started working on the code but someone with a windows compiler would be needed to get it working. Send a mail if interested, my estimation would be 3h of work to get it going.
The linux module works perfectly well on my machines, It seems that through intensive testing most of the bugs were removed (a bug would be rather nasty, since it occurs in the kernel in a region with interrupts disabled so debugging is difficult and most errors resulted in a complete kernel crash).
Before you start installing take a look at the pport documentation to check that pport is really what you are looking for.

To get started, download the pport binary version (pport_v1.2.zip) containing the .jar file needed and a precompiled linux kernel module (kernel version 2.4). If this doesn't suite your needs you may want to download the complete developer's version (pportdevel_v1.2.zip) containing the java source of the pport java library, the source of the linux module and source fragments for the windows native library. In both cases see pport.pdf for compile and installation instructions.
Both distributions contain the API documentation and a simple test tool to see if it works: Try java -cp pport.jar:. PortTest /dev/pport0 and click on the buttons to switch the parallel port lines on or off. You should immediately see a change in the voltage of the corresponding pin at the back of your PC.

Contact: e-mail me (%) halfdog.net
Last updated 16.7.2005