A long while back I devised a parallel type packet protocol that was used in the XTreeLink program to pass data between two PCs via their parallel ports. The ports were interconnected with a special cable wired for this purpose. This cable was a DB25 M-M cable commonly known in this industry as a LapLink cable or a DirectConnect cable.

The protocol and concepts used by this scheme could be very easily adapted to parallel communication between two microcontrollers as well.

Here is how the PC type cable is wired...


Here is a ZIP file of the basic code used for the transport level and the packet level of the communication scheme. It is in assembly language for those that are interested.

XTLink Parallel Driver/Packet Code


Michael Karas