The project regards the construction of a simple breakout board, partially optoisolated, useful to protect the parallel port of the pc used to control the CNC machine and to simplify the wiring between the port and the controllers of the motor.
The schematic is quite elementary:
Only the input pins of the parallelport are opto-isolated. It is possible to power the board using the usb connector or using a 5V power supply.
This is the board pcb:
Schematics and brd files are available from the repository