(EDIT: Revision 2 is available here)
Alright, after trying to bread board the interface between the parallel port and the various bits on the CNC machine I decided to put a board together real quick. I've used the well known method of toner transfer PCB etching.
- Pulls up on line 10 and 11 for home switches
- Break out all input and output lines
- The emergency stop line is on pin 1 and controls two relays controlling power to the machine.
- Power indicator LED
- Efficient switching power supply so hopefully we can use a small 12V 500mA wall wart to power the machine.
- Screw terminals
- DB25 connector
This diagram has one modification compared to what you'll see in my photos. I forgot to add the pull up resistors in the actual PCB, so I dead-bugged them on top. There really isn't much going on, pretty straight forward stuff.
The layout looks as follows with a mix of SMD and regular components.
This is what the resulting PCB before drilling the holes looks like. Yes it's not perfect but hey, it works and it definitely beats paying and waiting for a PCB.
Now another hour later the PCB looks like this and is working:
Now tonight, hopefully I'll get some movement in the machine!