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
Let’s look at the diagram.
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.
Now another hour later the PCB looks like this and is working:
Now tonight, hopefully I’ll get some movement in the machine!